Bot-S: Isaac Newton

Isaac Newton

A BIOGRAPHY

Louis Trenchard More

CHARLES SCRIBNER’S SONS

NEW YORK

1934

LONDON

Printed in the United States of America

All rights reserved. No part of this hook
may he reproduced in any form without
the permission of Charles Scribner's Sons

PREFACE

The bicentenary of Isaac Newton’s death (20 March, 1927) called
attention to the fact that we are without any satisfactory critical
biography of the man who is still regarded as the greatest of scientific
geniuses. His very greatness, his achievements in so many fields of
thought, and his studied aloofness from friends and society, have
combined to make the task of writing his life more than ordinarily
difficult.

Dr. Johnson twice expressed the opinion that only those who lived
with a man could write his life with any genuine exactness and dis¬
crimination; and then he added that biography is rarely well done
because few people who have lived with a man know what to select.
But it is doubtful if an exact and discriminating account of Newton’s
life and work could have been written by any one of those who knew
him personally. Even before his death he had been exalted into a
superman, a national monument to the glory of England, and such
an attitude of ecstatic adoration does not lend itself to dispassionate
judgement. At all events, none of his contemporaries is known to
have contemplated his biography except his nephew, John Conduitt;
he merely collected memorabilia from his friends and wrote a short
outline sketch. Judging from what he left, it was fortunate that he
abandoned the project and preserved his material for others to use.

While the fact, that Newton’s character and genius were regarded
almost down to the present day as not to be profaned by the breath of
criticism, greatly increases the perplexities of a biographer, the varied
and complex activity of his life is an even greater deterrent. It re¬
stricts to a very small number those whose knowledge is sufficiently
broad to undertake the work. In the first place, the biographer must
be thoroughly conversant with mathematics, physics, and chemistry,
and with the history and philosophy of those sciences during the
Renaissance. But Newton’s interest was by no means confined to
science; indeed if we accept his own statements he found it to be an
irksome taskmaster even during his period of greatest invention.
During the latter half of his life, his thoughts were absorbed in
theological and historical questions, and his activities in finance and

PREFACE

politics. An adequate life of Newton thus requires the biographer to
be equipped with a critical knowledge, in their broader aspects, of
both science and human affairs.

If the historian, trained in the humanities, is debarred by his lack of
knowledge of science, the difficulty is enhanced if we turn to the
scientist. It is rare enough for the scientific specialist of today to
have more than a rudimentary knowledge of the early history and
philosophy of his own field; and one would have to make diligent
search to find any who are capable of discussing the other subjects in
which Newton was interested. In spite of this lack of interest and
training, historical works on science, such as we have, are almost in¬
variably written by scientists. As a result, the biographies of those
scientists, whose lives were not absorbed in a narrow field of investi¬
gation, are lamentably lacking in philosophical and critical back¬
ground, and in human interest; they are belated and shadowy sur¬
vivals of the mediaeval monkish chronicles.

Lastly, in this day of the utilitarian omnipotence of science, it is
extraordinarily difficult for a biographer to sympathise with, or even
to appreciate, the conviction of Newton and his contemporaries that
their purpose in the cultivation of science was to demonstrate the
action of the divine will in the natural world, and not to contribute
to our comfort, safety, and power.

Whatever may have been the true cause of the neglect, we have
only one biography of Newton which can, in any sense, be deemed
worthy of its subject. In 1855, Sir David Brewster, a physicist dis¬
tinguished chiefly for his investigations in optics, published The
Memoirs of Sir Isaac Newton . We owe to him a debt of gratitude
for his diligence in collecting materials; but in spite of many ad¬
mirable qualities his work, by and large, is inadequate and untrust¬
worthy.

Brewster adopted throughout his book the role of advocate to “The
High Priest of Science” as he calls Newton. His hero is to be por¬
trayed without blemish intellectually and morally, and it is his duty
to explain away whatever may mar the ideal he would create. He
says of himself that, where he found evidence which confirmed facts
known to reflect adversely on Newton’s character, he published it;
but if the facts were not previously known, he felt bound in honour
to respect the privacy of his discovery. The irritation and suspicion
which such a policy inevitably arouses in the mind of the reader de-

PREFACE

Vll

feated his purpose. In contrast to the blameless character traditional¬
ly ascribed to Newton, there have been persistent rumours about his
religious heterodoxy, and about certain weaknesses of temperament,
which would have been quieted if all the facts of his life had been
freely given. There is absolutely nothing in his life so serious that it
should have been suppressed.

There is in Brewsters Memoirs almost no attempt to present
Newton as a living man or to give a critical analysis of his character.
And, if we can judge from his treatment, the author was not com¬
petent to discuss the science or the philosophy of the seventeenth and
eighteenth centuries. It is also unfortunate that the importance of
Newton’s political and religious work is neglected, since it is easy
to prove that he played an important role in the Revolution of 1687,
and John Locke considered him to be one of the most profound
theologians of his day. As this biography is the only one which even
pretends to be authoritative, there is no need of apology for offering
a new life of Newton.

A reference should be made to the principal sources of material for
the present biography. With the efficient aid of Messrs. Henry Soth-
eran and Co., a practically complete collection of published works
relative to my subject was obtained and also a number of rare
pamphlets and private notes of Newtonian scholars. References to
these works are carefully noted in the text. Wherever possible I also
secured copies of each of the editions of important works and, in sev¬
eral instances, this practice proved to be important in settling vexed
questions.

In only a few cases, I failed to find copies of needed works and
these deficiencies were supplied by photostatic reprints. I wish to ex¬
press my sincere thanks to the Director of the British Museum for the
copy of a variation in the text of one of the two editions of Raphson’s
History of Fluxions which I could not find; to Dr. Brasch of the
Library of Congress for a copy of those parts of Mrs. de la Riviere
Manley’s Eginardus which refer to the Earl of Halifax and to Mrs.
Catherine Barton; to the Directors of the Pierpont Morgan Library
for a copy of Newton’s Memorandum Boo\ which is one of the
treasures of that collection.

While there are a few unpublished Newtonian documents in vari¬
ous places, the one great and indispensable collection is that belong¬
ing to the Portsmouth family. All of Newton’s papers, manuscripts,

PREFACE

• • •
vm

and documents, at his death, passed into the possession of his niece
Catherine Barton, the wife of John Conduitt. Her only child, Cath¬
erine Conduitt, married John Wallop, Viscount Lymington, and
their son was the second Earl of Portsmouth. These papers, which
have remained in the possession of that family ever since, are known
as the Portsmouth Collection.

Shortly after Newton’s death, Conduitt’s manuscripts and memo¬
randa were added to the Portsmouth Collection and they are the
principal source of material for his personal life and character.

It is quite evident that a satisfactory biography of Newton cannot
be written unless the author has the privilege of using freely the
Portsmouth Collection. By the interest and courtesy of The Master
of Trinity College, to whom I am under other obligations for many
instructive and happy days when in Cambridge, I was permitted to
inspect and use all the Newton manuscripts in the University. I am
even more grateful to Blanche, Lady Portsmouth, and to her
nephew, Viscount Lymington, who, although I was then a stranger
to them, sent their priceless collection in Hurstbourne Park to the
British Museum in order that I might examine and use it at my
leisure. I have also to thank them for allowing me to have reproduc¬
tions made of portraits of Newton at Hurstbourne Park. It is a
pleasure also to express my thanks to the Custodian of Manuscripts
of the Museum who gave me every convenience and help during
those weeks of work, in which I read and copied the manuscripts
written in the beautifully clear handwriting of Newton.

So far as I can learn, the Portsmouth Collection has been examined
for use by the following persons i 1

1. Dr. Thomas Pellett, F. R. S., was appointed by Newton’s execu¬
tor in 1727 to examine and select such manuscripts as he thought to
be fit for publication. A rough catalogue of the papers was appended
to the bond given by Conduitt and was published in Hutton’s Math¬
ematical Dictionary. As a result of this examination, the Abstract of
the Chronology and the Chronology of Ancient Kingdoms Amended
were issued in one volume by Conduitt in 1728.

2. The whole collection was inspected by Bishop Horsley, F. R. S.,
while preparing his Opera Omnia Newtoni, 1779-1785, in five quarto
volumes. He made a few unimportant notes on some of the papers
but he made no use of them. It was rumoured that he opposed the

1 Much of this information is taken from the Catalogue of the Portsmouth Collection.
Cambridge University Press, 1888 .

PREFACE

publication of Newton’s theological writings because of their het¬
erodoxy.

3. In 1806, Edmond Turnor, whose family had purchased and still
own Newton’s Manor, inserted in his book on the Town and So\e of
Grantham some of the material collected by Conduitt.

4. Brewster, while preparing for his Memoirs of Newton, 1855,
was given the rare privilege of inspecting the collection at his leisure.
He made a very considerable use of Conduitt’s manuscripts and of
abstracts from Newton’s correspondence, and some use of the math¬
ematical notes and papers. He, however, used his discretion in ex¬
tracting and in omitting many important documents which seemed
to him not advantageous to Newton’s reputation.

5. About 1872, the Earl of Portsmouth, after a fire at Hurstbourne,
decided to present to the University of Cambridge all that portion of
the papers which related to science with the provision that those con¬
cerning Theology, Chronology, History, and Alchemy should be re¬
turned to Hurstbourne Park, where they would be carefully pre¬
served.

The papers of personal, private, and family interest were also re¬
turned to Lord Portsmouth, but copies of the more important letters
were made and deposited in the University Library. During his last
illness, Newton burned a great mass of personal papers; and he must
have wished to preserve the same jealous aloofness after death which
he had maintained during life for no family nor intimate letters were
saved. 2 There is little probability that any important collection of his
letters to his relatives will be discovered; if such had existed, Conduitt
surely would have sought for them when he was collecting materials
for his biography. Nor can we hope that any unknown significant
collection of his correspondence with acquaintances and friends has
been preserved. Newton was singularly averse to writing letters, and
he rarely mentioned any personal matters in the few he wrote. We
might almost accuse his contemporaries of having entered into a
conspiracy to destroy all the evidences of his humanity in order that
he should be thought of as a pure ideal of intellectual genius.

When the Portsmouth Collection was received by the University, a
syndicate was appointed consisting of H. R. Luard, G. G. Stokes,

2 In the Preface of the Catalogue of the Portsmouth Collection, a short note of Newton’s
mother written to him at College is mentioned. I could not find it although I made special
search for it. I did, however, find a note to Sir John Newton, in Soho Square, from his
mother.

PREFACE

}. C. Adams, and G. D. Liveing, of which the Astronomer Adams
was the most active member. The papers were found to be in great
confusion and a large portion had been grievously damaged by fire
and damp. The syndicate carried through their work in a most
thorough manner. The papers were sorted and classified in sections
with a short descriptive note for each item. This very laborious and
excellent work of the syndicate was finally published, in 1888, by the
Cambridge University Press with the title, A Catalogue of the Ports¬
mouth Collection.

The letters and other quotations used in this Life were transcribed
by me from the originals or from printed copies. One or two of
Newton’s shorter letters have been printed literally in order that
exact specimens of his orthography may be exhibited. Modern Eng¬
lish usage has been adopted in the other quotations, since it would
merely annoy the reader and serve no good purpose to have retained
the original spelling and abbreviations. While I am personally re¬
sponsible for the translation into English of all the documents quoted,
I did in a few cases submit my rendition for approval to classical
scholars more proficient than myself. Without trying to adapt my
style to that of the eighteenth century, it was found to be advisable to
limit my vocabulary as far as possible to words which were then in
ordinary usage, so that there would be a less abrupt break in style
between quotations and the rest of the text. T T M

Graduate School,
University of Cincinnati,
January, 1934.

CONTENTS

CHAPTER PAGB

I. Early years. 1642-1661 I

II. Cambridge University. Student life. Early discoveries.

1661-1669 21

III. Lucasian professor. Lectures on optics. Invention of

REFLECTING TELESCOPE. HlS NEW THEORY OF LIGHT. 1669-

1673

IV. Argument on the nature of light. Newton on theory

AND HYPOTHESIS 82

V. Trinity College. Character of Newton. Correspond¬
ence with Collins and Oldenburg on light and mathe¬
matics. 1669-1674 122

VI. Alchemy and chemistry. His personal life. Relations
with Hooke. Early mathematical work. Invention

OF CALCULUS. CORRESPONDENCE WITH LEIBNIZ. 1674-

1676 157

VII. Life in Cambridge. On the nature of the aether.

Friendship with Montague. Early work on gravita¬
tion. 1676-1685 199

VIII. The mechanistic hypothesis from Democritus to Newton 253

IX. The “Principia.” 1685-1687 286

X. The Alban affair and the revolution. Correspondence
with John Locke. The Boyle lectures. Serious ill¬
ness. 1687-1693 335

XL Reluctance to publish. The lunar theory and corre¬
spondence with Flamsteed. Appointment to the mint.
1693-1696 393

XII. Revision of the coinage. Life in London. 1696-1703 438

XIII. Presidency of the Royal Society. Publication of “His-

TORIA CoELESTIS. ’ ’ KnIGHTED AND STANDS FOR PARLIA¬
MENT. Second edition of the “Principia.” 1703-1709 494

CONTENTS

CHAPTER

XIV.

XV.

XVI.

XVII.

Controversy with Flamsteed. Second edition of “Prin-
CIPIA. 1709-1713

Controversy with Leibniz on invention of the calculus.
1699-1718

Ancient chronology. Theology. Religious beliefs

The LAST YEARS. 1718-1727

Index

PAGE

539

565

608

648

669

ISAAC NEWTON

CHAPTER I

EARLY YEARS
1642-1661

S ituated some seven miles south of Grantham, in Lincolnshire,
is the little hamlet of Woolsthorpe. It comprised, in the
seventeenth century, a modest manor-house, two or three small
farms, and a few thatched cottages; the nearest church to the ham¬
let was in the village of Colsterworth, about a half mile to the east.
The settlement lies in the beautiful valley of the Witham, and it
would have remained in peaceful obscurity if it had not chanced to
be the birth-place of Isaac Newton.

Grantham, in the period of the Stuarts, was a town of three or four
hundred families, and had been sufficiently important to have been
the seat of a suffragan bishop; and two noblemen, at least, had taken
their titles from it. This whole region was the seat of the wars of the
Commonwealth; Charles I raised his standard at Nottingham, thirty
miles to the west, and the battles of Marston Moor and of Naseby
were fought in these eastern counties. Cromwell recruited most of his
famous Ironsides from the yeomen of Huntingdonshire, and estab¬
lished his headquarters in Cambridge. Grantham lay in a direct line
between these two regions, and its inhabitants must have suffered
continually from foraging parties and from the general disorder of
civil war.

In this environment, in the Manor House of Woolsthorpe-by-
Colsterworth, Isaac Newton was born on Christmas Day, 1642, and
in the same year that Galileo died. A week later, he was carried to
Colsterworth, and the visitor may still read in the parish record:
“Isaac sonne of Isaac and Hanna Newton Baptized Jan. 1, 1642/3.”

The Manor House is a moderate sized building of gray stone, fac¬
ing west and near the orchard which contains a scion of the apple
tree famous as the inspiration for the discovery of the law of gravita¬
tion. Above the front door, which is narrow and low, is a tablet
commemorating the birth of Newton. On the first floor, the rooms
are fairly large with low ceilings and stone floors. A steep and nar-

ISAAC NEWTON

row stair-case leads to the bed-rooms in the second story. The room in
which Newton was born is on the left; a drawing of the apple tree
hangs on the wall, and over the fire-place is a stone tablet inscribed
with Pope’s couplet:

“Nature and Nature’s Laws lay hid in night;

God said, Let Newton be!—And all was light.”

The room, to the right, was probably his bed-room; and a space parti¬
tioned off in the southeast corner was used as his study. Several
windows were blocked in order to reduce the window tax, and some
of them have since been reopened.

The manor of Woolsthorpe 1 is first mentioned in 1450 as belonging
to a gentleman named Pigot. It passed into the possession of several
families till it was purchased, in 1614, by Robert Underwood, who
demised it nine years later to Robert Newton, the grandfather of
Isaac Newton. While the manor was a small and poor estate, rated
£> 3 ° a year, its owners were true lords of the manor, with court
leet and court baron, and perhaps pit and gallows. Isaac possessed
these rights all his life, after attaining to his majority.

Of Newton’s ancestry, it has been impossible to go back with cer¬
tainty further than his grandfather, Robert. In 1705, after Isaac
Newton had been knighted and was at the height of his fame, he
was granted, on the strength of his personal affidavit made to the
College of Arms, a pedigree dating back to John Newton of Westby,
in Lincolnshire. 2 The affidavit was accompanied by a certificate from
Sir John Newton of Thorpe, who, as head of the family, stated his
father had said that Isaac Newton was his relation and kinsman;
that John Newton of Westby was their common ancestor; and that
he believed the said Sir Isaac Newton to be descended from the
oldest son of the said John Newton: “but knoweth not in what par¬
ticular manner, but that the said Sir Isaac hath always been reckoned
by him of the said name and blood with his family.” The arms of

1 Much of our information about Newton’s life and home was collected by Edmund Turnor,
Esq., of Stoke Rochford, and published in his Collections for the History of the Town and
So\e of Grantham, London, 1806. In 1732, the manor and estate of Woolsthorpe passed to
the Tumors by purchase from John Newton, heir-at-law of Sir Isaac, and is still in their pos¬
session. The manor has been restored, and generous permission is given to visitors to inspect
it. Edmund Turnor was an antiquary, much interested in local history; he also had access
to the Portsmouth Collection. He was thus the first to make public many of the facts and
stories of Newton’s life.

~ Turnor (p. 158) found this bit of corroboratory evidence: “The oldest property of the
Newtons at Woolsthorpe was a messuage and lands purchased by John Newton of Westby in
1561.”

EARLY YEARS

Newton a Sable, two shin bones saltire-wise, the sinister sur¬
mounted of the dexter, argent.” And above the entrance of the
manor of Woolsthorpe some one had carved two shin bones, the
emblem of his family. There is undoubtedly a serious break in this
pedigree and we cannot be at all certain that it is authentic. The
Newtons of Thorpe were, probably, only too proud to claim an
Isaac Newton for their family and he himself, during his official life
in London, apparently valued kinship with a county family of gentle
birth. This concern over his pedigree at any rate shows his desire to
be thought of as a gentleman. But the actual facts are that the New¬
tons of Woolsthorpe were yeoman farmers, that the oldest property of
the family was a messuage and lands purchased by John Newton of
Westby in 1561, and that Isaac Newton could not with certainty

trace his ancestry further than to his grandfather. 3 4

Of Newton’s immediate family, we know very little except that his
grandfather, Robert, was buried in Colsterworth churchyard, Sep¬
tember 20, 1641* Robert’s oldest son, Isaac, was proprietor of the
manor for only a year and a month when he died at the age of thirty-
seven and was buried in Colsterworth on October 6, 1642. He had
been married only a few months and so never saw his illustrious son.

If we look for traits of character in Newton’s family which might
predict his genius, we certainly cannot find them in his paternal
ancestry. The Newtons were not distinguished by any unusual ability
and the only reference we have of his father is that he was a wild,
extravagant, and weak man.” 5

Turning to Newton’s maternal side, we have evidence that his

3 Stukeley ( Portsmouth Collection) states that the Parish Registers were miserably kept.
Although there were found numerous Newtons in the Parish yet, because of the defective
Register, a correct genealogy could not be drawn up. Stukeley thought that Newton did not
have his genealogy drawn up, but in this he was mistaken; while Newton lived in Germyn

Street he had one prepared by the College of Heralds. .

4 The pedigree which is given in this volume was preserved in the Portsmouth Collection
and copied by me. Dr. William Stukeley (1687-1765), who first copied it and sent it to Dr.
Meade, physician to Newton, was an antiquary, and practised as a physician in Boston, Lon¬
don, and Grantham; after 1729 he was successively vicar in Stamford, Somerby, and Queen s
Square, London. He was an intimate acquaintance of Newton’s and at the time of Newton’s
death, he was living in Grantham. On the request of Conduitt, Newton’s nephew-in-law,
who was preparing to write a life of his uncle, Stukeley collected all the information e
could find in Grantham and Colsterworth and sent it in a letter, with his personal reminis¬
cences, addressed to Dr. Meade. Although Conduitt never wrote the intended life, his MSS.
and notes which he collected from Stukeley are preserved in the Portsmouth Collection and
are the principal source of our knowledge of Newton s personal life, I have checked all these
MSS. and have now given much that has never before been published.

5 This information was published by Maude in his Wensleydalc. It was given to him by
his neighbour, the Rev. Barnabas Smith, stepfather of Newton. Cf. de Villamil, Newton: the
Man, London, 1932, p. 29.

ISAAC NEWTON

mother was a woman of high character and fine intellect. She
greatly favoured her son Isaac, and their relationship was extraor¬
dinarily affectionate and tender. Conduitt 6 left this charming sketch
of her character: “His mother was Hannah, the daughter of James
Ayscough of Market Overton in the county of Rutland, a family
formerly of great consideration in those parts—one of them built
great Paunton Steeple, a curious fabric between Grantham and
Colsterworth—Her mother of the Bliths of Stranson in Lincoln¬
shire, now extinct... then on both sides of a fair and honourable ex¬
traction, but what was of much more consequence to her son, she was
a woman of so extraordinary an understanding, virtue, and goodness,
that those who think that a soul like Sir Isaac Newton’s could be
formed by anything less than the immediate operation of a Divine
Creator might be apt to ascribe it to her. . .. She remained a widow
several years, and employed her time educating her son and doing
good works.” However, she transmitted to her three children by her
second marriage no traits of distinction; and of the next generation,
with the exception of Catherine Barton, four at least were anything
but a credit. Those who are eager to trace the seeds of genius by
heredity can find but little satisfaction, for Isaac Newton appeared
in a family in no wise distinguished by any other event.

Newton not only had no apparent advantages of racial stock, but
he also had a most unpromising start in life; he was not only a
posthumous child, but he was also prematurely born and so frail that
two women who were sent to a Lady Packenham at the nearby vil¬
lage of North Witham to procure something for him, did not expect
to find him alive on their return. And for some time he wore a
bolster round his neck to support his head as he was too weak to hold
it upright. In his later years, he was fond of repeating that his mother
often told him that he might have been put into a quart mug. But
in spite of his untoward birth, he must quickly have acquired vigour.
This may be inferred from the fact that his mother married again
within two years and went to live with her husband, the Rev. Barna-

John Conduitt married Catherine Barton, Newton’s niece, in 1717, and lived with his
uncle for the last ten years of his life. He wrote a letter (published by Turnor) to Fontenelle
to correct mistakes made in his Eloge for the French Academy, and collected much informa-
fnends for an intended life of Newton, for which only a sketch was written. All
of his MSS. are preserved in the Portsmouth Collection, excepting one which was unfortu¬
nately destroyed in a fire at Hurstbourne.

Conduitt was educated at Westminster School and Trinity College, Cambridge. He trav¬
elled much in Portugal on public business; was a Member of Parliament, and Newton’s suc¬
cessor at the Mint. His only daughter married John Wallop, Viscount Lymington; and their
son became the second Earl of Portsmouth.

PEDIGREE OF S' I. N. COPIED FROM HIS OWN HANDWRITING AT COLSTERWORTH 15 JUNE, 1727

N. B. What is italicised is of ray [Stukeley’s] addition
John Newton of Westby in Lincolnshire descended from Newton of Lancashire

EARLY YEARS

ISAAC NEWTON

bas Smith, at North Witham, a village about a mile south of Wools-
thorpe. For some reason, she considered it better to leave Isaac at
Woolsthorpe in the care of his grandmother Ayscough and under
the guardianship of his uncle, James Ayscough.

We can impute her marriage to prudence as Mr. Smith was a
bachelor, fifty years of age, and had an independent income of
in addition to his salary as Rector. It seems that he was advised by
one of his parishioners to marry, but he objected on the ground that
he did not know where to meet a good wife. The widow Newton
was recommended; but he again objected that he would not wish to
ask her and be rejected. It was finally agreed that the parishioner
should do the proposing and receive a fee for his day’s work. Her
answer was that she would be advised by her brother Ayscough,
and so the same man went to Mr. Ayscough on the same errand.
When the brother approved, the marriage was arranged. But the
widow Newton stipulated that her son Isaac should have not only
the income from Woolsthorpe, but that Mr. Smith should give him a
parcel of land lying in Sewstern worth ^50 a year and also repair
and enlarge the Manor House.

Newton received his first education at two little day-schools in
Skillington and Stoke which were near enough to his home to per¬
mit him to walk thither and back by himself. He stayed at these
schools till the age of twelve, learning the reading, writing, and
arithmetic of the time. Having outgrown their usefulness he was
sent to the King’s School in Grantham. He stayed there only four
years as his mother then brought him home from school to learn to
be a farmer and to manage his estate. The immediate reason for this
change in his life was due to the death of his stepfather, which oc¬
curred in 1656. His mother returned to Woolsthorpe, bringing with
her the three children,—Benjamin, Mary, and Hannah Smith,—of
her second marriage. The circumstances of the family had been
much improved, as she had her husband’s estate, worth some ^500
a year, and he had also rebuilt and enlarged the Manor House.
However, the burden of maintaining a family, now large, and of
managing a farm were doubly hard at this time because of the Civil
Wars. In this emergency she turned to her son for assistance. The
boy, now sixteen years old, had evidently not impressed his family as
having any ability out of the ordinary; it was natural, then, to expect
him to succeed his father, and for a yeoman farmer a rudimentary
education was thought sufficient.

EARLY YEARS

The plan was a complete failure, although it was persisted in for
more than a year. The failure was due neither to willfulness nor to
waywardness on the part of the boy, as he was docile and gentle by
nature, but to a total lack of interest in the work of the farm. His
years at school in Grantham had developed him from a child to a
youth, and his intellectual tastes had begun to show themselves.
Although he had become fond of books, his absorbing interest lay in
the design and construction of mechanical toys and models. His re¬
turn to the farm was utterly distasteful to him, and he could not be
induced to show any interest in its management. If set to watch the
cattle or sheep, he would pass the time reading, or making models of
what struck his fancy with his knife; and while he was thus en¬
grossed in his fancies, the animals strayed at their pleasure. The fol¬
lowing anecdote may not tell the whole story, but it does bring to
one a mental picture of a lonely and misplaced boy beginning to
feel the powers of his genius. It recalls the story told of the youthful
Giotto who passed the long and monotonous hours in the fields ab¬
sorbed in the delight of drawing likenesses of his sheep, rather than
in herding them.

A principal part of his duties consisted in going to market at
Grantham on Saturday under the care of a trusted old servant in
order to learn the intricacies of barter and trade. But they no sooner
reached the town, and had put up their horses at the Saracen’s Head
Inn in Westgate, than he left the business to the servant and went to
a Mr. Clark’s house where he had formerly lodged. He stole into the
garret and immersed himself in the delight of reading a parcel of
old books which had been stored there; or he would ensconce himself
under a favourite hedge at the foot of Spittlegate Hill, just before
one enters Grantham, and pass the day reading and studying until
the servant picked him up on the way home. He also fitted up for
himself a study room, and here he made shelves to hold his few
books, his mechanical toys, and his other boyish treasures; the walls
he decorated with pictures, many of them drawn by himself and
mounted in frames of his own handicraft. His mother finally gave
up the experiment when she found that he was quite unfit to be a
farmer, and agreed to send him back to school at Grantham to be
tutored for college.

It would be difficult to estimate what the world owes to this de¬
cision of Newton’s mother to send him to the University, nor did she
imagine the honour which was in store for her and for him. And

ISAAC NEWTON

we can place the decision to the perspicacity of Mr. Stokes, the
Master of Grantham School, for it seems, according to Stukeley, 7
that: “In the meantime Mr. Stokes, who had a great value for him,
often strongly solicited his mother to return him to his learning, the
proper channel of his inclinations. He told her it was a great loss to
the world as well as a vain attempt to bury so promising a genius in
rustic employment, which was notoriously opposite to his temper;
that the only way whereby he could either preserve or raise his
fortune must be by fitting him for the University. That if she sent
him to school again he would remit his salary, which is forty shil¬
lings a year for those boys not born in the town or a mile distant
which would alleviate the charge. In short, he prevailed upon her,
and he remained at school till he went to the University. Thus in the
main, the world is indebted to Mr. Stokes for the incredible advance
in philosophy which this age has reaped from the studies of Sir
Isaac Newton.” This advice was supported by his uncle, the Rev.
William Ayscough, rector of Burton Coggles. It is related that he
found the boy under a hedge busied with a mathematical problem,
when he should have been engaged in other business, and recom¬
mended that he be sent to Trinity College, Cambridge, where he,
himself, had been educated.

There has been a considerable variation in the statements of the
length of time Newton attended school. After a careful comparison
of all the facts obtainable I feel sure that the following calendar is
the most probable. After leaving the day schools at the age of twelve,
he spent four school years at Grantham, beginning in the autumn of
1654; he then passed two years and a summer at home and returned
to Grantham in the autumn of 1660; he was admitted as Subsizar at
Trinity College, June 5, 1661. If these dates are accepted, his formal
education at Grantham lasted in all five school years. 8 It is important
to establish the dates of those critical years. His preparation at
Grantham would be sufficient for entrance to college, for boys went
up to Cambridge younger in those days than now and the standard
of admission was especially low because of the demoralisation of the
times. But, while he may have shown ability at school, his aloofness

7 Cf. Portsmouth Collection.

8 For example; Edleston, in his Synoptical View of Newton's Life, prefixed to his edition
of Newton’s Correspondence with Cotes (London, 1850), gives the following table:

“1655, Sent to Grantham School.—1656, Taken away from School.—1660, Sent back
to school to prepare for college.—1661, June 5, Admitted Subsizar at Trin. Coll.; July 8,
Matriculated Sizar.” Thus Edleston gives four years and three months to his life on the farm,
and only two school years at Grantham. His errors are due to the fact that he did not have

EARLY YEARS

and the independent power of his imagination are what most im¬
press us. Nor is this supposition unwarranted, as it was character¬
istic of him to accomplish his best work so secretly, and so unexpect¬
edly, that no one knew when, or how, it had been prepared.

We can make a fairly certain conjecture as to the studies in which
Newton would be tutored. The groundwork of his preparation was
undoubtedly in the classics as it was for all University matriculates.
Latin especially was important, as it was used generally as the
medium for scholarly books, for correspondence, and in conversation.
He would need to know less Greek, but it was a necessary and im¬
portant subject. Modern languages were not required, and he
learned little French and no German. Hebrew in fact was con¬
sidered more important, and one of his memorandum books of this
period shows that he had an acquaintance with the Hebrew char¬
acters. He would be thoroughly drilled in ancient or classical history,
which was thought to be a much more important subject than con¬
temporaneous history; and it was also a subject which he cultivated
all his life. He would have lessons in Christian exegesis, Biblical his¬
tory, and in grammar,—the latter sufficiently to study Sanderson’s
Logic as one of the first books to be read at college. In mathematics,
his preparation was slight and must have been limited to arithmetic
and a little geometry. The problems which are said to have engrossed
his boyish years were probably merely simple calculations incident
to his mechanical contrivances. It is at least certain that he had not
studied Euclid with any thoroughness till he went to Cambridge.
The above studies seem fairly certain; what else he may have learned
must be left to conjecture.

Almost all our knowledge of Newton’s early years is derived from
the recollections of those who knew him while at school at Gran¬
tham. As the incidents are not dated it is impossible to give them
chronologically, or even to assign them properly to the earlier or

access to the Portsmouth Collection, and also he seems to have confused school years, which
omit the summer months, with calendar years.

My own table of dates is compiled from manuscript statements made by Conduitt and
Stukeley, as follows:

Left day schools and went to Grantham School when he was twelve.—As he was twelve
Christmas, 1654, I assume he went to Grantham in the autumn of that year.

Remained at Grantham four years.—He would thus stop school in the spring of 1658.

Returned to Grantham for three-quarters of a year.—That is, one school year and, as he
was admitted to College in June, 1661, he went to Grantham in the autumn of 1660.

He thus passed five school years at Grantham, and two years and a summer at home be¬
tween his two periods in school.

Brewster (Memoirs of Sir Isaac Newton, Edinburgh, 1855, vol. I, pp. 7, 13, and 14) s,q
contradicts himself that he cannot be relied upon.

ISAAC NEWTON

later of his two school periods; in fact, because of the confusion as
to the time when he was at Grantham, some of the stories told of him
may be placed as happening at Woolsthorpe.

The Old King’s School at Grantham, 9 to which Newton was sent
and where he was prepared for Cambridge, was established in 1528
during the reign of Henry VIII by Richard Fox, Bishop of Win¬
chester and favourite minister of Henry VII. The building is now
abandoned as a school, but it is still standing and is used regularly for
an assembly hall; carved on its walls, amongst many other boys’
names, may still be seen that of I. Newton, mute witness of his
boyish days. The foundation also included a house and offices for the
master; and the churchyard, directly on to which the school opened,
did service for a playground. The then Headmaster, Henry Stokes,
was esteemed to be an excellent scholar and a good teacher. He, if
we can believe the story, became so proud and fond of Newton that,
when the day came for the boy to leave school, he “with the pride of
a father, placed his favourite pupil in the most conspicuous part of
the school, and having, with tears in his eyes, made a speech in praise
of his character and talents, held him up to the scholars as a proper
object of their love and admiration.” 10

While at Grantham, during term time, Newton lodged with an
apothecary, named Clark, whose house “was next to the George Inn
northward in High Street, which was rebuilt about sixteen years
ago [1711].” The reason for selecting this lodging was due to the
intimate friendship of Mrs. Clark and Newton’s mother, and it
proved to be a happy choice, for the Clark family exercised a whole¬
some influence over the boy. They gave him the liberty to indulge
his passion for making mechanical toys and models, they provided
him with a study and books, and seem to have directed wisely his
studies and life. Mr. Clark was certainly the cause of the boy’s early
interest in chemistry; and his later absorption in his chemical lab¬
oratory at Cambridge may have had its first incentive in the com¬
pounding of drugs and chemicals in the apothecary shop. Dr. Clark,
M. D., a brother of the apothecary, was the mathematical usher at the
school, and had the supervision of his most important subject. This

^ This school has an honourable record. It carries on its rolls the names of several very
distinguished men, such as Sir William Cecil, the statesman, Dr. Henry More, the philoso¬
pher, Dr. Newcome, Master of St. Johns, Sir Isaac Newton, Colley Cibber, the actor and poet-
laureate, etc.

10 Isaac Newton: 1642-1727. Ed. by W.. J. Greenstreet, London, 1927, p. 142. This is a
collection of essays, on Newton and his work, published to commemorate the bicentenary
of his death.

EARLY YEARS

Dr. Clark was a pupil of the famous Henry More of Christ College,
who was himself a Granthamite, having been born in Mr. Bellamy’s
house over against the house of Dr. Stukeley to whose recollections
we owe most of our knowledge of Newton’s youth. A monument in
the church of Grantham to Gabriel More describes him as “Nephew
of Henry More, D. D. of Xts Col. in Cambridge by his learned writ¬
ings in divinity and philosophy one of the greatest glories of our
church and nation.” Later, at Cambridge, Newton became an in¬
timate associate of Henry More, who exerted on him a profound in¬
fluence in both philosophy and religion. And, lastly, a stepdaughter
of Clark was his most intimate friend and playmate. We can thus
give to this family the honour of contributing much to the education
and character of Newton.

Conduitt relates a story of Newton’s school days which is im¬
portant as it illustrates one of his most characteristic traits. All dur¬
ing his life, he required an external stimulus to arouse his latent
power, and to exert himself to complete his work or to make public
the fruits of his meditation. When he first went to the school at
Grantham, he was placed in the lowest form and continued to be
negligent in his studies: “When he was the last in the lowermost
class but one, the boy next above him, as they were going to school,
gave him a kick in his belly which put him to a great deal of pain.
When school was over Newton challenged him to fight, and they
went into the churchyard. While they were fighting the Master’s
son came out, and encouraged them by clapping one on the back,
and winking at the other. Isaac Newton had the more spirit and
resolution, and beat him till he would fight no more. Young Stokes
told Isaac Newton to treat him like a coward and rub his nose
against the wall, and accordingly Isaac Newton pulled him along
by the ears and thrust his face against the side of the church. De¬
termined to beat him also at his books, by hard work he finally suc¬
ceeded, and then gradually rose to be the first in the school.” 11

We fortunately have preserved for us a contemporary account of
Newton’s boyhood interests and occupations which Dr. Stukeley
gathered shortly after Newton’s death from some of his schoolmates
who were still alive and from unquestionable tradition. It is so in¬
teresting and so quaintly expressed that it is well worth quoting in
full: 12

11 Portsmouth Collection.

12 Portsmouth Collection. Also published in Turnor, pp. 176-178.

ISAAC NEWTON

“Every one that knew Sir Isaac, or have [sic] heard of him, re¬
count the pregnancy of his parts when a boy, his strange inventions,
and extraordinary inclination for mechanics. That instead of play¬
ing among the other boys, when from school, he always busied him¬
self in making knick-knacks and models of wood in many kinds.
For which purpose he had got little saws, hatchets, hammers, and
all sorts of tools, which he would use with great dexterity. In par¬
ticular they speak of his making a wooden clock. About this time,
a new windmill was set up near Grantham, in the way to Gunnerby,
which is now demolished, this country chiefly using water mills.
Our lad’s imitating spirit was soon excited and by frequently prying
into the fabric of it, as they were making it, he became master enough
to make a very perfect model thereof, and it was said to be as clean
and curious a piece of workmanship, as the original. This sometimes
he would set upon the house-top, where he lodged, and clothing it
with sail-cloth, the wind would readily turn it; but what was most
extraordinary in its composition was, that he put a mouse into it,
which he called the miller, and that the mouse made the mill turn
round when he pleased; and he would joke too upon the miller
eating the corn that was put in. Some say that he tied a string to the
mouse’s tail, which was put into a wheel, like that of turn-spit dogs,
so that pulling the string, made the mouse go forward by way of re¬
sistance, and this turned the mill. Others suppose there was some
corn placed above the wheel, this the mouse endeavouring to get to,
made it turn. Moreover Sir Isaac’s water clock is much talked of.
This he made out of a box he begged of Mr. Clark’s [his landlord’s]
wife’s brother. As described to me, it resembled pretty much our
common clocks and clock-cases, but less; for it was not above four feet
in height, and of a proportionable breadth. There was a dial plate at
top with figures of the hours. The index was turned by a piece of
wood, which either fell or rose by water dropping. This stood in the
room where he lay, and he took care every morning to supply it
with its proper quantity of water; and the family upon occasion
would go to see what was the hour by it. It was left in the house long
after he went away to the University.

“I remember once, when I was deputy to Dr. Halley, Secretary at
the Royal Society, Sir Isaac talked of these kind of instruments,—
that he observed the chief inconvenience in them was, that the hole
through which the water is transmitted, being necessarily very small,
was subject to be furred up by impurities in the water, as those made

EARLY YEARS

with sand will wear bigger, which at length causes an inequality in
time.

“These fancies sometimes engrossed so much of his thoughts, that
he was apt to neglect his book, and dull boys were now and then put
over him in form. But this made him redouble his pains to overtake
them, and such was his capacity, that he could soon do it, and out¬
strip them when he pleased; and it was taken notice of by his master.
Still nothing could induce him to lay by his mechanical experiments:
but all holidays, and what time the boys had allowed to play, he spent
entirely in knocking and hammering in his lodging room, pursuing
that strong bent of his inclination not only in things serious, but
ludicrous too, and what would please his school-fellows, as well as
himself; yet it was in order to bring them off from trifling sports,
and teach them, as we may call it, to play philosophically, and in
which he might willingly bear a part, and he was particularly in¬
genious at inventing diversions for them, above the vulgar kind. As
for instance in making paper kites, which he first introduced here.
He took pains, they say, in finding out their proportions and figures,
and whereabouts the string should be fastened to the greatest ad¬
vantage, and in how many places. Likewise he first made lanterns
of paper crimpled, which he used to go to school by, in winter
mornings, with a candle, and tied them to the tails of the kites in a
dark night, which at first affrighted the country people exceedingly,
thinking they were comets. It is thought that he first invented this
method; I can’t tell how true. They tell us too how diligent he was
in observing the motion of the sun, especially in the yard of the house
where he lived, against the walls and roofs, wherein he would drive
pegs, to mark the hours and half hours made by the shade, which by
degrees from some years observations he had made very exact, and
any body knew what o’clock it was by Isaac’s dial, 13 as they ordinarily
called it; thus in his youngest years did that immense genius discover
his sublime imagination, that since has filled, or rather compre¬
hended the world.”

It is natural that these reminiscences should dwell on Newton’s
handicraft and give us so little of his mental life. The outward habits

13 Several of these dials are still to be seen on the wall of the Manor House.—According
to Conduitt: “To the time of his death he retained this custom of making constant observa¬
tions in the rooms he chiefly used where the shade of the sun fell; and I have often known
him both at Kensington and in St. Martin’s Street, when anyone asked what o’clock it was,
tell immediately by looking where the shadow of the sun touched as exactly as he could have
by his watch.”

ISAAC NEWTON

and occupations of a boy are easy to observe and to remember, but to
appreciate his inner life is, at best, a difficult matter; of one like
Newton, who so jealously and persistently guarded the sanctuary of
his mind, it would be next to impossible to form a judgement. It is
probable that he never met a boy or a girl with whom he shared the
confidences of his thoughts. We do know, however, that he early
acquired the habit of reading and of recording his thoughts in note¬
books, a habit which continued to grow with the years to such an ex¬
tent that towards the end of his life his nephew, Mr. Conduitt, tells
us that he was hardly ever without a book or pen in his hand. His
first source of reading lay in that parcel of old books stored in Mr.
Clark’s attic, but unfortunately no one was interested enough to
record their titles. Newton should not be characterised as absent-
minded, but he was subject to fits of deep abstraction when pro¬
foundly engaged on a problem, and this habit of prolonged and in¬
tense meditation began in his boyhood. We have the stories of his
days on the farm when he became absorbed in his books and forget¬
ful of the duties assigned to him. In particular, it is told of him that
once, when he was riding home from Grantham, he dismounted
to let his horse walk up Spittlegate Hill, just beyond the town, and at
the top, he turned to mount again, only to find that his horse had
slipped away, leaving the bridle in his hand. On another occasion,
his friend, Dr. Stukeley, called on him. Newton was out, but the
table was laid for dinner. Dr. Stukeley lifted the cover, ate the dinner,
and then replaced it on the dish. When Newton appeared later he
greeted his friend and sitting down he, too, lifted the cover—“Dear
me,” said he, “I thought I had not dined, but I see I have.” 14

Newton was not only expert with tools but he had a talent for
drawing which he apparently cultivated by himself, as his writing
master at Grantham, Old Barley as he was called, seems not to have
had any ability in that art. Mr. Clark told Dr. Stukeley, many years
later, that the whole wall of his lodging room was still full of the
drawings he had made upon it with charcoal: “There were birds,
beasts, men, ships, and mathematical schemes, and very well de¬
signed.” Dr. Stukeley also states that he furnished his room, at
Woolsthorpe, with portraits, some copied from prints and others
drawn from life which were placed in frames of his own making.

14 Greenstreet, p. 142.—This trick played upon him is usually laid in Cambridge; but,
as Stukeley was only ten years old when Newton left Cambridge, it must be referred, if true,
to his later days in London.

EARLY YEARS

As Newton is represented as singularly indifferent to, and even
contemptuous of, all forms of art, we are left in doubt whether his
habit of drawing resulted from his fondness for handicraft, or from
an appreciation of the pictorial arts. If we can judge from his library,
he had no interest in belles-lettres, and Conduitt states that, in his
latter days, he often expressed a contempt for poetry; yet Newton
once astonished him by remarking that he had, when young, excelled
particularly in making verses. Surprising as this statement may be,
we have a specimen of his skill. Under a picture of King Charles I
hanging in his room, he wrote, Stukeley tells us, these verses which
Mrs. Vincent 15 repeated from memory:

“A secret art my soul requires to try,

If prayers can give me, what the wars deny.

Three crowns distinguish’d here in order do
Present their objects to my knowing view.

Earth’s crown, thus at my feet, I can disdain,

Which heavy is, and, at the best, but vain.

But now a crown of thorns I gladly greet,

Sharp is this crown, but not so sharp as sweet.

The crown of glory that I yonder see
Is full of bliss and of eternity.”

These are very good verses in the fashion of the day to be written
by a boy of his age, and I accept his statement of his skill, as I believe
he could excel in any undertaking to which he applied his mind or
hands. In addition to their skill, these verses are a convincing ev¬
idence that the boy was brought up in a family devoted to the Church
of England and the Royalist cause. The piety attributed to the
Martyr King is typical of the time, and we may be certain that he was
opposed to the prevalent sympathy of the countryside to Cromwell.
This is the more significant because, in later life, he became a con¬
vinced Whig and anti-Jacobite; and, while he remained a com¬
municant of the Church of England, he adopted a rational protes-
tantism very similar to that of Milton.

Newton was characterised by his chroniclers as a normal and
wholesome boy and this is undoubtedly true if it be understood as
referring to a moral and disciplined mind and temperament. But he
was certainly anything but the usual type of country boy. No better

15 Her maiden name was Storey; she was a stepdaughter to Clark and Newton’s intimate
friend while he lived with the Clarks.

ISAAC NEWTON

sketch of his character as a youth has been given than that of Miss
Storey, who knew him more intimately than anyone else and who
apparently was a keen judge. She told Stukeley that: “Sir Isaac was
always a sober, silent, thinking lad, and was never known scarce to
play with the boys abroad, at their silly amusements; but would
rather choose to be at home, even among the girls, and would fre¬
quently make little tables, cupboards, and other utensils for her and
her playfellows, to set their babies and trinkets on.” These traits were
undoubtedly innate; but they were strengthened by two influences
which have escaped the notice of his biographers, as none of them
considers the effect on his character of the circumstances of his birth
and of the times.

During his early years, Newton must have been physically weak
because of his premature birth. He would be unable to compete in
the active games and contests of his rough companions in the little
country schools he first attended, and the only recourse of such a
boy to escape the humiliation of being taunted as a weakling, and to
avoid the physical torments inflicted by childish bullies, was to iso¬
late himself. It is hard to realise the mental suffering such a child
may undergo and how likely it is to fix upon him the habits of de¬
tached meditation and self-absorption, which may become so strong
as to create an inability for ingenuous friendships. And, at home, he
grew up in a lonely farmhouse situated in a countryside only
slowly recovering from the terrors of a protracted and bitter civil war,
and with no protection from the frights of his imagination except
that of his grandmother and such unreliable labourers as could be
hired.

He must have been familiar with the incursions of rough raiding
parties after provisions and plunder, and he and his grandmother,
suspected of sympathy to the royal forces, must have been frequently
forced to evade embarrassing questions of the Commonwealth
soldiers and of the local magistrates. In addition to these induce¬
ments to cultivate silence and reserve he would have for companions
at home, also, only the children of his few neighbours, their rough
play made still rougher by imitation of the lawless deeds of the
soldiers. Such a child could not be in sympathy with them and
would turn from outward companionship to the solace of lonely
meditation.

Timidity and diffidence, added to a character of high purpose and
essential nobility, will account for his hatred of cruelty, his sym-

EARLY YEARS

pathy and generous aid to those who might be in trouble. He pre¬
served a steadfast and deep affection for members of his family
with whom he felt unconstrained and at ease, but in general society
he was cold and formal, and was singularly unable to form intimate
friendships. But he had to contend with an even more serious de¬
fect of temperament. Though his biographers have earnestly tried to
make of him a national monument not only of genius, but also of
virtue, the fact is that he had a morbidly suspicious and secretive
mind which must have had its source in a form of vanity, or in an
exaggerated sensitiveness of personal honour. In spite of a strong
will and the exercise of self-discipline, he was subject to peevish out¬
breaks of ill-temper, and of suspicious injustice even towards those
who were his best friends. On such occasions he stooped to regretta¬
ble acts which involved him in a succession of painful controversies
that plagued his life, robbed him of the just fruits of his work, and
disheartened his sincere admirers.

His early love of solitude, his delight in the fancies of his imagina¬
tion, his manual dexterity, and his habit of concentrated thought in¬
creased steadily with his years. They were the early evidence of his
future power; and they give the clue to the apparently sudden, and
otherwise mysterious, efflorescence of his enormous mental ability.

While Newton was at home helping his mother manage the farm,
he began to keep note-books; Conduitt mentioned that two of these
records of his youthful activities had been preserved all his long life
and were desposited with the family papers. Brewster, who ex¬
amined the Portsmouth Collection almost a century ago, found only
the second, and later, note-book. When, or how, the other was lost is
unknown, but by one of the strange tricks of fate, the first little
volume, after dropping out of sight for more than a century, has
recently been found amongst the manuscripts of the Pierpont Morgan
Library in New York. Selected portions have now been published
by Professor David Eugene Smith. 16 As he kindly gave me a photo¬
static copy with the permission of the Trustees to use what portions
I desired, I can include some of the interesting items of this relic of
Newton’s early days.

The book is about 2% by 4% inches and has a title-page: “Isaacus
Newton hunc librum possidet. teste Edvardo Seeker, pret: 2 d ob.
r659.” The contents are a curious collection of odds and ends brought

10 Greenstreet, p. 1 6 .

ISAAC NEWTON

together by a boy of an unusually acquisitive mind who is planning
to do large things but without any settled purpose. Thus, his love of
orderly detail is shown by a catalogue running to forty-two pages,
divided under sixteen heads, of such lists as “Arts, Trades, and
Sciences,” “Birds,” “Household stuffe,” “Minerals,” etc. There are
also samples of perpetual calendars, astronomical tables, and solu¬
tions of geometrical problems. Like many boys, he dabbled in
languages and invented a scheme of phonetic writing. On one page
he sets down his key of phonetic spelling and on the next page he
gives a sample letter spelled in both ways. The note is as follows:

“Loving Friend.

“It is commonly reported that you are sick. Truly I am sorry for
that. But I am much more sorry that you got your sickness (for that
they say too) by drinking too much. I earnestly desire you first to
repent of your having been drunk and you to seek to recover your
health. And if it please God that you ever be well again, you have a
care to live healthfully and soberly for time to come. This wfill be
very well pleasing to all your friends and especially to

Your very loving friend

I. N.”

Whether or not Newton had a bibulous friend, the note probably
is expressive of his own character and is thus worth preserving.

The most interesting, perhaps, of the items in this book, are those
referring to drawing and the making of pigments, as they show the
great interest he took in the art, and to the chemical and medicinal
recipes which he jotted down. A sample of each will be sufficient.

“A sea colour. Take privet berries when y e sun entreth into Libra,
about y e 13th of September, dry y m in y e sunn; then bruise them &
steepe y m in allum water, & straine y m into an earthen poringer y*
is glazed.”

“To make his powder to purge the head. Take vinger of the best,
Orris powder of each halfe a dram; Pellitory of Spaine, & white
hellebore, of each halfe a dram; All these into a fine powder & searce
them well & add to them two dropps of oyle of Anniseeds. And
when you will use it take the quantitie of a barley corne & snuff it
upp into yo r nose & it will cause a snezing, whereby it purgeth the
head from all superfluous humo s strengtheneth the memory causeth

EARLY YEARS

a cleare sight & is good for the thikness of hearing taken as above-
said every other morning.”

The second and third parts of the book were written at college and
are much more mature. He drew up a scheme to reform spelling,—
a matter of great importance in the seventeenth century,—that shows
incidentally that he had some familiarity with the Hebrew alphabet.
His interest in making sundials was still keen and he had passed from
the cut-and-try stage to that of calculation. There are included in the
mathematical section five pages of solutions of problems, two pages
of notes on the Copernican system, and two more pages devoted to
the working out of an elaborate ecclesiastic calendar. These casual
notes on the Copernican system should be regarded as a most precious
document for they are the germ from which developed his discovery
of the law of universal gravitation.

The second of Newton’s early memorandum books is still to be
seen in the Portsmouth Collection . On the first page is the inscrip¬
tion: Quisquis in hunc librum Teneros conjecit ocellos. Nomen sub-
scriptum perlegat ipse nomen. Isaac Newton. Martii 19, 1659.” And
on the next page there is the heading: “Utilissimum Prosodiae Sup-
plementum. The body of the notes contains rules of grammar.
The remainder of the book is a running expense account. Most of
these items refer to his college days and, as they shed some light on

that period of his life, a selection from them will be given in the
next chapter.

While Newton was preparing for college, he again lived with the
Clarks, and his affection for Miss Storey deepened into love and an
to be married. On the authority of Dr. Stukeley, who
had a long conversation with her in her old age: “Sir Isaac and she
being thus brought up together, ’tis said that he entertained a love
for her; nor does she deny it: but her portion being not considerable,
and he being a fellow of a college, it was incompatible with his for¬
tunes to marry; perhaps his studies too. ’Tis certain he always had a
kindness for her, visited her whenever in the country, in both her
husbands days, and gave her forty shillings, upon a time, whenever
it was of service to her. She is a little woman, but we may with ease
discern that she has been very handsome.” 17

When his tutoring was completed, he left home as a shy and dif¬
fident country boy and entered the busy and populous life of Cam¬
bridge without acquaintances and without influence. His preparation

17 Portsmouth Collection.

ISAAC NEWTON

seems to have been somewhat defective; and his first years were
passed without distinction, and in such loneliness that he seized every
opportunity to return home where he would be free to indulge in his
private meditations.

CHAPTER II

CAMBRIDGE UNIVERSITY. STUDENT LIFE.

EARLY DISCOVERIES
1661-1669

C ambridge University, which now became the home of the
young Newton, had like the nation suffered terribly from
the two decades of strife and turmoil of the Civil War. Ex¬
hausted in funds and deprived of many of its leading Fellows, the
University during the period of his undergraduate life was badly dis¬
organised; the number of students had been greatly reduced, their
discipline had been relaxed and their instruction interrupted.

Cambridge had been steadfast in its devotion and loyalty to Charles
I. Even while he was Prince of Wales, there had been an attempt
made to elect him Chancellor of the University at the preposterous
age of twelve years. Although the plan was finally defeated and
every effort was made to consign it to oblivion in order to save the
royal feeling of humiliation, yet the episode had its bearing on the
future of the University as it focused the attention of the nation on
the academic subserviency to the Crown. The more acute and ob¬
servant minds in the University may have feared the ominous aspect
of the times and the effects of the taciturnity and obstinacy of
Charles’s disposition, but hope and loyalty prevailed and the Uni¬
versity was enthusiastic at his accession in 1625. His father, in his
pedantic way, had been eager to be recognised as a scholar and to
engage in learned discussions. So long as the University respected
his obstinate belief in the divine right of kings and regarded him
as its undisputed master, he was more than willing to be known as
its patron and benefactor. Charles, in the early years of his reign,
pursued the same policy and so encouraged Cambridge to hope for
a further period of prosperity. As a reward for royal favours both
father and son were permitted, and even urged, to meddle in matters
of academic policy. In particular, they indulged more and more fre¬
quently in the exercise of arbitrary power in appointing heads and
fellows of the colleges by Royal Mandate; though such appointments

ISAAC NEWTON

were contrary to custom and, in many cases, to the statutes, they were
ratified with servile complacency in the hope of arousing generosity.
This grave infringement on academic rights introduced not only the
evils of court favouritism but gave rise to parliamentary hostility and
intervention. The first interference in University affairs by the Com¬
mons was directed against this exercise of Royal Mandate. An Act
“to prevent corruption in the presentations and collations to benefices
and in elections to headships, fellowships, and scholars places, in Col¬
leges and Halls” was read a second time in the House and referred to
a Committee on February 23, 1629; and it would doubtless have be¬
come law if Parliament had not been dissolved in the following
month. 1

The increasing disposal of the church patronage of the University
by the Crown was perhaps an even more dangerous interference in
academic privilege. Both Oxford and Cambridge still preserved the
traditional education preparatory to the learned professions of di¬
vinity, law, and physic. And, of these, divinity was undoubtedly of
the greatest importance. Most of the Fellows of the colleges were in
orders, and it was largely by supplementing the small stipends of
their fellowships by the income from ecclesiastical livings that they
met their expenses. Thus, if church patronage fell into the hands of
the Crown so also the Fellows would be compelled to look to it
rather than to the University authorities for appointments and prefer¬
ment. Archbishop Laud, who was determined at all hazards to
strengthen the hierarchy of the Church of England, eagerly seized on
the power of Church patronage as a means to maintain the estab¬
lished Church in the Universities and to counteract the spread of
Puritanism. Thus the Fellows were held in subjection and those
who were recalcitrant, however able they might be in scholarship,
were forced to submit or resign.

The stirring of the new knowledge on the continent which re¬
sulted from the scientific ideas of Galileo and Descartes had not seri¬
ously affected Oxford and Cambridge. Not even the influence of
Francis Bacon, who had eagerly adopted the new inductive philoso¬
phy and become its foremost expounder and advocate and who had
no peer in his loyalty to his Alma Mater, Trinity College, could shake
the grip of the traditional Aristotelian philosophy which had fastened
itself in the schools of divinity.

This was not so in Italy where the scientific renaissance was in full

1 Mullinger, History of Cambridge University, vol. Ill, p. 99.

CAMBRIDGE UNIVERSITY

flower and had spread to France and Holland. There, the revival
of humanism and the growth of experimental science had broken
the power of mediaeval philosophy and had become clearly indicated
by a new interest in Platonism. Italy was the centre of culture and
learning and eager students from all the other countries flocked to
its universities. The relatively few Englishmen who made the pil¬
grimage were unable on their return to shake the conservative atti¬
tude of their own universities and they found little sympathy with
their new ideas and few facilities for their work. The libraries were
wretchedly deficient and inadequately housed; while astrology and
superstition were almost as prevalent as they were in the Dark Ages.
As an example of the credulity which existed even in Cambridge,
this story may be cited. In 1629, “both town and university were alike
disquieted by the occurrence of a singular natural phenomenon. On
Midsummer eve, a volume containing three pietistic treatises was
found in the belly of a codfish exposed for sale in Cambridge market.
One of the bedells thought the incident sufficiently remarkable to be
brought under the notice of the vice-chancellor, by whom it was
looked upon as of the greatest gravity, and an incident, which a cen¬
tury later would have been regarded with no other feeling than that
of amusement, appeared to both the learned and the vulgar of Cam¬
bridge an event fraught with dismal portent. The appearance of
some gigantic comet in the heavens could hardly, in fact, have been
the occasion of greater dismay.” 2 Thomas Fuller, at this time a
bachelor at Queens, relates the circumstances in a manner which
shows that his keen sense of the ludicrous enabled him to rise superior
to the superstition of his time. The book, he tells us, “was wrapped
about with canvas, and probably that voracious fish plundered both
out of the pocket of some shipwrecked seaman. The wits of the uni¬
versity made themselves merry thereat, one making a long copy of
verses thereon, whereof this distich I remember:

‘If fishes thus do bring us books, then we

May hope to equal Bodlyes library.’

But whilst the youngsters disported themselves herewith, the graver
sort beheld it as a sad presage.” Among those of the 'graver sort’
was the exemplary master of Sidney, Dr. Samuel Ward, who thought
the prodigy worthy of being reported in all its details to his friend,
Archbishop Ussher. 3

2 Mullinger, Vol. Ill, p. 71. 3 Ibid., Vol. Ill, p. 71.

ISAAC NEWTON

The scholarly work which issued from the University was mostly
confined to controversial treatises on theological or philosophical sub¬
jects, of large bulk but of small value. So the scholar, if he would
win recognition and advancement, was pretty much restricted to ex¬
haust his energies in making new commentaries on the classical au¬
thors or tortuous interpretations of the Scriptures. In mathematics,
natural philosophy, and modern history there was hardly any inter¬
est. The first direct influence of Bacon’s plea for a more liberal cur¬
riculum was shown by the establishment of a lectureship on modern
history by Fulke Greville, first Lord Brooke. The significant feature
of the ordinance was that: “A foreigner was to be considered eligible,
but no one ‘in holy orders’ was to be considered so, as well ‘because
this realm affordeth many preferments for divines, few or none for
professors of profane learning, the use and application whereof to
the practice of life is the main end and scope of this foundation; and
also because this Lecture must needs hinder a divine from the studies
and offices of his calling due to the Church.’ ” 4 It seems incredible to
us that contemporaneous history should have been absolutely neg¬
lected in a great university; but it was a fixed tenet of scholars that
all the examples of human wisdom and human folly had been per¬
fectly illustrated by classic writers and profit could be obtained only
by study of their works. As late as the eighteenth century, a long
and heated controversy was waged between Bentley and the fore¬
most scholars of England as to whether any modern man had been
the peer of the great heroes of Greece; and the consensus of opinion
was that there had been no one equal to them in either intellect or
character. Cambridge could not provide a person qualified for the
chair of history, and it was necessary to secure a young scholar from
Leyden.

The best type of the Cambridge scholar of the age can be illustrated
by Joseph Mede (1586-1638), Fellow of Christ’s College. He was
skilled both in the technical knowledge and in the philosophy of the
schools; he was conversant with the meagre mathematics current in
the University; he was an excellent modern linguist, and his knowl¬
edge of history and chronology was considered remarkable; he was
a profound theologian and an eminent classical scholar; and he was
an anatomist and a botanist. In addition to these varied accomplish¬
ments he was the ablest and most effective teacher in all the Univer¬
sity, and he maintained a voluminous correspondence with all sorts

4 Mullinger, Vol. Ill, p. 84.

CAMBRIDGE UNIVERSITY

of people who sought his advice on state and political affairs. Yet
this paragon of scholars used his valuable time and energy in com¬
piling a large quarto volume in which a vast number of Greek,
Latin, and English words were traced back to their supposed He¬
brew roots. There was a sort of magnificent simplicity and direct¬
ness in the philology of those days which puts to shame the confused
efforts of our modern searchers for verbal roots. All the races of
mankind were assumed to have descended from Adam and Eve, so,
since they spoke with the Hebrew tongue, all words in all languages
could be traced back ultimately to that prototype if one had only
sufficient ingenuity and diligence. Those naive philologists remind
us of the modern biologists who assume an ancestral protozoon and
trace all the species of life to that mythical ancestor. Both assump¬
tions are equally futile, for both sources lie buried in the oblivion of
time.

But it was not so much as a scholar and teacher of profane subjects
that Mede impressed his influence on his contemporaries. His monu¬
mental work was his Clavis Apocalyptica, originally written in Latin
in 1627 and translated into English in 1642 by Richard More. The
author’s purpose was to form a connected and chronological sequence
of actual and prophetic events from the mystical rhapsody of the
Book of Revelations; on this dream he lavished all his profound eru¬
dition and critical acumen. “The Clavis won for its author the regard
of Hartlib and the praise of nearly all learned Holland; it modified
the religious belief of John Milton; and taking rank, for more than
a century, as a classic, it exerted an influence on theological thought
which no English writer on the period appears adequately to have
recognised.” 0 But what is significant to us is that the book had a
direct influence on Newton, who was profoundly interested in such
exegesis and referred to Mede in his own religious writings as his
guide in prophetic interpretation.

Another book, the Life of Jacob Boehme by Durand Hotham, is
known to have received the careful attention of Newton. The mysti¬
cal doctrines of Boehme had a great influence in England; his aver¬
sion to theological disputes and to formal services seemed a haven of
rest to those wearied by the controversies between the ritualistic Ro¬
man Catholic and English Churches, and bleak Puritanism,—a refuge
where one could worship in seclusion, directed by the dictates of the
inner light.

5 Mullinger, Vol. Ill, p. 24

2 6

ISAAC NEWTON

Space will not permit a detailed discussion of the tangled and dis¬
astrous history of the University while it was almost ground to dust
between the dissensions of the Royal and Commonwealth parties.
The eleven years, which followed the dissolution of Charles’s third
Parliament in 1629, have been described as the darkest hour of Prot¬
estantism, whether in England or in the world at large. In Cam¬
bridge a feeling of profound moral and intellectual depression set in,
caused by the suspension of freedom of discussion and enhanced by
the horrors of the plague of 1630 which drove great numbers of the
students out of town, practically stopped classes and study, and even
silenced temporarily the ardour of theological controversy.

That the University survived the spoliation by both the royalists
and the anti-royalists and not only regained, but soon surpassed, its
former prestige and wealth, is a witness to the stability of academic
institutions. Of all the causes which can threaten the existence of a
university, there is none so dangerous and so bitter as the combina¬
tion of political and religious opposition. Of the two, political hos¬
tility is much less serious than the attacks of those who regard the
teachers of youth as the perverters of their personal faith. Yet, so far
as I can recall, there is scarcely an instance of a university, once well
established, which has not been able to weather all the vicissitudes
of political and religious upheavals.

It is a surprising commentary on the kaleidoscopic swiftness of
the events which convulsed the nation and its seats of learning to
remember that they were compressed almost exactly into the nine¬
teen years between the birth and matriculation of Newton. By the
latter time the long ordeal was over and on Thursday, the 10th of
May, 1660, the Restoration was celebrated by the vice-chancellor and
the doctors in scarlet gowns, the regents, non-regents and bachelors
with their hoods turned, and the scholars in caps. Perhaps, there
was no more significant sign that the University had returned to its
traditional life and established customs than the general re-appear¬
ance of the student mortar-board cap in place of the round pile us
which had been required during the Commonwealth.

However important an understanding of the state of the Univer¬
sity, as a whole, may be in obtaining a correct background for New¬
ton’s life, it is even more necessary that an account should be given
of Trinity College, where he lived so long and which he so adorned.
Henry VIII had founded in 1546 one spacious college, for the main¬
tenance of a Master and sixty Fellows and Scholars, dedicated to the

CAMBRIDGE UNIVERSITY

Holy and Undivided Trinity. Queen Mary afterwards added twenty
Scholarships. During the reign of Elizabeth the foundation was com¬
pleted and the statutes of its government were formulated in the
most liberal spirit. Almost from its start Trinity College took a com¬
manding position, and during the reigns of Elizabeth and James I,
when unusual care was paid to merit in ecclesiastical appointments,
Trinity could claim as her sons the Archbishops of Canterbury and
of York, and seven others of the principal Bishops. So great was the
reputation of her resident Fellows for theological learning that no
less than six of them were among the translators of the Authorised
Version of the Bible. In public life she counted Francis Bacon and
Sir Edward Coke. In belles lettres many of the Elizabethan poets,
and later Cowley and Dryden were among her students. Finally,
her scholarship was held in such high esteem that her Fellows were
chosen to fill the Headships of the majority of the other Colleges of
the University.

The civil troubles, and the bigotry of the Puritans, fell more heavily
on Trinity than on any of the other Colleges. The revenues were dis¬
sipated, many of the ablest Fellows were ejected and those who re¬
mained were either inferior in ability or were depressed in spirit.
During the last half of the seventeenth century the College declined
in numbers and in reputation and the body of Fellows comprised
fewer able scholars than at any preceding or subsequent period.
When Richard Bentley became Master in 1700, he repeatedly ac¬
cused the Fellows and students of both sloth and drunkenness.

When Newton went to Cambridge Henry Feme was Master, but
his tenure of office continued only two years. He was succeeded by
John Pearson in 1662 and by Isaac Barrow in 1673; Bishop Monk, in
his life of Bentley, characterises them as “two of the brightest char¬
acters which grace the period of Charles the Second.” During their
short administrations the finances were improved, building was car¬
ried on, and stricter discipline exacted. Unfortunately, before the
better conditions had been established, Dr. Barrow was succeeded
by the Hon. John North (1677-1683) and he by the Hon. John Mon¬
tague (1683-1700). Both of them were weak men and their rule
lasted the remainder of the period of residence of Newton at Cam¬
bridge. Bishop Monk lays the decline of Trinity during the most
fruitful years of Newton’s life to the following causes: “First, the
acknowledged relaxation of discipline under the last two Masters,
Dr. North and Dr. Montague, had produced its never-failing conse-

ISAAC NEWTON

quences, in impairing both decorum and learning: secondly, that
distinguishing principle of Trinity College, admission to the found¬
er’s bounty upon the score of merit alone, had experienced an inter¬
ruption in the times of civil discord, when Fellows were appointed
by the nomination of parliamentary commissioners, and subsequently
of the Protector. After the Restoration, Charles the Second, being
probably urged to assume the same patronage as had been exercised
by the Usurper, frequently sent Royal mandates for electing to fel¬
lowships; which, though plainly contrary to their statutes, the So¬
ciety were constrained to obey. In the short reign of James the Sec¬
ond this exercise of arbitrary power was carried still further, every
vacancy among the fellowships being filled by mandatory letters
from the King. Although the College was delivered by the Revolu¬
tion from further invasions of its privileges, yet some of the intruded
Fellows, having obtained office by their seniority and not being in¬
debted to industry or learning for their preferment, wanted both
ability and disposition to encourage those qualifications in others. A
third cause of the depressed and languid state of Trinity College may
be found in the prevalent distaste for the old system of academical
study; people had begun to neglect and despise the learning of the
schoolmen, before a more vigorous and manly system of instruction
had been substituted.” 6

When the young Newton left Woolsthorpe in June, 1661, and went
up to Cambridge, he was engaged to marry Miss Storey. This obliga¬
tion may have come from a sincere attachment or it may have re¬
sulted from the sentimental excitement incident to leaving home and
early surroundings. Whichever may have been the cause, we have
no reason to suppose that he did not expect to fulfill that contract
when he had finished his education and had become financially able
to support a family. Fie would, we may presume, expect to follow
one of two professions; he could return to Woolsthorpe and as a
small gentleman farmer manage his estates, or he might follow in
the footsteps of his uncle and stepfather, take orders and become a
parish priest. One can but wonder whether, if such had been his
fate, he would have lived an obscure life, respected by his neighbours
for ability and piety, or whether his genius for natural philosophy
would have developed in spite of his occupation. It is, to me, a prac¬
tical certainty that no circumstances could have repressed his creative
ability. But all doubt as to what was to be his career was quickly set-

6 Monk, Life of Richard Bentley, London, 1833, vol. I, p.. 143.

CAMBRIDGE UNIVERSITY

tied, and he drifted unerringly into the scholarly and celibate life.
At an age before most men have developed any maturity of thought,
he had seen the vision unfold in his mind of that universal force
which directs the cosmos,—he had solved one of the most baffling
problems of the ages. It is no wonder, then, that his engagement to
Miss Storey faded into mutual esteem and that he gave up all idea
of a rural and family life. Instead, he remained at Cambridge for
nearly forty years, the first seven years in statu pupillari until he re¬
ceived the degree of Master of Arts; the remaining time he spent as
Fellow of Trinity College and Lucasian Professor of Mathematics.

During the period of his undergraduate days he would be under
the direction of his tutor and must have conformed to the customary
curriculum and rules of college. As soon as he had received an or¬
derly intellectual training and was relieved from that discipline, he
gave free rein to his creative genius and made in rapid succession his
masterly discoveries.

Our direct knowledge of Newton’s social life in Cambridge, even
allowing for his detachment from current affairs, is very scant; and
the record of his intellectual pursuits, owing to his secretiveness of
mind and his abnormal sensitiveness to criticism, is meagre and con¬
fused. He kept no diaries and his later personal notes, except for
scientific or theological meditations, are brief and hasty. His associ¬
ates, in his early days, were evidently not deeply impressed by him,
and even in later life there are surprisingly few references to him in
contemporary records. We are forced to rely mainly on the occa¬
sional reminiscences of Newton, himself, after he had become old,
and those which a few of his acquaintances committed to writing
after his death. Such reminiscences are always more or less untrust¬
worthy because of the unreliability of the memory and the tendency
to magnify the early achievements of subsequently great men in
order to make great boys of them as well. In Newton’s case this is
peculiarly true because of the concerted attempt of the English to
make of him a national hero, without a blemish and without a rival,
either morally or intellectually.

Picture the effect of Cambridge on a pious, reserved, diffident, and
suspicious lad, fresh from the restricted and intimate life of a village
and a country school, suddenly thrown into the distracting life of a
great university town. Newton would find also a very different Cam¬
bridge from the one which his Uncle Ayscough may have described
to him. It had but just passed through the hazardous and repressive

ISAAC NEWTON

experiences of the Puritan Commonwealth; and now it had suddenly
become boisterous and riotous with the license which had come in
with the Restoration.

Newton was not well, or even systematically, trained when he en¬
tered college where he was immediately placed in competition with
young men from the great public schools. Even his passion and skill
for mechanical construction, which would now find expression and
distinction in experimental science, was then deemed to be of little
significance in the educational plan. The problems, which we are
told absorbed his youthful attention, have been carelessly assumed
to be exercises in pure mathematics, but it is far more likely that they
had to do with the elementary arithmetical calculations relating to
simple trains of wheel-work, sun-dials, or other mechanical devices.
The fact that he shunned all forms of physical exercise, played no
games, and disliked boys, would not endear him to his fellow under¬
graduates. Neither would he appeal to the more studious men, as
he was not sociable, witty, or talkative by nature. In addition, he was
further handicapped by the fact that he was a Sizar and paid for his
tuition and board by performing such menial tasks as procuring food
from the kitchens, running errands, and waiting on his Tutor . 7
Lastly, his strict religious training and temperamental disgust for
all forms of moral laxity would further isolate him from society, for
the notorious looseness of morals of the Restoration had quickly
spread from the Court to London, and from there to the universities.
It is no wonder then that we can learn little about his college life, or
that he seized every opportunity of a vacation to hasten back to
Woolsthorpe where he was sure to find the sympathetic companion¬
ship of Miss Storey, of his family, and of his neighbours. We get a
very significant glimpse of his life from the fact that he was driven
out of his lodgings by the racket and riot of the companions of his
room-mate and, while wandering disconsolately through the quad¬
rangle, he met and agreed with another lad in the same trouble to
change partners and room together, in order to secure peace and
quiet.

7 This class of students were required to perform various menial services. The following
extract from the Conclusion Boo\ of Trinity College, while it affords an example of one of
their duties, will also serve to illustrate the rampant buoyancy of the academic youth at the
period of the Restoration.—“Jan. 16.1660/1. Ordered also that no bachelor of what con¬
dition soever, nor any undergraduate, come into the upper butteries, save only a Sizar that is
sent to see his Tutor’s quantum, and then to stay no longer than is requisite for that pur¬
pose, under penalty of 6 d. for every time; but if any shall leap over the hatch or strike a
butler or his servant, upon this account of being hindered to come into the butteries, he shall
undergo the censure of the Master and Seniors.” Edleston’s Correspondence, p. xli.

CAMBRIDGE UNIVERSITY

Brewster states that Newton had the advantage of letters of intro¬
duction from his uncle, the Rev. James Ayscough, to friends in Cam¬
bridge. This seems to be a purely imaginative statement, as we have
no record of any such letters or of his uncle having any friends in
Cambridge so many years after his graduation. Curiously enough
Brewster overlooked other and more influential friends. Stukeley
states that when Newton entered college “Dr. Babington was senior
Fellow of Trinity, a person of learning and worth. He was own
uncle to Mr. Vincent [and thus a close relative to Mr. Clark, the
apothecary, with whom Newton had lodged], and that seems to be
the reason why he went to Trinity College. The Doctor is said to
have had a particular kindness for him which probably was owing
to his own ingenuity .” 8 Also Henry More, the Platonist and one
of the most distinguished men in the University, was a native of
Grantham and would probably assist him; later, they became inti¬
mate and had a very considerable influence on each other’s thought.
But Barrow was undoubtedly the most steadfast and important fac¬
tor in his career: “The Doctor had a vast opinion of his pupil and
would frequently say that he truly knew somewhat of mathematics
still he reckoned himself but a child in comparison of Newton .” 9
With such powerful backing it is not surprising that Newton ad¬
vanced rapidly in his academic standing.

It is possible from several sources to present a rather more satis¬
factory narrative of Newton’s intellectual activities than of his social
life during his undergraduate days. We have a considerable knowl¬
edge of the current academic discipline from which to draw infer¬
ences; we have some of his own college note-books; and a few valu¬
able anecdotes have been preserved . 10 Conduitt is the source of two
anecdotes which have been generally accepted. The first is that Mr.
Ayscough gave a copy of Sanderson’s Logic to his nephew before he
left home and told him it would be the first book he would be re¬
quired to read. He studied it so thoroughly that, when he attended

8 Portsmouth Collection. Conduitt also notes that Humphrey Babington was one of the
Senior Fellows when Newton was elected Fellow and may have been a Senior before his
admission.

9 Stukeley, Portsmouth Collection.

10 The principal sources for this period are his nephew-in-law Conduitt’s Memoirs of
Newton which he sent to Fontenelle to correct statements made in his Eloge to the French
Academy; his MSS. which he collected for a proposed life of Newton but never finished;
Pemberton’s View of Newton’s Philosophy; and personal reminiscences of Newton himself
which are scattered in a number of books. Brewster, who had access to all these sources,
seems to have used little care in pointing out obvious errors and to have joined with New¬
ton’s uncritical eulogists in what De Morgan characterises “as their joint attempt to
create a self-sufficient genius before there had been any dawn.”

ISAAC NEWTON

the college lectures on the subject, he was more familiar with it than
was his tutor, Mr. Pulleyn. 11 So deeply impressed was the tutor by
this independent industry that he invited the boy to attend readings
of Kepler’s Optics which he was about to give to some Gentlemen
Commoners. Newton without waiting for the class took this book
home and so mastered it that when the readings were commenced,
the tutor again found the subject had been thoroughly grasped by his
pupil.

Conduitt’s second anecdote is that, in 1663, Newton bought a book
on judicial astrology at the Stourbridge Fair, a festival held each au¬
tumn near Cambridge, and he soon found that he could not under¬
stand the astronomical problems without some knowledge of trigo¬
nometry. In his perplexity, he then bought an English Euclid with
an index of all the problems. Having turned to two or three of those
which seemed the most likely to be pertinent, he found the demon¬
strations of the theorems so self-evident that he expressed astonish¬
ment that anyone should bother to prove them and he threw it aside
“as a trifling book.” When he found Euclid to be beneath his notice
he set himself to study Descartes’s Analytical Geometry but gave up
the attempt, as he found it to be quite beyond his depth. However,
he soon returned to it and, by constantly poring over the text bit by
bit, he mastered the whole work without assistance.

These stories are probably based on fact, but they are plainly mixed
in their dates and quite misleading. In the first place, however much
Newton’s mastery of Sanderson’s Logic before he went to college
may have impressed his tutor, it would require a stretch of the im¬
agination to see why the ability to read an elementary textbook on
logic should lead to an invitation to attend readings on an advanced
treatise on optics. No self-respecting tutor would recommend a boy,
who had no knowledge of geometry, trigonometry, or optics, to read
Kepler’s Optics.

The story connecting Euclid and astrology, as it is told, is also pat¬
ently absurd. It seems to have a basis of fact, as it was vouched for
by Newton’s friend, Demoivre, but if so, the date must be wrong.
The whole course of mathematics at the University was based on
Euclid’s geometry; it is probable that some acquaintance with it was
required for entrance, and it is certain that he must have studied the

11 Benjamin Pulleyn, Regius Professor of Greek from 1674 to 1686. This professorship
was one of the seven royal foundations established by Henry VIII in 1540. Its first incumbent
was Erasmus and it has since been graced by a long line of eminent men, among whom are
Widdrington, Barrow, Porson, Jebb, and Jackson..

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subject during his first two years at College. It is far more likely
that his purchases of the Astrology and the Euclid occurred at two
different times. It would be better to date back the Euclid incident
to his Woolsthorpe period in connection with some mechanical prob¬
lem which involved a geometrical solution. A desultory student,
looking for a royal road to learning, might well have glanced at one
or two theorems and, finding them easy, have childishly tossed the
book aside as beneath his serious attention. 12

Since the knowledge of Newton’s character and work is derived
by most persons solely from Brewster’s Life, it is necessary to prove,
as occasions arise, how uncritically he has confused many of the in¬
cidents of his life. For example, in order to prove that Newton owed
nothing to his teachers but reached the maturity of his genius entirely
by his own unaided effort, Brewster adds this anecdote to the two
just discussed. In 1664, three years after his matriculation Newton
was elected to a scholarship: “On this occasion he was examined in
Euclid by Dr. Barrow, who formed an indifferent opinion of his
knowledge, and hence he was led not only to read Euclid, but to
form a more favourable estimate of the ancient geometer when he
came to the interesting propositions on the equality of parallelograms
on the same base and between the same parallels.” 13 Dr. Barrow,
who was rated as having shown a compass of invention equal, if not
superior, to any of his contemporaries, Newton only excepted, and
who was Newton’s teacher and most generous friend and patron,
may very properly have made this criticism when Newton first en¬
tered college or when he first attended Barrow’s lectures on geometry
a year or so later. But, can anyone suppose that Barrow would con¬
sent to his election to a scholarship if Newton, after studying mathe¬
matics for three years, during which he had mastered Descartes’s
Geometry and the other most advanced analysis of the day, were still

12 Amongst the books of Newton’s library, recently discovered, is a copy of Euclid edited
by Barrow. If he ever thought Euclid “a trifling book,” he evidently changed his mind and
followed Barrow’s advice, “for the whole book is full of corrections and notes, most of
which give the propositions in algebraic notation, doubtless as a help in its study.” Cj
Greenstreet, Isaac Newton, p. 169.

13 Brewster, Vol. I, p: 24.—It should be noted that Demoivre, from whom the anecdote
originated, gave the year as 1663 so the Euclid incident could not have occurred at the schol¬
arship election. In justification of Brewster it should be noted that Conduitt confirmed the
incident and added that Barrow did not examine him in Descartes as he did not imagine
anyone could master it before knowing Euclid and Newton was too modest to mention
it. As Conduitt did not collect his materials till after Newton’s death we find a number
of errors in dates and contradictions in facts about these early events. My criticism of
Brewster does not rest on his inclusion of such anecdotes but on the fact that he does not
observe and correct their er r ors.

ISAAC NEWTON

deficient in Euclidean geometry ? And what is there either especially
attractive or difficult in the propositions on parallelograms such as to
arouse his interest or to change a priggish opinion that “the ancient
geometer” was a trifler?

This legend, that Newton had not studied Euclid during his under¬
graduate course and that he had read Descartes’s Geometry when he
first entered college and before he had any mathematical knowledge,
is a striking instance of Brewster’s uncritical attitude towards the
Newtonian myth. It is especially glaring in this instance as on the
preceding page he had quoted a statement of Newton which dis¬
credits the anecdote.

The fact of the matter is, Newton early in his career became one of
the great masters of the classical, or Euclidean, geometry both on ac¬
count of a passion for that form of mathematical expression and be¬
cause of the influence of Barrow. Pemberton, who knew Newton in¬
timately in his old age, has given us a valuable and convincing state¬
ment of his personal taste in mathematics. He says: “I found he had
read fewer of the modern mathematicians than one could have ex¬
pected. ... I have often heard him censure the handling geometri¬
cal subjects by algebraic calculations. He frequently praised Slusius,
Barrow and Huygens for not being influenced by the false taste,
which then began to prevail. . . . But Sir Isaac Newton has several
times particularly recommended to me Huygens’s style and manner.
He thought him the most elegant of any mathematical writer of
modern times, and the most just imitator of the ancients. Of their
taste, and form of demonstration Sir Isaac always professed himself
a great admirer: I have heard him even censure himself for not fol¬
lowing them yet more closely than he did; and speak with regret of
his mistake at the beginning of his mathematical studies, in applying
himself to the works of Descartes and other algebraic writers, before
he had considered the elements of Euclid with that attention, which
so excellent a writer deserves.” 14

Such a detailed discussion of Newton’s personal taste in mathe¬
matics and the time when he studied Euclid was useful, in my opin¬
ion, as it afforded an excellent and concrete illustration of the care
with which our sources for a life of Newton must be examined if a

14 Pemberton, A View of Sir Isaac Newton’s Philosophy. Preface., The portion italicised
by me clearly proves that Newton had studied Euclid before he undertook to read Descartes,
and regretted that he had not fully mastered that author before he turned to others. When
such a geometer as Newton regrets that he had not considered Euclid with the attention the
subject deserved we should take into account what standard of consideration would be in his
mind.

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just and accurate biography is to be written. The importance of such
a careful consideration has been excellently expressed by Leibniz:
“It is an extremely useful thing to have knowledge of the true origins
of memorable discoveries, especially those that have been found not
by accident but by dint of meditation. It is not so much that thereby
history may attribute to each man his own discoveries and that others
should be encouraged to earn like commendation, as that the art of
making discoveries should be extended by considering noteworthy
examples of it.” 15

When we are told that nothing is known of Newton’s studies, the
very obvious fact is overlooked that every undergraduate was re¬
quired to follow an outlined and graded course of instruction under
the direct guidance of his tutor, and there is no reason to suppose that
Newton was an exception to the rule. In those days a tutor not only
stood in loco parentis to his pupils, which means that he had the
right to punish for disobedience, but he also taught them person¬
ally. 10 From Newton’s note-books, some of his letters and conversa¬
tions, and from our knowledge of the course of study then in vogue,
we can give a reasonably accurate and full statement of his under¬
graduate work. As for science, the most important of his studies, we
can give an almost complete account.

From Newton’s own notes we know that he spent the first two
years at college learning arithmetic, Euclid, and trigonometry. He
also read or listened to lectures on the Copernican system of astron¬
omy. For most of his work after the Easter Term in 1663, he was
under the direction of Barrow, 17 the newly appointed Lucasian Pro¬
fessor, who also taught him natural philosophy and, most significant
of all, optics. This science, which for the first time offered to him a
serious opportunity to use his experimental skill, evidently fascinated
him and first brought out his latent powers of invention. In addition
to following the course of lectures on light, he read Kepler’s Optics
probably during the vacation, and that study was undoubtedly the
cause of his interest in telescopes and the properties of light. His mas¬
tery of the subject was so thorough that, when Barrow shortly after-

15 Historia et Origo Calculi Differentialis . Cf. Child, Early MSS. of Leibniz, p. 22.

16 “The Statutes of 1560 which were in force till 1844 state: Pupilli Tutoribus pereant,
honorumque paternum ac reverentiam deferant, quorum studium labor et diligentia in
illis ad pietatem et scientiam informandis ponitur. Tutores sedulo quae docenda sunt
doceant; quaeque etiam agenda instruant admoneantque.” Greenstreet, p. 146..

17 While the College records show that Pulleyn was his tutor when he entered Trinity,
it is probable that Barrow took over that office. I found in the Portsmouth Collection the
statement by Stukeley that Dr. Barrow was his tutor.

ISAAC NEWTON

wards published his lectures, he turned to his youthful pupil for
criticism and revision of the manuscript.

From a personal note-book (which contains an entry on the seventh
page dated Jan. 1663/4), we have definite information when he first
turned to the new analytical geometry invented by Descartes in which
the properties of lines and surfaces are expressed by algebraic equa¬
tions. We also learn that he attained his knowledge by studying the
standard texts on the subject by Oughtred, 18 van Schooten, 19 Vieta, 20
and Wallis, 21 as well as Descartes. During the dispute, many years
later, with Leibniz on the discovery of the calculus, Newton made the
following entry which ought to settle the question as it was not de¬
pendent on memory.

“July 4 > 1699.—By consulting an account of my expenses at Cam¬
bridge, in the years 1663 and 1664,1 find that in the year 1664, a little
before Christmas, I, being then a Senior Sophister, bought Schooten’s
Miscellanies and Cartes’s Geometry, (having read this geometry and
Oughtred’s Clavis clean over half a year before), and borrowed Wal¬
lis’s works, and by consequence made these annotations out of
Schooten and Wallis, in winter between the years 1664 and 1665. At
such time I found the method of Infinite Series; and in summer 1665,
being forced from Cambridge by the plague, I computed the area of
the hyperbola at Boothby, in Lincolnshire, to two and fifty figures
by the same method.

Is. Newton.

Thus Newton progressed naturally and systematically from the
mastery of algebra and geometry to the newer forms of analytical
geometry and trigonometry which he first began to study in the sum-

18 William Oughtred (1574-1660). His most important work which long remained a
classic text is his Arithmetical in numeris et speciebus instituto, clavis est. It contains his
rule for abridged multiplication which is still taught in arithmetic courses. His other works
are collected under the title: Opuscula mathematica hactcnus inedita.

19 Frans van Schooten (d. 1661) wrote elementary textbooks to popularise the algebraic
geometry of Vieta and Descartes.

Francois Viete or Vieta (i54°~i6o3)., Published in his Isagoge in artem analyticam
(1591) an explanation how algebra could be applied to geometrical problems. Used letters
to express both known and unknown terms and a notation for powers of terms.. From
his^time elementary trigonometry was familiar to mathematicians.

21 John Wallis (1616-1703), Savilian Professor of Geometry in Oxford, was undoubtedly
the foremost. English mathematician of his time. His most important work, the Arith-
metica Infinitorum, displays and greatly extends the methods of analysis introduced by
Descartes and Cavalieri. It became the standard work on the subject and is constantly re¬
ferred to by Fermat, Barrow, Newton, and Leibniz. His solution for finding the areas of
curves by the use of infinite series was so close to the discovery of the calculus that Newton
and Leibniz had principally to clarify and advance his method into a formal system.

CAMBRIDGE UNIVERSITY

mer of 1664 or about half a year before he graduated. There are also
amongst his notes calculations relating to musical scales, and observa¬
tions on the refraction of light, the grinding of lenses and their errors,
which bore fruit later; and lastly problems on extracting mathemati¬
cal roots which ultimately led to his discovery of the Binomial
Theorem. In all this work, he was greatly helped, as Stukeley tells
us, by his dexterity in drawing and handicraft. The extraordinary
thing to bear in mind, in this catalogue of his undergraduate studies,
is not so much that Newton thoroughly mastered these subjects as
that he so digested them and meditated upon their inherent possi¬
bilities that they awoke his creative powers. In a few short years, each
subject led directly and unerringly to a masterpiece of genius, and,
a still more astonishing fact, these years provided the germ of all his
discoveries.

Before leaving the subject of Newton’s scientific training, we
should pause for a moment to give a sketch of the extraordinary life
of Barrow who, if he just failed to become one of the “Immortals,”
should be honoured as the intellectual father of a Newton. No youth¬
ful genius could have had a more excellent teacher and patron than
did Newton, who owed to him his early training in science, phi¬
losophy and religion, his scholastic honours, and his professorship.
If the facts could be known we undoubtedly should have had a
charming record of kind acts and wise advice.

Isaac Barrow was born in 1630 in London, and was educated at
the famous Charterhouse. Endowed with a restless body and a vivid
mind, he so plagued his teachers and was so troublesome at home
that his father, with lack of parental vision, prayed that if it pleased
God to take away any of his children he could best spare Isaac.
From the Charterhouse he went to Cambridge and became Bachelor
of Arts, Trinity College, in 1648, and Fellow in 1649. He resided
there till 1655 when he was driven out of the country by the Inde¬
pendents because of his political and religious views. The next four
years were spent in travelling in Eastern Europe where he was at¬
tacked by pirates and had other exciting adventures. Shortly before
the Restoration, when conditions became safe for him, he returned
to England; was ordained to the ministry and elected professor of
Greek in Cambridge. In 1662 he became professor of geometry in
Gresham College; a position which he held for only one year as he
returned to Cambridge where he had been chosen to be the first
Lucasian Professor of Mathematics, a chair newly founded by Henry

ISAAC NEWTON

Lucas. It is the second oldest of the non-royal foundations and one
of the most illustrious chairs of science in the world; besides the first
two, Barrow and Newton, its roll includes such eminent mathe¬
matical physicists as Whiston, Airy, Babbage, Stokes, and its present
incumbent, Sir Joseph Larmor. Barrow resigned the professorship,
after six years, to Newton whom he frankly acknowledged to be his
superior and devoted the remainder of his life to theology. He was an
excellent Master of Trinity from 1672 until his early death in 1677.
He was noted for his strength, courage, and wit, and was a great
favourite of Charles II. Courtiers could not forgive him for being
slovenly in dress and an inveterate smoker. In appearance he was
small, lean, and pale. 22

Our knowledge of Newton’s other collegiate work is not so full
and, fortunately, it is not so important. We have to depend on our
general information as to the subjects considered most valuable in
the seventeenth century, and on casual hints made by Newton.

He certainly had a thorough grounding in Latin. 23 He would
read the standard authors in that language and would listen to exposi¬
tions and criticisms on their meaning and style. Much time would be
given to grammar and composition. But, in addition to the classical
literature, the student of the day would learn mediaeval Latin as a liv¬
ing tongue as most works of importance were written in it and it
formed a common medium of speech between scholars of different
countries. It was, indeed, a most convenient, flexible, and universal
form of communication; and one of the most unfortunate barriers to
the interchange of scholarly work was raised when the growing influ¬
ence of nationalism induced humanists and scientists to write, each
in his native tongue. The burden, today, of learning indifferently
well half a dozen languages as tools of scholarship has been discov¬
ered too late. An international language has been lost, and we turn a

- 2 His most important scientific works were, a complete edition of Euclid, 1660; Lectiones
mathematicae, delivered 1664— 6 , and published 1683; Lectiones opticae et geometricae , 1669.
Barrow was also a great master of English and his Sermons rank with the best in the
language.

23 Hearne several times in his Diaries affirms that Newton “does not understand a bit of
classical learning . . . nor can he, as I hear, write Latin.” But Hearne was rabidly anti-
Newton, both as an Oxonian and as an advocate of Hooke. He also in his Diaries, accuses
Newton of not being able to keep his accounts at the Mint, of being a parodoxical chronolo-
gist, of having stolen Hooke’s ideas on gravitation, etc. Cf. Hearne’s Diaries, London, 1869,
vol. II, pp. 216, 245, 277, 309, 310.—But Newton’s library contained most of the Latin
classics and an extraordinary collection of the Church Fathers. As most of the Greek authors
were in editions giving a Latin translation it is probable that his knowledge of Greek was
not thorough. Much of his correspondence is in fluent Latin and I found only one document
where the language was defective; Conduitt states that he could converse in it.

CAMBRIDGE UNIVERSITY

deaf ear to the cacophonous inventions of modern enthusiasts who try
to create new ones:

“Per lo cui mal coto

pure un linguaggio nel mondo non s’usa.”

Newton also learned Greek but probably not so thoroughly, as inter¬
est in it had declined. He, apparently, if we can trust one of his
note-books, learned the Hebrew alphabet and may have been able to
puzzle out portions of the Old Testament in the original. Of Ger¬
man he knew nothing and he confessed, in a letter to Collins, that
he was so deficient in French that the gift of a book in that language
would be useless.

Both classical and Biblical history was much cultivated and care¬
fully taught, as it was the common belief that all the examples of
character and manners were better illustrated in ancient than in
modern times. There was, I think, in Newton’s day not one univer¬
sity professorship of modern history, as the lectureship founded by
Fulke Greville had lapsed, and the students depended on their tutors
for such current historical facts as were thought worth emphasising.
Much attention was paid to logic and ethics, but in philosophy Cam¬
bridge still held fast to the mediaeval interpretation of Aristotle and
he would acquire little of the mechanistic philosophy of Descartes. .

The period of three years, 1664-1666, is the most crucial one in
Newton’s life; during it, his power of scientific invention was at
its highest and the foundation for all his future work was laid. He
seems to have suffered from an illness during the year 1664, brought
on, as he thought, by excessive work and the late hours he kept
while observing the comet of that year. He also observed and noted
a double halo about the moon. 24 From this illness, he is reported to
have learned to keep early hours; but “early hours” must be
thought of as an elastic term, for he certainly kept to no regular
habits when he was engrossed in work. In the same year he was
elected a Scholar of Trinity College with forty-four others. It was, as
previously noted, at this examination that Barrow is reported to have
found him deficient in Euclid.

In addition to the above facts of that year, it is stated in Conduitt’s

24 He afterwards referred to this phenomenon in his Optics (Bk. II, part IV, Obs. 13)
and gave a correct explanation of it. He noted that he had observed the haloes Feb. 19th,
1664, at dusk and having, in 1692, seen the same effect from a vase of stagnant water, he
assigned the cause to the light reflected from the moon’s surface, and then refracted from
drops of water in the air to the observer’s eyes.

4 o

ISAAC NEWTON

MSS. that Newton bought a prism at the Stourbridge Fair in August,
1665, to test Descartes’s theory of light and soon discovered that
author’s error and his own true theory; the authority for this state¬
ment is an item in an expense-book which has since been lost. 25

In January, 1664/5, three and a half years after his matricula¬
tion, Newton took his Bachelor of Arts degree with twenty-five other
Trinity men.‘ G It is unfortunate, Edleston notes, that the rank in
graduation of the most illustrious candidate from Trinity College for
a degree cannot be ascertained, as the Ordo Senioratatis, correspond¬
ing to the present Tripos list, of the Bachelor of Arts for the year
is provokingly omitted in the Grace Book. His pupillage was fin¬
ished; he had mastered his mathematical tools and his inventive
genius had awakened. A few months later he committed to writing
his first ideas on the method of fluxions, and occasionally placed dots
over his algebraic symbols to indicate an infinitesimal quantity.
While he probably did not attack at this time any original problems
by his new method, and although the subject may have been in the
air, yet it was an achievement of the greatest significance for a
youth of his age to advance beyond the work of the veteran Wallis.
He had, in effect, discovered a new and powerful mathematical
method, which lay concealed in Wallis’s work, worthy of a new and
distinct form of notation. Judging from items in an expense-book
given below, he relaxed somewhat the austere discipline of his life
and joined in some of the festivities incident to graduation; at least he
was at the tavern several times and twice lost money at cards. He
had passed more than three years in hard study under the direction
of others; his mind was filled with new ideas and for one of his
temperament there was need for leisure, a time when he could
arrange and digest his thoughts.

This golden opportunity came to him in the autumn of this year
when the great plague 27 closed the University and forced him to live
in seclusion at Woolsthorpe for the larger part of two years. There

-^According to Edleston (Cf. infra) he left Cambridge before August and if so could
not have attended the Fair.

2G Apparently there was a rumour that Newton did not distinguish himself in his exam¬
inations. I found the following anecdote in a letter written by Stukeley to Dr. Mead: “I
heard it as a tradition when I was student at Cambridge that when Sir Isaac stood for his
bachelor of arts degree he was put to second posing, or lost his greats, as they call it, which
is looked upon as disgraceful.” Cf. Portsmouth Collection.

The great bubonic plagues, known as the Black Death and so vividly described in
Manzoni s / promessi sposi, swept over Europe in the fourteenth century and are reported
to have killed one-fourth of the whole population. Successive outbreaks recurred in the
fifteenth and sixteenth centuries, but they grew less frequent and severe in the seven-

CAMBRIDGE UNIVERSITY

are discrepancies in the statements as to when he was in Woolsthorpe,
but the most reliable information has been given by Edleston who
made a thorough examination of the College records. 28 With some
slight chance of error, we can fix the absence of Newton from Cam¬
bridge and residence at home, omitting possible visits elsewhere,
as being from about August first, 1665, to Lady Day, March 25th,
1666; and from June 22nd, 1666 to probably March 25th, 1667. As
the plague decreased during the winter he may have been in Cam¬
bridge part of the period from March 25th to June 22nd, 1666; and as
he received only five weeks’ commons in the Lent Term of 1667, he
may have returned to the University at any time after the middle of
February, but it is likely that College did not reopen until the begin¬
ning of the Easter Term of that year.

There are no other examples of achievement in the history of
science to compare with that of Newton during those two golden
years. That a youth, who had shown no decided precocity of intellect
in his boyhood and who had followed his college course with no
more distinction or notice than have thousands of other collegians,
should immediately after graduation retire to a lonely village and
there, unaided, make three capital discoveries in science, is nothing
short of the miraculous. The first of these inventions was the mathe¬
matical method of fluxions, the basis of all modern mathematics and
the instrument by which all physical problems involving force and
motion are now solved. The second was the law of the composition
of light from which he later constructed a real science of optics. And
the third was the law of universal gravitation.

While the first and second led to great results, they do not stir the
imagination so deeply. But the conception of a universal force,

teenth century until the Great Plague of 1664-1665. Both Pepys and Defoe have given de¬
tailed and graphic pictures of its effects. Its onset was slow, until, in the summer of 1665,
it began to spread more rapidly and became so terrible that in London alone the mor¬
tality was above 31,000. The following winter it declined, but it reappeared the next
year in a less severe form.

28 The College was dismissed on August 8, 1665, at the breaking out of the plague as
shown by the Conclusion Boo\: “A month’s commons allowed to all Fellows and scholars
which now go into the country upon occasion of the pestilence..” But Newton’s name does
not appear in the list of those who received extra commons for six and one-half weeks on the
occasion, and Edleston concludes he must have left Cambridge before then. The students were
again dismissed on June 22, 1666, on the reappearance of the plague. The Fellows and
scholars were allowed compensation for their commons during their absence. Newton
received on this account:

y. 4 d. weekly, for 13 weeks in the quarter ending Mich 3 , 1666.

12 .Dec. 21,

5 .Lady Day, 1667

Edleston, p. xlii.

ISAAC NEWTON

as it slowly developed in his mind for a quarter of a century, and
finally produced his incomparable Principia, is a unique achievement.
Laplace, who disdained to praise other men, acknowledged that,
since there can be but one cosmos, so there can be discovered but
once its dominating law; and to Newton fate presented this gift.
All others must be satisfied either to have prepared the way or to have
extended his results; he must stand alone on the summit. To New¬
ton, and to very few other mortals, could the verse of Halley be
applied without arousing an inward sentiment of protest lest the
gods be brought lower to earth.

“Nec fas est propius mortali attingere Divos.”

Newton—when he was asked how his mind conceived and worked
out his ideas—modestly replied that if he had any genius not com¬
mon to other men it lay in the fact that when an idea first came to
him, he pondered over it incessantly until its final results became
apparent. One of the most puzzling traits of his character was his
seemingly total lack of desire to disclose to others the fruits of his
meditation. He never once acknowledged that he owed any obliga¬
tion to the world or to the University which had so generously sup¬
ported him. The consequences of fame, which brought with it the
probability of criticism, were so repugnant that he time and again
protested that he would abandon science or would, at least, with¬
hold his work from publication until after his death. It may be said,
without great exaggeration, that it was as difficult to force his mind
to divulge his ideas as it had been for him to create them.

Although the detailed discussion of the discoveries Newton made
during the two years he lived in Woolsthorpe will be postponed to
later chapters, yet they should be noticed briefly now in order to fix
their chronological order. During these two years he wrote five
short papers on his new application of infinite series to a general
method of solving the properties of curved lines and the areas in¬
cluded by them. 29 This method, which he later developed into what
he called fluxions, is now known as the differential and integral
calculus. 30 His first paper was written at Cambridge with the date,

29 These papers were written by him in a common-place book and are listed in the
youthful papers of Newton in the Catalogue of the Portsmouth Collection, pp. i and 2.

30 The Rev. Dr. Derham, who was acquainted with Newton for thirty years, stated that
Newton told him he had thoughts on fluxions when he was a Junior at College but was
stopped by the plague. They came back to him when he read Mercator’s Logarithmotechnia
and Wallis’s work.

CAMBRIDGE UNIVERSITY

May 20th, 1665; as the method depended on the summation of
infinitesimal arcs of curves, he adopted the distinguishing notation
of placing a dot over an algebraic symbol when it denoted such
an infinitesimal quantity. On November 13th of the same year he
finished a second paper at Woolsthorpe in which he solved problems
involving tangents to curves and radii of curvature. He also found
the area of one hyperbola, the first time it had ever been done, and
with boyish enthusiasm he carried the calculation to fifty-two signifi¬
cant figures. The following year he prepared three more papers, the
first probably in Cambridge, dated May 16th; the second in October;
and the third in November while at home. So far as we know, he did
not take anyone into his confidence; and while he is supposed to have
used fluxions when he was engaged on the Principia, he destroyed
all evidence of it by reworking the problems in the method of the
classic geometry. Some of his results were published years later
against his wish, and it was not until the end of the century that he
made any public statement regarding them.

His second great discovery lay in the field of optics. Newton,
as we have seen, had been interested in the Copernican theory and he
had also read Kepler’s treatise on light. We may be sure also that
Barrow had taught his pupils the results of Descartes’s important
work on lenses and the telescope. The problem of the telescope was
just such a one as would attract Newton; it involved both theoretical
geometry and practical applications and must have revived the
joys of his childish days when he was absorbed in constructing
mechanical toys. He had, as early as 1664, bought a prism and had
made some observations on the refraction of light. Now, while he
was away from Cambridge on account of the plague, he prepared
himself seriously to study the problem of lenses and the refracting
telescope.

In the astonishingly short period of three months, he practised the
exceedingly difficult operation of grinding lenses of surfaces other
than spherical; he began an elaborate series of experiments with a
prism to prove his capital discovery of the unequal refrangibility of
the colours of the spectrum which mixed together give us the sensa¬
tion of white light; he arrived at the correct deduction that lenses,
even if so ground as to correct spherical aberration, would still have
the defect of confusing the image by chromatic aberration, because
the various colours would be refracted to different foci. As this
seemed to involve an insuperable defect in telescopes using lenses, he

ISAAC NEWTON

left off his glass grinding and turned his attention to constructing
an instrument equipped with concave mirrors instead of lenses, since
chromatic aberration is not produced by reflected light. Such a
reflecting telescope, as it is called, had been proposed and its details
calculated by James Gregory of Scotland and by Cassegrain of
France. Gregory was the first inventor of the instrument 31 and had
commissioned Reeves and Cox, expert glass-grinders, to make for him
the necessary mirrors but, as he was then preparing to go abroad,
he neglected to attend to the matter and the telescope was never made.
Newton frankly acknowledged that he had read the account of the
Gregorian telescope and then explained why his own invention was
an improvement on Gregory’s and Cassegrain’s arrangements of mir¬
rors. He had hardly begun to construct a reflector before he was
again “forced from Cambridge [in June] by the intervening plague,
and it was more than two years before he proceeded further.” 32 We
get an interesting side-light on his habit of profound absorption when
spurred by the pressure of new ideas; “to quicken his faculties and fix
his attention, he confined himself to a small quantity of bread, dur¬
ing all the time, with a little sack and water, of which, without
any regulation, he took as he found a craving or failure of spirits.”

There is less uncertainty, although it too presents its problems,
in regard to Newton’s discovery of the law of gravitation. Conduitt
states in his Memoirs sent to Fontenelle: “In the year 1665, when he
retired to his own estate, on account of the plague, he first thought
of his system of gravity, which he hit upon by observing an apple
fall from a tree.” 33 The story of the falling apple, as the trifling
incident which first directed his thought to gravitation, is supported
by Voltaire who had the story directly from Catherine Barton, New¬
ton’s favourite niece who lived with him for many years. “Un jour,
en 1 ’annee 1666, Newton retire a la campagne, et voyant tomber des
fruits d’un arbre, a ce que m’a conte sa niece [Madame Conduitt], se
laissa aller a une meditation profonde sur la cause qui entraine ainsi
tous les corps vers une ligne qui, si elle etait prolongee, passerait a

31 Gregory described his reflecting telescope in his Optica Promota published in 1663.
He had no idea of chromatic aberration but praised his instrument on the grounds that it
would make telescopes shorter and less unwieldy than they had become.

32 Edleston, p., xxi.

33 “The apple tree is now remaining, 1727. [It later became weakened by age and was
blown down in a storm.] In 1666 Sir Isaac was here [Woolsthorpe], for in that year he
attended the Heralds visitation at Grantham, and entered three descents of his family,
styling himself ‘of Woolsthorpe, ^Tt, 23, Anno 1666..’ Whilst he was here probably his
half sister Hannah Smith was married to Mr. Pilkington.” Turnor, p. 160.

CAMBRIDGE UNIVERSITY

peu pres par le centre de la terre.” 34 We have definite evidence that
Newton was in Woolsdiorpe in the late summer and early autumn
of both these years, and this prime discovery was made in one of them.
Brew r ster decides on 1665 in agreement with Conduitt, and Edleston
follows Voltaire in placing 1666 as the date. Apparently, at this
time, he made a rough calculation and satisfied himself that such a
force would account for Kepler’s laws of planetary motion. But,
so far as we can learn, he dropped the subject and we hear nothing
more about it for many years. The probable reason is that he im¬
mersed himself in his work on light. Judging however from his
habit, the law of gravitation was frequently a part of his meditation.

Newton returned to Cambridge early in 1667 and it is probable that
the University opened, the virulence of the plague having subsided,
on Lady Day, March 25th, as that day marked the beginning of the
Easter Term. On October first he was elected a Minor Fellow. 35
There were nine fellowships vacant that year, as no elections had been
held in 1665 and 1666. One of them was made by the death of the
poet, Cowley; two of the other vacancies were caused by Fellows
falling down staircases—whether the result of defects in the stairs
or of excessive conviviality may be left to the imagination. It is not
probable that Barrow was one of the examiners as he was only
thirteenth in the order of seniority of Fellows, and the first eight
only usually examined for so important an occasion. One of the
Senior Fellows was absent and another, Barton, had been ejected from
college in the preceding June on the ground of insanity; even so Bar-
row only became temporarily the eleventh in order. A description of
the examinations of the period is given in a memorandum by a
student about twenty-five years later: “The fellowes on the 3 d day of
their sitting must have a theme given them by the Master, w h the
chappel-clerk fetcheth for them: they sit 3 dayes being excused the
4th for their theme. They sit from 7 till 10, & from one to 4, each writ¬
ing his name his age & his country; as doe the scholars, & also y e Mas-

34 Voltaire, Elemens de philosophic de Newton, Pt. Ill, Ch. III.

35 “The statutes only prescribe, that the persons chosen must be under the standing of
Master of Arts. From the date of the statutes, 1560, to the year 1667, the Fellows were
chosen promiscuously from the three years of Bachelors: but it is to be observed, that
although the elections were sometimes held annually, they were more commonly biennial,
or triennial. It was in 1667, the year made forever memorable in College annals, by the
admission of Sir Isaac Newton to a fellowship, that the candidates were first confined to
the third year of Bachelors. This continued the practice in all subsequent years, with two
or three exceptions, till 1752.” After that date Middle Bachelors were admitted to the com¬
petition; since 1819, Junior Bachelors have been permitted to be candidates. Monk’s
Bentley, Vol. II, p. 248.

ISAAC NEWTON

ters of Arts, w ch papers are carried to y e Master & Vice-M r , the first
morning so soon as all have written .. . Octob. I ... by y e tolling of
y e little bell at 8 in y e morning y e seniours are called & the day after
at one o’clock to swear them y 1 are chosen.” 36

As was the custom in Trinity College, rooms were assigned to
the new Fellows in the order of their seniority as soon as any fell
vacant; the room so assigned to a person was called his “seniority”
or “fellowship chamber.” In the schedule for September 30, 1667,
bearing the signature of John Pearson, the Master, the last line runs:
“to S r Newton—Spirituall chamber.” Edleston has been unable to
find what room was so designated, but he conjectured that “it was
the ground-floor apartment next the Chapel, at the north-east
corner of the great Court.” Although this was officially the room
assigned to him, it is quite possible that he did not occupy it, as the
Fellows had the privilege of sub-letting and receiving the rent. 37

A few months later, on March 16, 1668, Newton was admitted as
Major Fellow; and on July 7 of the same year, he was created Master
of Arts, the twenty-third on the list of 148 signed by the Senior Proc¬
tor, Thomas Burnet, author of Theoria Telluris Sacra™ When he
resigned his fellowship, shortly before December 21, 1701, he had
risen to tenth on the list and, if he had held the fellowship for
about two years longer, he would have succeeded to one of the eight
senior fellowships. 39

Thus, in seven or eight years, Newton had risen from exigent cir¬
cumstances and the menial rank of a Sizar to affluence and the
coveted position of Fellow of Trinity College, to be followed in a year
by the Lucasian professorship of mathematics, one of the highest
honours in the scientific world. Brewster echoes the old cry of the
disgrace to the nation, that such a man was permitted to remain in
the poverty and obscurity of a university position for so many years.
There have been many cases where eminent men have been worried
by poverty and lack of appreciation, but he fortunately escaped such
a fate. In the first place, the rank and esteem of one engaged in the
scholarly life are not, nor should they be, estimated by financial re¬
wards; and in the second place, he was from now on in the perma¬
nent possession of a comfortable income with the freedom from all
those harassing demands on his time which are the lot of those in
commercial or public service; he had won the precious leisure to
occupy himself fully in his meditations and scholarly work; and to

86 Edleston, Preface, p. xlii. 87 Ibid., p. xliii. 88 Ibid., p. xliv. 89 Ibid., p. lxxxii.

CAMBRIDGE UNIVERSITY

the end of his long life he enjoyed a respect and an admiration which
have rarely been accorded to any human being.

No one should picture Newton as a typically abstracted scholar.
He was scrupulously exact and regular in his business matters. He
kept detailed and minute accounts of his expenses and his receipts;
as an instance, he was only twice in arrears of the steward’s bills.
Though he was remarkably generous in gifts and loans, especially to
his family, he steadily increased his fortune until he died a very
rich man. While he was at the University he enjoyed excellent
lodgings and board. From his fellowship, he received his share of the
annual dividends accruing from the income of the College, his share
of the pandoxator’s dividend which came from the receipts of the
College bake-house and brew-house, his allowance “pro pane et potu”
of 3 s. 4 d. weekly during residence, and his livery allowance of £2 a
year. In addition to the above, he had about £ 100 a year from his
professorship, and ^80 from his estates. 40 De Morgan estimated his
income from all sources to have been not less than £250, over and
above his board and lodging. 41

While it may be difficult and misleading to translate the living
value of an income at that time into terms of modern conditions,
we can obtain a pretty fair knowledge of living expenses from con¬
temporaneous diaries and letters. For example, a note in Pepys’s
Diary tells us that Phineas Pett, Clerk of the Cheque, a good position
in the civil service of the navy, had a salary of £ 120. 42 Pepys refers
to his own expenses, in 1662, “I End that I had spent above £250 this
last half year.” 43 Now the genial diarist lived well in a good house in
London where he supported a wife and servants. Yet in spite of his
complaint of extravagance, he had spent only at the rate of twice
Newton’s income. A century later, Dr. Johnson lived comfortably,
maintaining a house and several inmates, on a pension of ^300. The
most significant statement I have found to support my opinion is a
letter of David Hume written in 1751 in which he said: “I have
^50 a year, a ^100 worth of books, great store of linens and fine
clothes, and near X 100 m m Y pocket; along with order, frugality, a
strong spirit of independence, good health, a contented humour, and
an unabating love of study. In these circumstances I must esteem

40 Edleston, Preface, pp. lxxxii-lxxxiv.

41 De Morgan, Essays, p. 43. My estimate agrees with that figure. Col. de Villamil has
recently in his Newton: the Man made an elaborate study of Newton’s income which he
places at jT 200*

42 Pepys’s Diary, Vol. I, p. 6 4. 43 Ibid., Vol. I, p. 261.,

4 8

ISAAC NEWTON

myself one of the happy and fortunate.” 44 This evidence seems con¬
clusive that Newton’s income of at least £200, with board and
lodging, was amply sufficient for a bachelor living in Cambridge,
unless he had to use a considerable portion of it to support his rela¬
tives. This opinion is strengthened by the fact that the year after his
fellowship was continued in 1676, and without any known addition
to his income, he contributed £/\o to the fund for building the Li¬
brary, a sum in excess of his income from the fellowship.

It is probable that while Newton was in Woolsthorpe, or shortly
after his return to Cambridge, the engagement with Miss Storey was
broken off, or what is more likely, faded away. If he had married,
it would have been necessary for him to renounce his university
career; by this time he must have foreseen the bent of his mind
and that a brilliant career was before him. A fellowship was imme¬
diately in sight; and Barrow, who had discovered his mathematical
genius, may already have intimated his approaching retirement from
the Lucasian professorship and his decision to recommend him as a
successor. Certainly, there was no distressing rupture; Miss Storey
remained his life-long friend; he aided her with money and gifts and,
in her old age, she fondly recalled the incidents connected with
her youthful lover.

With leisure and freedom from the routine of college lessons,
Newton greatly extended his reading and his interests. We learn
from his expense book and other sources, that he bought the
History of the Royal Society, the Philosophical Intelligences, Gun¬
ter’s Boo\ and Sector for Surveying, Bacon’s Miscellany, materials
and apparatus for lenses, for the study of electricity and magnetism,
and for chemistry. He took occasional trips to London and elsewhere,
and engaged in a mild sort of social life.

We fortunately have preserved for us one of the few personal
letters of Newton which I shall quote in full in spite of its length.
In most of his correspondence he confined himself to the discussion
of scientific or impersonal questions, and rarely alluded to his private
affairs. 45

44 Burton’s Life of Hume, Vol. I, p. 342.

4j This letter was addressed to his college friend, Francis Aston, who was about to start
on a foreign tour, and is printed in Macclesfield’s Collection, Vol. II, p. 292.—Aston after¬
wards, became. Secretary of the Royal Society in 1678, and his manner of resigning that
office in 1686 indicates that he did not profit from the cautious counsels of his friend. His
successor Halley wrote to a friend: “On St. Andrew’s day last, being our anniversary day
of election, Mr. Pepys was continued President, Mr. Aston, Secretary, and Dr. Tancred
Robinson chosen in the room of Mr. Musgrave; everybody seemed satisfied, and no dis-

CAMBRIDGE UNIVERSITY

Newton to Aston

p r Trin. Coll. Cambr. May 18, 1669.

Since in your letter you give me so much liberty of spending my
judgement about what may be to your advantage in travelling, I shall
do it more freely than perhaps would otherwise have been decent.
First, therefore, I will lay down some general rules, most of which
I believe you have considered already; but if any of them be new to
you, they may excuse the rest; if none at all, yet it is my punishment
more in writing them than yours in reading them.

When you come into any fresh company, 1. Observe their hu¬
mours. 2. Suit your own carriage thereto, by which insinuation you
will make their converse more free and open. 3. Let your discourse
be more in queries and doubtings than peremptory assertions or dis-
putings, it being the design of travellers to learn, not teach; besides, it
will persuade your acquaintance that you have the greater esteem of
them, and so make them more ready to communicate what they know
to you; whereas nothing sooner occasions disrespect and quarrels than
peremptoriness. You will find little or no advantage in seeming
wiser or much more ignorant than your company.

4. Seldom discommend any thing, though never so bad, or do
it but moderately, lest you be unexpectedly forced to an unhandsome
retraction. ’Tis safer to commend any thing more than it deserves,
than to discommend any thing so much as it deserves. For com¬
mendations meet not so often with oppositions, or at least are not
usually so ill resented by men that think otherwise, as discommenda¬
tions. And you will insinuate into men’s favour by nothing sooner
than seeming to approve and commend what they like; but beware
of doing it by a comparison.

5. If you be affronted, ’tis better in a foreign country to pass it
by in silence, or with a jest, though with some dishonour, than to
endeavour revenge: for in the first case, your credit is ne’er the

content appear’d anywhere, when on a sudden Mr. Aston, as I suppose willing to gain
better terms of reward from the Society than formerly, on December 9th, in Council,
declared that he would not serve them as Secretary; and therefore desired them to pro¬
vide some other to supply that office; and that after such a passionate manner, that I fear
he has lost several of his friends by it.” Weld, Hist. Roy. Soc., Vol. I, p. 303. In spite
of the outbreak, the Council made him a gratuity of £ 60. Shortly afterwards Newton wrote
to him that he and Mr. Charles Montague had failed to establish a philosophical society at
Cambridge. Aston communicated a paper to the Royal Society which was published in
1692. At his death, he bequeathed an estate in Lincolnshire, to the Royal Society, still in
its possession, and personal property to the value of £445. Weld, Vol. I, p. 428.

ISAAC NEWTON

worse when you return into England, or come into other company
that have not heard of the quarrel; but in the second case, you may
bear the marks of your quarrel while you live, if you outlive it at all.
But if you find yourself unavoidably engaged, ’tis best, I think, if you
can command your passion and language, to keep them pretty evenly
at some certain moderate pitch, not much heightening them, to exas¬
perate your adversary or provoke his friends, nor letting them grow
overmuch dejected to make him insult. In a word, if you can keep
reason above passion, that and watchfulness will be your best defend¬
ants. To which purpose you may consider, that though such excuses
as this,—He provoked me so much I could not forbear,—may pass
amongst friends, yet amongst strangers they are insignificant, and
only argue a traveller’s weakness.

To these I may add some general heads for enquiries or obser¬
vations, such as at present I can think on. As, i. To observe the
policies, wealth, and state affairs of nations, so far as a solitary traveller
may conveniently do: 2. Their impositions upon all sorts of people,
trades, or commodities, that are remarkable: 3. Their laws and
customs, how far they differ from ours: 4. Their trades and arts,
wherein they excel or come short of us in England: 5. Such fortifica¬
tions as you shall meet with, their fashion, strength, and advantages
for defense, and other such military affairs as are considerable: 6. The
power and respect belonging to their degrees of nobility or magis¬
tracy. 7. It will not be time misspent to make a catalogue of the
names and excellencies of those men that are most wise, learned,
and esteemed in any nation. 8. Observe the mechanism and manner
of guiding ships. 9. Observe the products of nature in several places,
especially in mines, with the circumstances of mining and of extract¬
ing metals or minerals out of their ore and refining them; and, if
you meet with any transmutations out of one species into another,
(as out of iron into copper, out of any metal into quicksilver, out of
one salt into another, or into an insipid body, etc.,) those above all
others will be worth your noting, being the most luciferous, and
many times lucriferous experiments 46 too in philosophy: 10. The
prices of diet and other things: 11. And the staple commodities of
places.

These generals, (such as at present I could think of,) if they
will serve for nothing else, yet they may assist you in drawing up a
model to regulate your travels by.

46 This is one of the stock phrases of the alchemists to distinguish those experiments
which advanced knowledge from those which added to the income.

CAMBRIDGE UNIVERSITY

As for particulars, these that follow are all that I can now think
of, viz, Whether at Schemnitium in Hungary (where there are mines
of gold, copper, iron, vitriol, antimony, etc.,) they change iron into
copper by dissolving it in a vitriolate water, which they find in cavi¬
ties of rocks in the mines, and then melting the slimy solution in a
strong fire, which, in the cooling, proves copper. The like is said
to be done in other places which I cannot now remember. Perhaps
too it may be done in Italy; for about twenty or thirty years ago
there was a certain vitriol came from thence, (called Roman vitriol,)
but of a nobler virtue than that which is now called by that name,
which vitriol is not now to be gotten, because, perhaps, they make
a greater gain by some such trick as turning iron into copper with it,
than by selling it. 2. Whether in Hungary, Sclavonia, Bohemia, near
the town Eila, or at the mountains of Bohemia near Silesia, there be
rivers whose waters are impregnated with gold; perhaps the gold
being dissolved by some corrosive waters like aqua regis, and the
solution carried along with the stream that runs through the mines.
And whether the practice of laying mercury in the rivers till it be
tinged with gold, and then straining the mercury through leather,
that the gold may stay behind, be a secret yet, or openly practised.
3. There is newly contrived, in Holland, a mill to grind glasses plane
withal, and I think polishing them too; perhaps it will be worth your
while to see it. 4. There is in Holland one—Bory, who some years
since was imprisoned by the Pope, to have extorted from him some
secrets (as I am told) of great worth, both as to medicine and profit,
but he escaped into Holland, where they have granted him a guard.
I think he usually goes clothed in green: pray enquire what you can
of him, and whether his ingenuity be any profit to the Dutch. 5. You
may inform yourself whether the Dutch have any tricks to keep their
ships from being all worm-eaten in their voyages to the Indies.
Whether pendulum clocks be of any service in finding out the longi¬
tude, etc.

I am very weary, and shall not stay to part with a long compliment,
only I wish you a good journey, and God be with you.

Is. Newton.

P. S. Pray let us hear from you in your travels. I have given your
two books to Dr. Arrowsmith. 47

47 Brewster finds this letter a difficult matter to reconcile with his policy of presenting
facts accurately and, at the same time of depicting Newton’s character as the exemplar of
all the virtues. He comments (see Vol.. I, p. 34) on the author’s advice in the following dry
and cautious manner: “This ‘letter’ is a very interesting production. It does not evince much

ISAAC NEWTON

If this famous letter had not been taken too seriously and often
quoted as an early example of Newton’s wise and noble character,
there would be little need to comment upon it. Newton, like Wash¬
ington, has been portrayed as a man with none of the ingenuousness
or exuberance of youth. Should we not rather picture to ourselves two
young men discussing the great event of a first trip abroad? The
surprising thing is, that Aston should have looked to Newton for
counsel and that he, in turn, should have considered himself capable
of giving advice. Perhaps, also, the letter was a youthful bit of hu¬
mour, disguised by ponderous seriousness, and I should like to think
that Newton could occasionally unbend. If we take the letter seri¬
ously, Aston might have complained that he received little more than
the standard seventeenth century “advice to travellers making the
grand tour.” But he would scarcely expect much valuable advice
from a youth of twenty-four who had seen no more of the world
than was comprised in his home and adjacent counties. He received
the effusion of a young man assuming the pose of the worldly wise. I
can thus agree neither with Brewster nor with De Morgan as the in¬
dividualising parts of the letter throw but little light on Newton’s
own character, but they do reflect his interests.

The list of general things to be observed is such as any enquiring
person might choose. But Newton picks out particularly two subjects,
glass-work and chemistry, that he is interested in himself. There can
be no doubt that chemistry was engrossing his mind or that he was
a credulous alchemist. His naive enquiries about the processes of
changing iron into copper and of the charlatan, “one Bory, clothed
in green,” are indications of wide but desultory reading. So, too,
they give us a glimpse of his youthful ambition to devote himself to
luciferous experiments, and of his dreams of turning such knowledge
into the lucriferous creation of gold. It was with great reluctance and
after long years of labour that he finally became sceptical of the
pretensions of alchemy.

Reference was made in the previous chapter to two note-books
preserved by Newton which give an interesting account of his activi-

acquaintance with the ways of the world, but it shows some knowledge of the human
heart, and throws a strong light on the character and opinions of its author.” One wonders
what light Brewster really thought it to be. Having asked a friend to read it, I was
surprised by his opinion that Newton was writing either cynically or humorously. De
Morgan, on the other hand, cites the advice on how to behave when insulted by foreigners
as typical of Newton’s grave defect of character such that “he had not within himself
the source from whence to inculcate high and true motives of action upon others; the fear
of man was before his eyes.” Essays, pp. 132-134.

CAMBRIDGE UNIVERSITY

ties and expenses at this time. Sufficient abstracts were given of the
items referring to his Grantham days. As he continued the entries for
several years after he went to College I have taken some of the items
when he first went up to Cambridge as they give a vivid glimpse of a
student’s expenses.

IMPENSA PROPRIA

£ s d

Sewsterne . o—i—o

Stilton . o—2—o

Cambridge White Lion . o—2—6

Carriage to the College. o—o—8

A chamber pot. o—2—2

A table to set down the number of my clothes

in the wash. o—i—o

A paper book. o—o—8

For a quart bottle and ink to fill it. o—i—7

Income for a glass and other things to my
Chamberfellow . 0—0—9

0—12—4

He also seems to have had the habit of lending money to his school¬
fellows; there are ten or more such entries and I suspect that he eked
out his scanty income by charging for the accommodation. 48

48 As his list of expenses is valuble in giving an idea of his social life and of his work, I
experienced a more personal contact with Newton when reading his little book than from
any of his other papers in the Portsmouth Collection. The abstract which follows is also
to be found in Brewster, Vol. I, p. 32.

1665

Received, May 23d, whereof I gave my tutor 5s.,,. £ 5 0 0

Remaining in my hands since last quarter,. £ 3 g 4

In all,. £ 8 8 4

many loans. The following are among the entries:

Drills, gravers, a hone, a hammer, and a mandril, £ 0 5 o

A magnet, 0 t 6 0

Compasses, 0*6

Glass bubbles, 040

My Bachelor’s account, 0 X y ^

At the tavern several other times, 100

ISAAC NEWTON

Probably with the approval of Barrow, and possibly with his advice,
Newton undertook to expand his notes on his new calculus of fluxions
into a connected essay, with the title of On Analysis by equations with
an infinite number of terms. He then gave it to Barrow with the
permission to send it to that scientific intermediary John Collins, but
with his usual caution he stipulated that the name of the author was
to be kept anonymous. In a letter, dated 20th June, 1669, Barrow
merely announced to Collins that a friend staying at Cambridge had
written an important mathematical paper. In his next letter, he for¬
warded the manuscript with the hope that it would delight him.
Collins evidently expressed his warm approval, for Barrow then
wrote a third letter on the 20th August and, having overcome the
reluctance of the author, added that “the name of the author is New¬
ton, a Fellow of our College, and a young man, who is only in his
second year since he took the degree of Master of Arts, and who, with

Spent on my cousin Ayscough,

On other acquaintance,

Cloth, 2 yards, and buckles for a vest,

Philosophical Intelligences,

The Hist, of the Royal Society,

Gunter’s Book and Sector to Dr. Fox,

Lost at cards twice,

At the tavern twice,

I went into the country, Dec. 4, 1667.

I returned to Cambridge, Feb. 12, 1667.

Received of my mother,

My journey,

For my degree to the College,

To the proctor,

To three prisms,

Four ounces of putty,

Lent to Dr. Wickins,

Bacon’s Miscellanies,

Expenses caused by my degree,

A Bible binding,

For oranges for my sister,

Spent on my journey to London, and 4s or 5s more which my mother
gave me in the country,

I went to London, Wednesday, August 5th, and returned to Cambridge on
Monday, September 28, 1668.

Lent Dr. Wickins,

0 12

o 10

2 o

o 9

o 7

o 5

o 15

o 3

30 o

o 7

5 10

2 o

3 0

o 1

1 7

0 1

o 15

0 3

o 4

5 10

o 11

April 1669

For glasses in Cambridge.

For glasses in London.

For aquafortis, sublimate, oyle pink, fine silver, antimony, vinegar, spirit of

wine, white lead, salt of tartar, 2

A furnace, o

Air furnace, 0

Theatrum chemicum, 1

Lent Wardwell 3s., and his wife 2s., o

CAMBRIDGE UNIVERSITY 55

an unparalleled genius, has made very great progress in this branch
of mathematics .” 49

Barrow, who had the wish to return to his theological studies, had
now found one superior to himself; he resigned his professorship and
secured his successor in Newton at the early age of twenty-seven years.

49 Brewster, Vol. I, p„ 35.

CHAPTER III

LUCASIAN PROFESSOR. LECTURES ON OPTICS. INVEN¬
TION OF REFLECTING TELESCOPE. HIS NEW

THEORY OF LIGHT
1669-1673

U pon his appointment to the Lucasian Professorship, Newton
flung himself into the intense creative work which was to
absorb him for a score of years and raise him to a preeminent
position in science. Assured of a competent income and of a com¬
manding position in the University, he was free to follow his own in¬
clinations and to develop his ideas. The prescribed duties of his pro¬
fessorship were light as they required him to give only one lecture a
week during the Michaelmas term and two conferences a week with
students while he was in residence. He had also the choice of any
subject in the broad fields of mathematics and natural philosophy.
His professorial obligations were even less burdensome as he usually
had but very few auditors, and often none, at his lectures and hardly
any conferences with students.

Any one of three topics might have attracted the young professor’s
interest. He had been thoroughly grounded in classical geometry by
Barrow, and he had mastered by himself the new analytical geometry
of Descartes and Wallis which had been developed as a means of
solving the dynamical problems resulting from the discoveries of
Galileo. His work, during his retirement at Woolsthorpe, had pre¬
pared him to create a systematic calculus fitted to deal with all prob¬
lems of continuous motion. As a mathematician he was sui generis
since he seemed to grasp the solution of a problem immediately and
to have seen new methods of attack when the occasion demanded.
But, as an end in itself, he considered mathematics to be a dry and
barren subject; he valued it only as a tool and a language for the ex¬
pression of natural law. Thus, while he made inventions of first-
rate importance, he made them for his own use; he rarely developed
them systematically and had no desire to publish them for the use of

LUCASIAN PROFESSOR

others. He seems, also, to have believed that the modern analytical
methods, including his own, lacked the elegance and clarity which
are the peculiar glory of the classical geometry.

Newton was also prepared to lecture on astronomy and mechanics.
He had been deeply interested in the cosmical ideas of Copernicus,
Kepler, and Galileo, which had been expanded into a universal
mechanical system by Descartes. But he never attempted any as¬
tronomical observations and he was in his youth too near-sighted to
make them efficiently. While he was convinced that he had found
the long sought cosmical force of attraction it required the medita¬
tions of twenty years to prepare him to establish the universal law of
attraction and work out its applications to natural philosophy. So
the discovery remained in his mind as a more or less isolated problem
which he jealously guarded till its general solution in the Principia
became the crowning achievement of his life.

In spite of the attraction those subjects had, Newton chose optics
for his maiden effort, and continued his lectures on light during the
next two years. This branch of physics, following the discovery of
the telescope, was a field of great activity and his choice was a wise
one. He had made the fundamental discovery of the composite
nature of white light which he thought disclosed an ineradicable
defect in the refracting telescope. He had studied the geometrical
properties of lenses; he had practised the art of grinding and polish¬
ing glass; and he had constructed a telescope which he thought
avoided the faults of the type in use. Here, then, was a subject which
combined skillful handicraft with the rigour and elegance of geom¬
etry; one in which he had been so systematically trained by Barrow
that he was consulted during the preparation of his master’s Lectures
on Light for the press. That his topic was congenial to him is evident
from the fact that it is the only one which awakened in him a burst
of enthusiasm and pride when he disclosed his ideas to the world.
The lectures were “deposited, at the time they were read, amongst
the archives of the University: from whence many copies have been
taken, and handed about by the curious in these matters.” 1 The fact
that they had been thus circulated and garbled was a matter of in¬
tense annoyance to their author, which he many years later gave as
a reason for the publication of his treatise on Optics. The lectures
were published posthumously in 1729 2 from a copy given by Newton

1 Greenstreet, p. 70.

2 Lectiones Opticae, Annis MDCLX1X ad MDCLXXI, in Scholis Publicis habitae: et nunc
primam ex MSS. in Lucem editae, Londini.

ISAAC NEWTON

to David Gregory, Savilian Professor at Oxford. An English transla¬
tion, of the first part only, had been printed the year before with a
preface by the anonymous translator. They are also included in
Horsley’s Opera Omnia.

In order to make clear the current knowledge of the phenomena
and laws of light when Newton began his own investigations, we
may conveniently glance at Kepler’s Parahpomena ad Vitellionem
which was published in 1604. While this treatise on light has all the
verbosity and discursiveness so characteristic of the author’s style and
thought, we may be certain that he includes all that other men knew
about the subject and adds new material of his own.

Kepler accepts the current idea that the velocity of light is infinite
because the medium of its transference offers no resistance of friction.
With the exception of a trial proposed by Galileo by noting the time
of lantern signals passed from one observer to another, a method quite
inadequate, no one had even attempted to measure its velocity. It
was not until 1675 that Roemer used the indirect method of noting
the variations in time between the observed and calculated eclipses of
the moons of Jupiter at different positions of the earth’s orbit and so
obtained a fair approximation of the enormous speed of light.

The laws of reflection are stated accurately by Kepler, but the laws
of refraction were not known, and he merely affirmed that its angle,
when light passes from a rarer into a denser medium, increases less
rapidly than the angle of incidence. By actual trial he worked out
many practical problems for finding images in plane and spherical
mirrors, and in lenses, but he could give no general formulas for the
positions of objects and images. When, in 1609, the invention of the
telescope was brought to his attention, he quite erroneously claimed
that it had been suggested by a diagram in this book of a concave and
a convex lens accidentally drawn on the same axis. It was Kepler
who, by these investigations, proved that a plano-convex lens brings
rays, that are parallel to its axis, to a focus at a distance equal to the
diameter of its curvature, and that the focal length of a double con¬
vex lens is just half that distance. But he did not investigate any rule
for the foci of lenses unequally convex.

When we turn to the section dealing with the nature and causes
of light and colour we find Kepler’s ideas are purely speculative and
quite typically obscure. In Proposition XV he states: “Colour is
potential light buried in pellucid matter (if it may be considered as
something independent apart from vision); and different properties

LUCASIAN PROFESSOR

in the nature of matter, because of rarity and density or of trans¬
parency and opacity, cause variety of colours. For since colours,
which are observed in the rainbow, are of the same nature as colours
in bodies, there must be the same cause of both. And indeed they all
occur at the boundary of light and shadow, as it is certain that they
owe their existence to the attenuation of light and a superinjection of
watery material. There is only this difference, light is adventitious
in the rainbow, and truly implanted in coloured bodies. Black is the
limit of all colours and is related to colour as a point is to a line; that
is, it pertains to a quantity although it is not a quantity.” If this
definition means anything, it is that colour is in some way a mixture
of light and darkness, modified by the specific properties of the body
through which it passes.

A knowledge of the laws of light was naturally of great importance
to the astronomer; but it was the invention of the telescope, five
years after the publication of Kepler’s treatise, which first opened the
eyes of the world to the possibility of applying science to practical
uses. No more startling illustration of the slowness of communica¬
tion in the seventeenth century, the little general interest in science,
and the isolation of its scattered followers, could be given than the
fact that the foremost astronomer of the day did not learn of the in¬
vention of the telescope until nineteen years after it had been dis¬
covered and was in use in the neighbouring country of Holland. Per¬
haps even more extraordinary is the possibility, although the evidence
is doubtful, that Roger Bacon had made and used both telescopes and
microscopes in the twelfth century and had acquainted John Der
and others of his friends with their construction. If this be true, all
knowledge of such instruments had completely vanished.

The credit for this marvellous aid to human vision apparently lies
between two Dutch spectacle-makers, Zacharias Joannides (Jansen)
and John Lippersheim, both of Middelburgh. The most circum¬
stantial and authentic account of the invention of the telescope is to
be found in the almost contemporaneous De vero telescopii inven-
tore of Borellus. He assigns the honour of the discovery to Jansen
who, in 1590, fortunately hit upon the combination of a double con¬
vex lens as an object glass and a double concave lens for an eye-piece.
There is a legend that one of his children, while playing with some
lenses, accidentally placed two of them in such a position as to make
a telescopic combination and called to his father to look how large
everything appeared. Whether the legend be true or not, it is cer-

ISAAC NEWTON

tain that it was not due to chance, as Jansen was a diligent enquirer
into nature and was trying to learn what uses could be made of
lenses, other than for spectacles. As soon as he discovered the tele¬
scopic effect of this combination of lenses, he enclosed them in a tube
and presented the instrument to Prince Maurice. As the Prince found
that the instrument would aid him in his wars to observe the actions
of the enemy, tire inventor was ordered to keep it a secret. Though
this was attempted for some time, the discovery leaked out and several
persons in the city applied themselves to the making and selling of
telescopes. Borellus also states that the son, John, observed the spots
on the moon and the face of Jupiter, and “sometimes he perceived
two, sometimes three, and at the most four small stars, a little above
or below him; but this, he says, he leaves to the consideration of
astronomers.”

If this account be true, it took nineteen years for the rumour of a
strange instrument which had been invented by a spectacle maker of
Holland to reach Galileo. In spite of its length, I shall give Priestley’s
vivid story of the incident.

“About April or May, in 1609, it was reported at Venice, where
Galileo (who was professor of mathematics in the university of
Padua) then happened to be, that a Dutchman had presented to
Count Maurice of Nassau, a certain optical instrument, by means of
which, distant objects appeared as if they were near; but no farther
account of the discovery had reached that place, though this was
near twenty years after the first discovery. Struck, however, with this
account, Galileo instantly returned to Padua, considering what kind
of an instrument this must be. The night following, the construc¬
tion occurred to him; and the day after, putting the parts of the in¬
strument together, as he had previously conceived of it, and not¬
withstanding the imperfection of the glasses that he could then
procure, the effect answered his expectations, as he presently ac¬
quainted his friends at Venice; to which place he, six days after¬
wards, carried another, and a better instrument that he had made,
and where, from several eminences, he shewed to some of the prin¬
cipal senators of that republic, a variety of distant objects, to their
very great astonishment. When he had made farther improvements
in the instrument, he, with his usual generosity, and frankness in
communicating his discoveries, made a present of one of them to the
Doge, Leonardo Donati, and, at the same time, to all the senate of
Venice, giving along with the instrument, a written paper, in which

LUCASIAN PROFESSOR

he explained the structure and wonderful uses that might be made of
it, both by land and at sea. In return for so noble an entertainment,
the republic, on the 25th of August, in the same year, more than
tripled his salary as professor.” 3

With characteristic energy, Galileo made more than a hundred of
these instruments with his own hands and turning them to the
heavens he revolutionised our knowledge of the solar system. In
March, 1610, he published an account of all his discoveries in his
N unci us Sidereus, dedicated to Cosimo, Grand Duke of Tuscany.
As a reward for this honour, the Duke invited him to quit Padua,
and assigned him a large salary as extraordinary professor at Pisa
with no obligations to lecture or to reside there. His astounding dis¬
coveries were the cause of speculation and debate among the philos¬
ophers and astronomers. Many were sceptical and some refused to
look through the tube lest it should shake their belief in Aristotle’s
philosophy. When the facts were settled beyond dispute, to save their
faces they claimed that the discovery was concealed in the philosophy
of their oracle. Galileo used to tell this story with his customary
humour by comparing such men to alchemists who imagined the art
of making gold was known to the ancients and lay hidden in the
fables of the poets. 4

It is an extraordinary fact that the Galilean telescope, which is the
familiar opera glass, remained the only known form for twenty
years. At best, it is an inferior instrument because the concave eye¬
piece diverges the light entering the eye and makes the field of view
exceedingly small. Combinations of convex lenses are far more ef¬
fective, since they converge the rays of light which enter the eye; and
it was by following the theoretical work of Kepler that other and bet¬
ter types of telescopes were constructed.

These new instruments aroused an intense interest in astronomy
and led to persistent study of the laws and grinding of lenses. The
essential difficulty to be overcome was inherent in all spherical glasses.
Rays of light refracted from portions near the rim of such a lens come
to a focus closer to it than the rays through the middle portion. This
fact, which is called spherical aberration, obviously blurs the image.
Descartes not only published the general laws of refraction, but also
devised a method for figuring and grinding aplanatic lenses having
surfaces, other than spherical, which would not produce spherical ab¬
erration. However, he did not mention any other type of telescope

3 Priestley, Vision, Light, and Colours, London, 1772, p. 60. 4 Priestley, p. 60.

ISAAC NEWTON

than the Galilean as having been actually constructed. Although
Kepler had suggested other possible combinations of lenses, the first
person who actually made a telescope with a combination of two or
three convex lenses was Father Scheiner, 5 about 1630. Since spherical
aberration decreases as the focal length of a convex lens is increased,
the desire for greater magnifying power and sharper images was met
by steadily enlarging the length of the instrument, till it was pro¬
posed to make one in France two hundred feet long. Such is the his¬
tory of this first practical and deliberate achievement of the new
scientific method based on observation.

I have very little sympathy with the distinction commonly made
between pure and applied science, or with the supposed superiority of
those who plead for “science for science’s sake.” The chief value of
science is that it increases our power over nature and adds to our
safety and comfort. Unless the possibility of practical applications to
the needs of society is very generally perceived, any branch of science
is certain to languish except for the unappreciated work of a few in¬
vestigators whose personal tastes lie in the field of abstract research.
Although astronomy may seem, at first sight, to be the most remote
of all the sciences from human problems, it is not difficult, however,
to show why it was the first to feel the quickening impulse of the
Renaissance.

In the first place, astronomy was the direct outgrowth of astrology
which, with the exception of alchemy, was the only science generally
cultivated during the Middle Ages because of its value to society.
From the most ancient times, the influence of the stars on life was
universally accepted as an established fact except by a few scoffers.
And the dominating influence of the heat and light from the sun on
physical and mental phenomena could be triumphantly pointed to
as an illustration of celestial power. Even more forcibly the mysteries
of the heavens touched the imagination and had been closely woven
into religion and philosophy. The future fate of every person was be¬
lieved to depend on the positions of the planets at the moment of
birth. The most elaborate and intricate rules for taking horoscopes
were devised and grave discussions were held in order to define what
was the exact moment of birth, in itself a rather protracted period of

5 The amusing story is told of Scheiner that he protested to his Provincial that he had
observed the spots on the sun before Galileo and the credit of the discovery had not been
given him. The answer was: Calm yourself, my son, I have read Aristotle through many
times and he nowhere mentions any spots. Change your glasses; the imperfections are in
them and not in celestial matter.

LUCASIAN PROFESSOR

time. One of the common expedients was to station an astrologer on
the roof of the house and to have the mid-wife notify him when the
infant uttered its first wail of protest. The foresighted person of
wealth and station maintained an astrologer in his household to ad¬
vise him whether the aspect of the stars was propitious before any
serious enterprise was undertaken. Medicines would not act prop¬
erly; the chemical elements would neither transmute nor combine;
beasts and plants would not propagate and grow satisfactorily, unless
the stars were benign in their aspect. In spite of the chicanery and
rascality which the astrologers practised in order to entice a liveli¬
hood from their ignorant patrons, there was also a genuine and en¬
thusiastic investigation of the planetary motions. Thus astrology
had a true scientific value and it needed only to be freed from its
mythological swaddling clothes to develop into astronomy. And as
astronomy advanced, the need for a greater knowledge of the sciences
of light and mechanics became imperative, since the one was neces¬
sary for locating stars and the other for calculating their motions.
These illustrations will, perhaps, serve to explain why astronomy
and, with it, the correlated subjects of optics and mechanics were the
fertile fields of science during the sixteenth and seventeenth centuries.
We may now return to a brief statement of the prevailing ideas on
the nature of light and colour.

Besides Kepler, I should mention Antonius de Dominis. In con¬
nection with his explanation of the cause of the rainbow, he gives in
his treatise De radiis visus, published by Bartolus in 1611, his ideas
on the nature of light. They are strictly Aristotelian. He explains
colour in this fashion: “If there be in a body pure light, as in the stars
or in fire, and it lose its brilliancy for any cause, it appears as white
light. If some darkness be mingled with the light, which yet per¬
mits it a passage and is not completely absorbed, there then occur
the intermediate colours. On that account our fire appears reddish
because it is mixed with smoke which darkens it. . . . There are
three intermediate colours. The least mixture of darkness which
dims the glitter of white light produces red. This may be shown by
passing sun-light through a three sided glass prism, the colour which
passes through the least thickness of the glass is red. Then follows
green which has passed a greater thickness of glass and so been more
absorbed and mixed with black. Finally, we observe blue which has
passed through the thickest part of the prism. If sun-light be still
more absorbed there occurs darkness, although this is a privation of

ISAAC NEWTON

light rather than a positive colour. 0 The important fact to be noted
is that the conception of “pure light, as in the stars or in fire” is iden¬
tical with Aristotle’s quintessence, his pure and incorruptible celestial
matter of the stars. In its passage through space this elemental fire
loses some of its brilliance and appears in its purest form as white
light. Aristotle, according to his habit of resolving into contraries,
then postulated darkness as an opposing entity. In the moral world,
light and darkness were confused with good and evil, and physically
they caused the sensations of whiteness and blackness; their mixture
was greyness. Colours also resulted from their combination when
light was affected by the action of the material substances through
which it passed.

It would be wearisome and useless to quote the opinions on the
nature of light of other contemporaneous writers. It was not until
Descartes made his deliberate attempt to overthrow the Aristotelian
science by portraying a universe which would involve only substance
and motion, that a new hypothesis of light and colour was advanced.
While his picture was purely fanciful, it had the result of directing
attention to what later became the mechanical wave theory of light.
The cause of light was attached to his theory of vortices in an in¬
genious way; and Descartes had the peculiar gift of using simple ex¬
amples, which gave an air of verisimilitude to even his most fantastic
ideas. He first accepted the Aristotelian idea of the impossibility of
a vacuum and placed each star and planet at the centre of a vast
vortex of cosmic matter whose motion in some way caused a drift of
matter towards the centre. Now the substance of the sun and stars
is celestial fire,—he was quite adept in using Aristotle’s ideas while
combating his philosophy. Although this celestial substance is con¬
stantly driven towards the centre of the vortex, yet, when it ap¬
proaches that point, it experiences a tendency to press out to the
equatorial surface because of its centrifugal motion. This conception
of matter as endowed with both a centripetal and a centrifugal ac¬
tion, acting in opposite directions, is only a revival of the mysterious
tonos of the Stoics. The effort, or tendency, to press out from the
centre constitutes light. With such an hypothesis, Descartes found
himself in a quandary when he later discussed the cause of colour
but, rather than confess ignorance, he assumed that this light pres¬
sure causes two kinds of motion, one circular and the other recti¬
linear, in “globules” of terrestrial matter. If the circular motion of

6 Chap. Ill, p. 9.

LUCASIAN PROFESSOR

the “globules” is the more rapid of the two we experience the sensa¬
tion of red when it agitates the retina; if it is the slower, the sensa¬
tion is blue; and if they are equal, it is yellow. All other colours are
compounded of these three primary sensations. As weird as this
speculation may be, it was changed by Pardies, a distinguished pro¬
fessor of Clermont College, Paris, and by Hooke of London into a
less fantastic scheme of vibratory motion; and later Huygens pro¬
posed a wave theory of light which in variously modified forms has
persisted to the present time.

Newton had evidently been deeply interested in the subject of
optics by his early study of Kepler and Descartes, and had mastered
all the facts and hypotheses then known. His boyish love for, and
skill in making, mechanical appliances had remained with him, and
at the beginning of the year after his graduation, March 25? 1660, he
devoted himself to the figuring and construction of lenses. Nothing
is more significant of the ardour and industry of the men of science
of that time than the labour and time spent by men like Galileo and
Newton in the actual construction of apparatus. Such labour is al¬
most incredible to us who have every facility of the expert apparatus
maker at our disposal.

The defect of the Galilean telescope, or opera glass, had become
only too evident. There was no method by which the field of vision
could be made large, and we may justly express our admiration at
the discoveries made with such an instrument. The future appar¬
ently lay with perfecting combinations of convex lenses. Such tele¬
scopes overcame the diverging defect of the concave eye-glass but
they introduced the fault of spherical aberration which the concave
eye-piece largely corrected. The great authority of Descartes led to
the attempt to make lenses whose surfaces were ground either to
parabolic or hyperbolic surfaces of revolution. It is a fairly easy mat¬
ter to make accurate plane and spherical surfaces since their curvature
is the same in all directions. The grinding tool can be held rigidly,
and the irregularities which are produced in one line of motion are
smoothed by the grinding along any other. The mechanical difficulty
for other surfaces is to combine a circular motion of the tool with a
simultaneous advance along the arc of a parabola or hyperbola so
slowly and accurately as not to leave minute ridges which scatter

the light.

Newton not only figured and ground lenses but he intimated to
Conduitt that he constructed his grinding and polishing machines.

ISAAC NEWTON

During this work he noticed an obscure effect which had escaped
the attention of his predecessors; he found that the images of tele¬
scopes and lenses were bordered with a coloured edge which blurred
their outline and made exact focusing even more difficult than did
spherical aberration. The failure of others to note this defect, now
called chromatic aberration, can be accounted for by the fact that
the concave eye-piece of the Galilean telescope partially compensates
the aberration of the object glass, and that the new type, with con¬
vex lenses only, was still in its infancy. But, one of the prime ele¬
ments of Newton s genius was that he rarely overlooked apparently
trifling phenomena, and when they were observed he never relaxed
his attention until the cause was dragged into the clear light of day.
In this case the seemingly unimportant observation that lenses pro¬
duced coloured images led him to his capital discovery of the com¬
position of white light.

Having encountered this new and unexpected complication, New¬
ton came to the conclusion that it was useless to try to perfect the
refracting telescope by improving lenses or by lengthening the tube.
In the account of his work to the Royal Society in 1672, he gives the
impression that when he began the grinding of lenses he procured a
glass prism to try the “celebrated phenomena of colours” [just what
he refers to by this phrase is obscure and, having found the unequal
refrangibility of colours, he left off his glass-works. Historians have
assumed from this statement that he had first discovered the hetero¬
geneity of white light by experimenting with a prism and then gave
up the attempt to make “lenses with surfaces other than spherical”
as it would be a waste of time. They have overlooked the quite ob¬
vious fact that, if he had discovered chromatic aberration beforehand,
he would not have attempted to make lenses at all, whereas he did

continue his work on lenses and gave it up only after he found their
defect.

It is important to trace, if possible, the sequence of Newton’s work
on light. The problem is complicated by the fact that his biographers
have depended on his reminiscences rather than on the evidence of
his contemporaneous correspondence and publications. Now New¬
ton was accurate in his recollections of what he did, but he was
singularly careless in matters of dates and the sequence of his work.
We have no evidence that he kept any orderly record of his scien¬
tific work and he certainly did not discuss it with his friends or his
teachers. But, certain facts, given in his correspondence, seem to

LUCASIAN PROFESSOR 67

establish the sequence of the ideas which led to his discovery of the
composition of white light.

We know definitely that in 1664, he made some observations with a
prism and was interested in the subject of improving the refracting
telescope, and the question is, which of the two lines of work led to
his discovery of the nature of light. It is generally stated that it
followed from his observation that the image of the sun through a
prism was oblong instead of circular. The serious objection to this
belief is that he continued to work on lenses for at least a year and
if, as he believed, their chromatic aberration was unavoidable then all
this labour was useless.

In his Optics and in his Lectures on Light, where Newton reviews
all his work, he states that he observed the images in spherical lenses
were bordered with colours which prevented a sharp focus. To find
the cause of this defect in telescopes, he prepared an oblong strip of
black paper by painting one half red and the other half blue; then he
“lapped about it several times a slender thread of very black silk, in
such a manner that the several parts of the thread might appear upon
the colours like so many black lines drawn over them.” He next
illuminated the paper strongly with candle light. With a convex
lens, he focused the black threads, which crossed the red strip, as
sharply as possible, on a sheet of white paper and he observed that
the black lines on the blue strip were out of focus and blurred. To
bring the lines on the blue strip to a sharp image, he had to move the
white screen an inch and a half closer to the lens; and then the black
lines on the red strip were indistinct. The conclusion was obvious,
the focal length of a lens depends on the colour of the light; blue is
more refracted than red and there is no sharp focus for white light.

With this fact clearly demonstrated, Newton left off his glass-works
as he believed that the unequal refrangibility of colours made it im¬
possible to perfect the refracting telescope. During the next two or
three years he carried on two lines of work; he made a little reflect¬
ing telescope, and he performed a long series of experiments with
the prism, from which he derived his laws of light.

The first achievement of Newton in optics was his construction of
a little reflecting telescope with a concave metallic mirror in place
of an object glass. The details of this instrument and the success of
the young inventor are described in the following letter.

ISAAC NEWTON

Newton to -

Trin. Coll. Cambridge,
Sir, Feb. 23,1688/9.

I promised in a letter to Mr. Ent to give you an account of my suc¬
cess in a small attempt I had then in hand: and it is this. Being
persuaded of a certain way whereby the practical part of optics might
be promoted, I thought it best to proceed by degrees, and make a
small perspective first, to try whether my conjecture would hold good
or not. The instrument that I made is but six inches in length, it
bears something more than an inch aperture, and a plano-convex eye¬
glass, whose depth is %th or /4th part of an inch; so that it magnifies
about forty times in diameter, which is more than any six feet tube
can do, I believe, with distinctness. But, by reason of bad materials,
and for want of good polish, it represents not things so distinct as a
six feet tube will do; yet I think it will discover as much as any three
or four feet tube, especially if the objects be luminous. I have seen
with it Jupiter distinctly round and his satellites, and Venus horned.
Thus, sir, I have given you a short account of this small instrument,
which, though in itself contemptible, may yet be looked upon as an
epitome of what may be done according to this way, for I doubt not
but in time a six feet tube may be made after this method, which will
perform as much, as any sixty or hundred feet tube made after the
common way; whereas I am persuaded, that were a tube made after
the common way of the purest glass, exquisitely polished, with the
best figure that any geometrician (Des Cartes, etc.) hath or can de¬
sign, (which I believe is all that men have hitherto attempted or
wished for,) yet such a tube would scarce perform as much more as
an ordinary good tube of the same length. And this, however it
may seem a paradoxical assertion, yet it is the necessary consequence

of some experiments, which I have made concerning the nature of
light.

[Is. Newton.]

This first telescope was lost, but a rumour of its success had leaked
out and by urgent request he made a second and better one which
he sent to the Royal Society. The letter itself is interesting, as it is one
of his earliest which has been preserved. There are only two earlier,
one written in January and the other in February of the same year!
Both of these are addressed to Collins who was an amateur scholar,
so enthusiastic and eager in the cultivation of correspondence that

LUCASIAN PROFESSOR

he became the scientific gazette of the time. They refer to questions
of mathematics, acknowledging the receipt of Wallis’s Mechanics
which Collins had sent to Barrow for Newton, and explaining some
of the problems involved in it. But it is also important in itself as the
last sentence settles definitely the fact that he had discovered the un¬
equal refrangibility of the spectral colours prior to the year 1669. This
letter to an unknown correspondent came into the possession of Col¬
lins who wrote on it the following memorandum, describing the re¬
ception of the telescope by the Royal Society. 7

“The telescope therein mentioned hath been lately sent up to the
Royal Society, who gave Mr. Cox order to make one after the same
manner of contrivance four feet long, the which hath been done; one
end of the tube is open, at the other end is placed a concave metalline
mirror, the diameter whereof is betwixt four and five inches; it was
ground on a sphere of fourteen feet diameter, and about its focus,
which is about four feet off, is placed a reflecting plate as big as a two¬
pence, inclined at an angle of forty-five degrees to the axis, so that the
reflected rays falling thereon, are again reflected upright to the side
of the telescope, where the eye, through a small hole, wherein is placed
a small plano-convex glass, beholds the object on the reflecting plate,
as much magnified as it could have been done by an ordinary tele¬
scope of forty feet long or more, and void of colours. The mirror and
reflecting plate are made to be taken out and wiped at pleasure; they
are not yet pleased with the metal or polish of the reflecting plate,
but are trying Lapis Osmandinus, a black stone that comes from
mount Hecla in Iceland, and other materials, whereof you may after¬
wards hear the success.

“Mr. Hooke, seeing this telescope to obtain esteem, about a month
since put in a proposal in writing to the Royal Society in words to
this effect:

“The perfection of telescopes, microscopes, scotoscopes, and burn¬
ing glasses, by figures as easily made as those that are plane or
spherical, whereby the light and magnitude of objects is prodigiously
increased, and whatsoever hath hitherto been attempted or almost de¬
sired in dioptrics accomplished-with a cipher containing the

mystery, the which he disclosed to the Lord Brouncker and Dr.
Wren, who report plausibly of it, and what is done in this way is per¬
formed by glass refraction.

7 The letter and memorandum are printed in Macclesfield’s Collection, Vol. II, p. 289.
Collins was in error in stating that this first telescope was sent to the Society.

7 °

ISAAC NEWTON

“Mr. Hooke moreover affirmed, coram multis, that in the year
1664 he made a little tube of about an inch long to put in his fob,
which performs more than any telescope of fifty feet long, made after
the common manner; but the plague happening which caused his
absence, and the fire, whence redounded profitable employments
about the city, he neglected to prosecute the same, being unwilling
the glass grinders should know any thing of the secret.”

Collins’s memorandum was not added to the original letter until
some time in the years, 1671 or 1672, when a second instrument was
exhibited to the Society. Newton was in London on July 20, 1671, be¬
cause he wrote to Collins on that day from there that he had pro¬
posed to visit him in Cambridge at the late solemnity of the installa¬
tion of the Duke of Buckingham as Chancellor of Cambridge “but
had been prevented by a sudden surprisal of a fit of sickness, which
not long after (God be thanked) he recovered of.” 8 It is possible that
he was in the city on business connected with this telescope. We are
told that it created a great stir and was examined by King Charles
II; it now forms one of the most valued possessions of the Society. 9
The invention immediately brought Newton the honour of being
proposed as a candidate for membership in the Society by Dr. Seth
Ward, Bishop of Salisbury. He was elected a Fellow on January 11,
1671/2 when the telescope was the subject of discussion. “At that
meeting mention was made of his improvement of telescopes, by
contracting them, and that that, which himself had sent thither to be
examined, had been seen by the King, and considered also by the
President, Sir Robert Moray, Sir Paul Neile, Dr. Christopher Wren,
and Mr. Hook, at Whitehall; and that they had so good an opinion
of it, as that they concluded a description, and scheme of it, should
be sent by the Secretary, in a letter on purpose, to Mr. Huggins
[Huygens] at Paris, thereby to secure this contrivance to the author,
who had also written a letter to Mr. Oldenburg from Cambridge
(Jan. 6, 1671/2) altering and enlarging the description of his instru¬
ment, which had been sent hence for his review, before it should go
abroad.” 10

Newton was immensely surprised and gratified with the enthu-

8 Macclesfield, II, p. 308.

9 Edleston, p. xlv. Collins writing to Vernon, English Secretary at Paris, December
26, says: “As to Mr. Newton’s Telescope, I suppose Mr. Bernard (of Oxford) writ the same
to you as he did to me upon the authority of one Mr. Gale of Cambridge [Fellow of Trin.
Coll, and afterwards Dean of York]: since it hath been brought up for his Majesty’s
perusal, and I have seen an object in it,”

10 Journ. Boo\, R. S,

LUCASIAN PROFESSOR

7 i

siasm which his invention had aroused. A detailed account of his
plans for perfecting his telescope, and his attempts to find the proper
alloy which would receive a high polish and be suitable for large
metallic mirrors is preserved for us in a long series of letters, mostly
addressed to Oldenburg. 11 I can thus give, by extracts from these
letters, Newton’s own account of his discovery and his efforts to make
his ideas acceptable to the scientific world. Since the members of the
Society had ordered their Secretary, Oldenburg, to protect Newton’s
rights of priority in his telescope by sending letters to learned men
and, especially, to Huygens, he accordingly asked Newton to prepare
a memorandum describing his instrument.

Newton to Oldenburg

g* r Cambridge, Jan. 6,1671/2.

At the reading of your letter I was surprised to see so much care
taken about securing an invention to me, of which I have hitherto
had so little value. And therefore since the Royal Society is pleased
to think it worth the patronising, I must acknowledge it deserves
much more of them for that, than of me, who, had not the com¬
munication of it been desired, might have let it still remain in
private as it hath already done some years. ... I am very sensible of
the honour done me by the Bishop of Sarum in proposing me candi¬
date, and which I hope will be further conferred upon me by my
election into the society. And if so, I shall endeavour to testify my
gratitude by communicating what my poor and solitary endeavours
can effect towards the promoting your philosophical designs.

Sir, I am

Your very humble servant,

I. Newton.

There followed a frequent correspondence relating mostly to the
best method for grinding and polishing concave mirrors and pre¬
paring a metallic alloy which would take and preserve a sufficiently
high polish. The Society had put this work into the hands of Cox,
the most expert glass-worker in London—but the problem proved
to be too difficult for him, and Newton was entirely too busy to devote

11 These letters are published in Horsley’s Opera Omnia Newtoni and in Macclesfield’s
Collection.

ISAAC NEWTON

his own time to the practical work. As a result, reflecting telescopes
of a large and useful size were not made until more than fifty years
later. I shall omit the now uninteresting particulars of these attempts
and abstract only those portions of the letters which throw light on
Newton’s character and life.

The first of these extracts is taken from a letter of date January 18,
1671/2 and is memorable as the first public announcement of his
new discoveries as to the nature of light: “I desire that in your next
letter you would inform me for what time the society continue their
weekly meetings; because, if they continue them for any time, I am
purposing them, to be considered of and examined, an account of a
philosophical discovery, which induced me to the making of the
said telescope, and which I doubt not but will prove much more
grateful than the communication of that instrument, being in my
judgement the oddest, if not the most considerable detection, which
hath hitherto been made in the operations of nature A 12

This “detection,” which I have italicised, refers, of course, to the
heterogeneous character of white light. Nothing could better illus¬
trate the general lack of interest in science and the isolation of the
universities from London, than the fact that this great discovery
had been made in Cambridge, and had been described in a public
course of lectures for two successive years, and yet was still unknown
to members of the Royal Society five years after it had been made.
It is even more remarkable from the fact that Newton claimed the
importance of what he had done and expressed satisfaction and en¬
thusiastic pleasure in his work. At this time, he was eager to enjoy
popular renown. Warmed by the flattering reception his telescope
had received, he felt that he could show his appreciation for his
election to the Royal Society in no way better than by offering a
serious scientific communication. Accordingly, he sent a long letter
to Oldenburg elucidating the hint of that “oddest, if not the most
considerable detection, which hath hitherto been made in the opera¬
tions of nature.”

A Letter of Mr. Isaac Newton, Professor of Mathematics in the
University of Cambridge; containing his New Theory of Light and
Colours: sent by the Author to the Editor from Cambridge, Feb. 6,
1671/2; to be communicated to the Royal Society and published in
their Transactions. 13

12 Macclesfield, Vol. II, 315; Horsley, Vol. Ill, p. 274. 13 Phil. Trans., No. 80, p. 3075.

LUCASIAN PROFESSOR

Sir,—To perform my late promise to you, I shall without further
ceremony acquaint you, that in the beginning of the year 1666 (at
which time I applied myself to the grinding of optic glasses of
other figures than spherical,) I procured a triangular glass prism, to
try therewith the celebrated phenomena of colours. And for that
purpose having darkened my chamber, and made a small hole in my
window shuts, to let in a convenient quantity of the sun’s light, I
placed my prism at his entrance, that it might be thereby refracted
to the opposite wall. It was at first a very pleasing diversion to view
the vivid and intense colours produced thereby; but after a while
applying myself to consider them more circumspectly, I was sur¬
prised to see them in an oblong form; which, according to the re¬
ceived laws of refraction, I expected would have been circular. They
were terminated at the sides with straight lines, but at the ends, the
decay of light was so gradual, that it was difficult to determine justly
what was their figure; yet they seemed semicircular.

Comparing the length of this coloured spectrum with its breadth,
I found it about five times greater; a disproportion so extravagant,
that it excited me to a more than ordinary curiosity of examining
from whence it might proceed. I could scarcely think, that the vari¬
ous thickness of the glass, or the termination with shadow or
darkness, could have any influence on light to produce such an
effect; yet I thought it not amiss, first to examine those circumstances,
and so tried what would happen by transmitting light through parts
of the glass of divers thicknesses, or through holes in the window of
divers sizes, or by setting the prism without, so that the light might
pass through it, and be refracted before it was terminated by the hole;
but I found none of those circumstances material. The fashion of the
colours was in all these cases the same.

Then I suspected, whether by any unevenness in the glass, or other
contingent irregularity, these colours might be thus dilated. And
to try this, I took another prism like the former, and so placed it, that
the light, passing through them both, might be refracted contrary
ways, and so by the latter returned into that course from which
the former had diverted it. For, by this means, I thought the regular
effects of the first prism would be destroyed by the second, but the
irregular ones more augmented, by the multiplicity of refractions.
The event was, that the light, which by the first prism was diffused
into an oblong form, was by the second reduced into an orbicular one,
with as much regularity as when it did not at all pass through them.

ISAAC NEWTON

So that, whatever was the cause of that length, it was not any con¬
tingent irregularity.

I then proceeded to examine more critically, what might be effected
by the difference of the incidence of rays coming from divers parts of
the sun; and to that end measured the several lines and angles, belong¬
ing to the image. . . .

Having made these observations, I first computed from them the
refractive power of that glass, and found it measured by the ratio of
the sines, 20' to 31'. And then, by that ratio, I computed the refractions
of two rays flowing from opposite parts of the sun’s discus, so as to
differ 31' in their obliquity of incidence and found that the emergent
rays should have comprehended an angle of about 31', as they did,
before they were incident. But because this computation was founded
on the hypothesis of the proportionality of the sines of incidence and
refraction, which though, by my own experience, I could not imagine
to be so erroneous as to make that angle but 3T, which in reality was
2 ° 49 > yet my curiosity caused me again to take my prism. And
having placed it at my window, as before, I observed, that by turning
it a little about its axis to and fro, so as to vary its obliquity to the
light, more than an angle of 4 or 5 degrees, the colours were not
thereby sensibly translated from their place on the wall, and conse¬
quently by that variation of incidence, the quantity of refraction was
not sensibly varied. By this experiment therefore, as well as by the
former computation, it was evident, that the difference of the inci¬
dence of rays, flowing from divers parts of the sun, could not make
them, after a decussation, diverge at a sensibly greater angle, than
that at which they before converged; which being at most but about
31 or 32 minutes, there still remained some other cause to be found
out, from whence it could be 2 0 49'.

Then I began to suspect whether the rays, after their trajection
through the prism, did not move in curve lines, and according to their
more or less curvity tend to divers parts of the wall. And it in¬
creased my suspicion, when I remembered that I had often seen a
tennis ball, struck v/ith an oblique racket, describe such a curveline.
For, a circular as well as a progressive motion being communicated to
it by that stroke, its parts on that side, where the motions conspire,
must press and beat the contiguous air more violently than on the
other, and there excite a reluctancy and reaction of the air proportion-
ably greater. And for the same reason, if the rays of light should
possibly be globular bodies [Descartes’s hypothesis], and by their

LUCASIAN PROFESSOR

oblique passage out of one medium into another acquire a circulating
motion, they ought to feel the greater resistance from the ambient
aether, on that side where the motions conspire, and thence be contin¬
ually bowed to the other. But notwithstanding this plausible ground
of suspicion, when I came to examine it, I could observe no such
curvity in them. And besides (which was enough for my purpose) I
observed, that the difference between the length of the image and
diameter of the hole, through which the light was transmitted, was
proportionable to their distance.

The gradual removal of these suspicions, at length led me to
the experimentum cruris, which was this: I took two boards, and
placed one of them close behind the prism at the window, so that
the light might pass through a small hole, made in it for the pur¬
pose, and fall on the other board, which I placed at about 12 feet
distance, having first made a small hole in it also, for some of that
incident light to pass through. Then I placed another prism behind
this second board, so that the light, trajected through both the boards,
might pass through that also, and be again refracted before it arrived
at the wall. This done, I took the first prism in my hand, and turned
it to and fro slowly about its axis, so much as to make the several parts
of the image, cast on the second board, successively pass through the
hole in it, that I might observe to what places on the wall the second
prism would refract them. And I saw, by the variation of those places,
that the light tending to that end of the image, towards which the
refraction of the first prism was made, did in the second prism suffer
a refraction considerably greater than the light tending to the other
end. And so the true cause of the length of that image was detected
to be no other, than that light consists of rays differently refrangible,
which, without any respect to a difference in their incidence, were,
according to their degrees of refrangibility, transmitted towards
divers part of the wall.

When I understood this, I left off my aforesaid glass works; for I
saw, that the perfection of telescopes was hitherto limited, not so
much for want of glasses truly figured according to the prescriptions
of optic authors, (which all men have hitherto imagined,) as because
that light itself is a heterogeneous mixture of differently refrangible
rays. So that, were a glass so exactly figured, as to collect any one
sort of rays into one point, it could not collect those also into the
same point, which having the same incidence upon the same medium
are apt to suffer a different refraction. Nay, I wondered, that seeing

7 6

ISAAC NEWTON

the difference of refrangibility was so great, as I found it, telescopes
should arrive to that perfection they are now at. . . .

I shall now proceed to acquaint you with another more notable
difformity in its rays, wherein the origin of colours is unfolded: con¬
cerning which I shall lay down the doctrine first, and then, for its
examination, give you an instance or two of the experiments, as a
specimen of the rest.—The doctrine you will find comprehended and
illustrated in the following propositions:—

1. As the rays of light differ in degrees of refrangibility, so they
also differ in their disposition to exhibit this or that particular colour.
Colours are not qualifications of light, derived from refractions, or
reflections of natural bodies (as it is generally believed,) but original
and connate properties, which in divers rays are diverse. Some rays
are disposed to exhibit a red colour, and no other; some a yellow, and
no other; some a green, and no other; and so of the rest. Nor are there
only rays proper and particular to the more eminent colours, but even
to all their intermediate gradations.

2. To the same degree of refrangibility ever belongs the same
colour, and to the same colour ever belongs the same degree of
refrangibility. The least refrangible rays are all disposed to exhibit a
red colour, are all the least refrangible; so the most refrangible rays
are all disposed to exhibit a deep violet colour, and contrarily, those
which are apt to exhibit such a violet colour, are all the most refran¬
gible. And so to all the intermediate colours, in a continued series,
belong intermediate degrees of refrangibility. And this analogy be¬
twixt colours, and refrangibility is very precise and strict; the rays
always either exactly agreeing in both, or proportionally disagreeing
in both.

3. The species of colour, and degree of refrangibility proper to any
particular sort of rays, is not mutable by refraction, nor by reflection
from natural bodies, nor by any other cause, that I could yet observe.
When any one sort of rays has been well parted from those of
other kinds, it has afterwards obstinately retained its colour, not¬
withstanding my utmost endeavours to change it. I have refracted
it with prisms, and reflected it with bodies, which in day-light were
of other colours: I have intercepted it with the coloured film of air
interceding two compressed plates of glass; transmitted it through
coloured mediums, and through mediums irradiated with other
sorts of rays, and diversely terminated it; and yet could never produce
any new colour out of it. It would, by contracting or dilating, become

LUCASIAN PROFESSOR

more brisk, or faint, and by the loss of many rays, in some cases
very obscure and dark; but I could never see it change in specie. . . .

The Society: “ordered, that the author be solemnly thanked, in
the name of the Society, for this very ingenious discourse, and be
made acquainted that the Society think very fit, if he consents to have
it forthwith printed, as well for the greater conveniency of having
it well considered by philosophers, as for securing the considerable
notices thereof to the author against the arrogations of others.
Ordered also, that the discourse be entered in the register-book, and
that the Bishop of Salisbury, Mr. Boyle, and Mr. Hook, be desired to
peruse and consider it, and bring in a report of it to the Society.” 14

This first published article by Newton produced such an extraordi¬
nary effect on his contemporaries and had such an influence on his
life and character that I shall examine it critically and show why it
marked a new era in science. In the first place, it is an almost perfect
model in both form and content. It is the more remarkable because
Newton had no example to follow; it is significant of his genius that
his first essay was as perfect as was his later work. His mind seemed
to need no period of growth but to have reached its full maturity at
once.

In form, the article is a work of art—clear, concise, and admirably
arranged to lead the reader from a dramatic introduction straight to a
convincing conclusion. He, certainly, made many observations which
must have been useless; but from his notes he selected those which
were pertinent and forbore to weary and confuse his readers by giv¬
ing a mass of irrelevant details. That is, contrary to custom, he
relied on a few carefully selected experiments to prove his thesis.

He opens with the apparently insignificant observation that the
spectrum was oblong, whereas “the received laws of refraction”
would lead him to expect that it would be circular in conformity with
the shape of the source of light or of the aperture in the shutter. It
is the business of science to investigate just such discrepancies be¬
tween facts and ideas. As has been pointed out, he probably had his
attention first drawn to this research by his work on lenses.

The correct procedure was then to determine the cause of this
observed fact. He wisely examines first those causes which would be
supported by the accepted laws of refraction. He carries through a

14 Jour. Boo\, R. S.

ISAAC NEWTON

series of experiments which prove that the unevenness and compo¬
sition of the prism, the size and shape of both the source and the
aperture, and the possible propagation of light in curved lines had
no effect on the oblong form of the spectrum.

Having thus cleared away all the possible sources of error that he
can imagine, he goes straight to the true cause. He prepares what he
calls an expenmentum crucis, one which will convince an impartial
reader that it was due to an unsuspected property of light itself.
Lastly, he sums up his whole work in three laws, which involve no
speculation, or hypothesis, and can be denied only by proving that his
experimental evidence was false or inexact.

Thus, at the very beginning of his career he had grasped the idea
that the true function of science is to observe and classify a set of
selected phenomena and from them to formulate laws which will
predict, as accurately as possible, future events. To go further than
this, to imagine the mechanism which operates to produce the
phenomenon, is to pass from the field of physics into metaphysics 15
where there is no criterion of knowledge. His early distrust of meta¬
physics was intensified by the criticisms which his scientific method
aroused. It seemed to him self-evident that the laws he had found
could be attacked only by other experimental evidence which would
give new facts or prove that his own were in error. Yet, to his amaze¬
ment and chagrin, he found that even the masters of science refused
to accept those laws because they did not conform to their precon¬
ceived hypotheses as to the nature and cause of light and colour. As
a result, he discarded hypothesis from science altogether, and in the
Principia he summed up his convictions in the famous phrase,
hypotheses non fingo. He thus denied that we have any a priori
knowledge of the constitution of nature; the world is as it is, and
it is the business of the man of science to find the facts. A theory, to
Newton, was a law based on indisputable facts, expressed in mathe¬
matical terms, which could be overthrown only by discovering new
facts or by proving others to be false. An hypothesis was merely a
speculation as to the cause or the method of phenomena. As all hy¬
potheses ultimately, in his opinion, introduced occult forces or sub¬
stances, they were not only incapable of verification, but many
entirely different hypotheses could be imagined to explain any single
set of phenomena. They, then, not only give us no positive knowl-

1 ®The word metaphysics, as used here, must not be confused with philosophy. It refers
to those speculations on natural phenomena which cannot be put to the test of experimental
observation.

LUCASIAN PROFESSOR

edge but they actually breed confusion and make men suppose they
understand what they do not. If they are indulged in, they should
be no more than the picture of a real scene, an aid to the memory. As
we can mark the beginning of the scientific Renaissance by the work
of Copernicus, so we can close that period and begin modern science
with Newton’s first published work.

It is usually stated that Copernicus, Kepler, Galileo, and Descartes
were the inaugurators of modern science. That is true in part, but the
older methods still clung to them. While they attacked the dogmatic
and Aristotelian metaphysics, they often drew their own deductions
from an a prion and inward sentiment of knowledge. Kepler’s trea¬
tises are full of excursions into foreign fields; every observation he
makes is detailed to our distraction, and wild speculation jostles
his soberest description of facts. Galileo, marvellous experimentalist
though he was, throws his two great works into the form of inter¬
minable dialogues, in which he devotes himself to attacking the
Aristotelians by Aristotelian logic more earnestly than he gives the
results of his observation.

As for Descartes and his school, I cannot contrast them better with
the wholesome method of Newton than by quoting Lord Boling-
broke: “The notion he [Descartes] entertained and propagated, that
there is, besides clear ideas, a kind of inward sentiment of evidence,
which may be a principle of knowledge, is, I suppose, dangerous in
physical enquiries as well as in abstract reasoning. He who departs
from the analytic method, to establish general propositions concern¬
ing the phenomena on assumptions, and who reasons from these as¬
sumptions, afterwards on inward sentiments of evidence, as they are
called, instead of clear and real ideas, lays aside at once the only sure
guides to knowledge. No wonder then if he wanders from it. This
Des Cartes did very widely in his construction of a world; and yet
by dint of genius he gave a great air of simplicity and plausibility to
his hypothesis, and he knew how to make even geometry subservient
to error.. . . How slowly, how unwillingly have many philosophers
departed from the cartesian hypothesis.” 16

If modern science, two hundred years after Newton, still debauches
itself with hypotheses of aethers, electronic structures, and fantastic
cosmogonies, we can easily imagine the opposition aroused by this
young and unknown man who boldly and laconically challenged hy¬
pothetical dogmatism, who put the evidence of his experimentation

10 Letters or Essays Addressed to Alexander Pope, Esq., Works (1754), Vol. I, pp. 62, 63..

ISAAC NEWTON

against the accepted ideas of the day, supported by the weight of
authority of Kepler, Descartes, and the other foremost men of science.

No wonder there was a controversy. Men of keen minds, even
such as a Huygens and a Hooke, could not understand what New¬
ton meant, and resented the fact that they were curtly forbidden to
answer him with their opinions, coined from their inward sentiment
of knowledge. His only reply to their arguments was; stop telling me
what so and so thinks, but prove my results are wrong or provide new
and different results. Newton’s biographers refer to his opponents as
being men who wearied Newton with foolish and silly objections.
But they were not foolish men, they were merely opposing theory by
hypothesis. They were doing exactly what the followers of hypo¬
thetical science today are doing, who create a fantastic world and
maintain it against the stubborn facts of experience.

Newton, himself, became a marked man; he had introduced a new
scientific method and henceforth treatises were expected to be
pruned of redundant and extraneous matter. But the effect on New¬
ton was disastrous. Totally unfit both by natural disposition, and by
training, to encounter the egotistic hardness of men, he shrank from
the hostility of vanity and the stolidity of custom. The attack made
on him personally, and on his veracity—coming instead of the
cordial reception of new ideas which he had expected—frightened
him, and led him to desire Oldenburg to soften any harsh word that
might escape him lest further opposition should be aroused. His
naive expression of pleasure changed to disgust, and he accused
nature as well as men of being litigious; to enjoy peace of mind, he
resolved in future to meditate, but not impart his cogitations to a
carping public.

Before closing the chapter, a matter must be discussed which has
never been explained and probably never will be. Barrow, before
resigning his professorship, had edited his Lucasian Lectures on Light
and published them in 1669, the year in which Newton began his
course on the same subject. In the preface to the work, Barrow gen¬
erously acknowledges his indebtedness to Newton, as a young man
of excellent character and of great genius, who had criticised the
manuscript and corrected the proofs. 17

17 “Verum quod tenellae matres factitant, a me depulsum partum amicorum haud recu-
santium nutriciae curae commisi, prout ipsis visum esset, educandum aut exponendum, quorum
unus (ipsos enim honestum duco nominatim agnoscere) D. Isaacus Newtonus, collega noster
(peregregiae vir indolis ac insignis peritiae) exemplar revisit, aliqua corrigenda monens, sed
et de suo nonnulla penu suggerens quae nostris alicubi cum laude innexa cernes.” Epist. ad
Lectorem.

LUCASIAN PROFESSOR

Now, the puzzle is this. Barrow’s published lectures do not contain
a single reference to the fact that Newton had worked independently
in the subject of light; or show any acquaintance with his discovery
of chromatic aberration, the construction of a reflecting telescope, the
selective refrangibility of colours, and the composition of white
light. Instead, the author gives the accepted and erroneous explana¬
tion of all of those subjects. Yet his young protege, while the printing
was in process, kept his own counsel and, from any evidence we have,
never mentioned his work. Furthermore, when the book was first
in the hands of the public and of the University students, Newton
was delivering his lectures which contradicted and made much of his
master’s work false.

It is quite inconceivable that Barrow would have permitted his
book to be published if he had known about Newton’s work. He
was too able a scientist not to have recognised its importance and at
least to have alluded to it. And if Newton kept his work and its re¬
sults absolutely to himself, what were his motives ? Was it a case of
that excessive modesty with which his biographers have endowed
him ? But Newton called his discovery “the oddest, if not the most
considerable detection, which hath hitherto been made in the opera¬
tions of nature”; and such a statement does not express any failure
to recognise his own worth. Or, was it the first case of his sensitive
and suspicious jealousy which made him regard his thoughts as his
own and made him resent any intrusion of others in the same field ?

The question just raised is more difficult to answer than, appar¬
ently, Brewster admitted. He easily explained the incident by simply
denying the facts. “It does not appear,” he says, “from any of the
documents which I have seen, at what time Newton made his first
optical discoveries. . . . And there is every reason to believe that he
was not acquainted with the true composition when Dr. Barrow
completed his Optical Lectures, published in 1669.” 18 Whatever may
be the answer, Brewster has certainly not given it. The incident will
continue to be cited by some as an example of Newton’s great mod¬
esty; by others it will be regarded as one of those exhibitions of jeal¬
ousy, or vanity, which caused him such bitter quarrels in his later life.

18 Brewster, Vol. I, p. 27. If Brewster did not see any documents which prove that
Newton knew the composition of white light, etc., before 1669, he must have shut his
eyes to Newton’s letter of Feb. 23, 1668/9, to his Lucasian lectures on light published in
Horsley, to the letter to Oldenburg of Jan.. 18, 1671/2, and to his first paper published
in the Phil. Trans., which is a resume taken from his lectures. No help can be obtained
from the MSS. in the Portsmouth Collection as none of them refers to his early work on
light.

CHAPTER IV

ARGUMENT ON THE NATURE OF LIGHT. NEWTON ON

THEORY AND HYPOTHESIS

N ewton's conception of the scientific method was clearly
brought out in his first published work on light, and the
discussion which it aroused forced him to formulate his
ideas on the mechanistic philosophy of physical phenomena. And
while his Principia is his greatest achievement, he continued to ex¬
periment and meditate more consecutively on the subject of light
than on any other except perhaps chemistry. He also chose to at¬
tach his general cosmical and philosophical meditations to his treatise
on Optics in the form of Queries. As this book was not published
till 1709, I shall devote this chapter to a connected outline of his
theory of light and his philosophical method although it will neces¬
sitate a considerable amount of repetition when the events of his life
are narrated chronologically. Only in this way can continuity of his
ideas be presented, and in the career of such a man they are more im¬
portant than his outward life.

The importance Newton, at the age of thirty, attached to his dis¬
coveries in light is clearly indicated in his letter to Oldenburg where
he wrote of them as “the oddest, if not the most considerable detec¬
tion, which hath hitherto been made in the operations of nature.” 1
But I believe he was convinced that the method by which he had
made these “detections” was more important than the “detections”
themselves. He saw clearly that the revolt against the Aristotelian
deductive method, begun by Galileo, could lead to but one conclu¬
sion; science is limited to experimentation and to formulation of
laws which together constitute a theory. It is only by keeping this
in mind that we can appreciate his long polemic against hypothetical
reasoning.

We have seen in Chapter III that the first action of the Royal
Society, when it received Newton’s first great paper on light, was to
appoint a committee to appraise the value of his new theory of light,

1 Cf . Chapter III, p„ 72.

ARGUMENT ON THE NATURE OF LIGHT

and to safeguard his right of priority by instructing Oldenburg to
communicate its contents to Huygens as the one whose opinions
would carry the greatest weight. The committee, at once, brought
in their report, which was written and read by Hooke, at the next
meeting on February 15, 1671/2. The report, in my judgement, is
eminently fair, giving Newton full credit for his ingenious experi¬
ment and differing from him only on the ground that he had not
proved that a vibration theory would not also explain his results.

Hooke reported in part: “I have perused the discourse of Mr.
Newton about colours and refractions, and I was not a little pleased
with the niceness and curiosity of his observations. But, tho’ I wholly
agree with him as to the truth of those he hath alleged, as having, by
many hundreds of trials, found them so; yet as to his hypothesis of
solving the phenomena of colours thereby, I confess, I cannot see yet
any undeniable argument to convince me of the certainty thereof.
For all the experiments and observations I have hitherto made, nay,
and even those very experiments, which he allegeth, do seem to me to
prove, that white is nothing but a pulse or motion, propagated
through an homogeneous, uniform, and transparent medium; and
that colour is nothing but the disturbance of that light, by the com¬
munication of that pulse to other transparent mediums, that is, by the
refraction thereof: that whiteness and blackness are nothing but the
plenty or scarcity of the undisturbed rays of light: and that the two
colours (than the which there are not more uncompounded in
nature) are nothing but the effects of a compounded pulse, or dis¬
turbed propagation of motion caused by refraction.

“But, how certain soever I think myself of my hypothesis (which I
did not take up without first trying some hundreds of experiments)
yet I should be very glad to meet with one experitnentutn cyucis from
Mr. Newton, that should divorce me from it. But it is not that, which
he so calls, will do the turn; for the same phenomenon will be
solved by my hypothesis, as well as by his, without any manner of
difficulty or training: nay, I will undertake to shew another hypoth¬
esis, differing from both his and mine, that shall do the same
thing. ...

“Nor would I be understood to have said all this against his theory,
as it is an hypothesis; for I do most readily agree with it in every part
thereof, and esteem it very subtile and ingenious, and capable of
solving all the phenomena of colours: but I cannot think it to be
the only hypothesis, nor so certain as mathematical demonstrations.”

8 4

ISAAC NEWTON

The report, after it was read, was ordered to be registered and a
copy to be sent to Newton. “And that in the mean time the printing
of Mr. Newton’s discovery by itself might go on, if he did not con¬
tradict it; and that Mr. Hooke’s paper might be printed afterwards,
it not being thought fit to print them together, lest Mr. Newton
should loo\ upon it as a disrespect, in printing so sudden a refutation
of a discourse of his, which had met with so much applause at the
Society hut a few days before !’ 2

Hooke has been severely blamed by the partisans of Newton for
his harsh treatment of the young philosopher, but his early criticism
is in a perfectly proper tone. Undoubtedly, two men of such irritable
temperament were almost certain to disagree, but much of the bitter¬
ness which followed can be laid at the door of Oldenburg, who dis¬
liked Hooke and certainly did nothing to ease the situation. That
Newton was quite satisfied with the reception of his discourse and
had no fault to find with the criticisms of either Huygens or Hooke
is shown by his answer to Oldenburg.

Newton to Oldenburg

Sir,

Cambridge, Feb. 20, 1671/2.

I received your’s [of] Feb. 19th. And having considered Mr.
Hooke’s observations on my discourse, am glad that so acute an ob¬
jector hath said nothing that can enervate any part of it. For I am
still of the same judgement, and doubt not but that upon severer ex¬
aminations, it will be found as certain a truth as I have asserted it.
You shall very suddenly have my answer.

In Mons r . Hugenius’s letter there are several handsome and in¬
genious remarks. And what he saith concerning the grinding para¬
bolical conoids by geometrical rules, I do with him despair of; but I
doubt not but that the thing may be in some measure accomplished
by mechanical devices. This is all at present from

your faithful servant,

I. Newton. 3

For some unknown reason, the published correspondence between
Oldenburg and Huygens and the articles of Huygens and Newton on

2 Birch, III, p. 9 seq.—It was not printed in the Transactions.

3 Macclesfield, Vol. II, p. 318.

ARGUMENT ON THE NATURE OF LIGHT

the subject suppress Huygens’s name and he is referred to as “an

ingenious person of Paris, or as Monsieur N.” It is from his collected

works that we find that Oldenburg kept him acquainted with the
whole discussion.

The attitude of Huygens presents a curious conflict of opinion
arising from two different traits of his character. On the one hand
he was a great experimentalist and he immediately appreciated the
elegance and rigour of Newton’s observations. So he answered
Oldenburg: Concerning his new theory of colours, it seems to me
most ingenious, but it is necessary to see whether it is compatible
with all experience. This favourable answer was most gratifying
to the young scientist. But Pluygens was also strongly committed to
the refracting telescope and Newton had, perhaps, irritated him by
his rather brusque advocacy of the superiority of the reflecting type.
He was, also, an adherent of the Cartesian philosophy; and he had
expanded the Cartesian hypothesis of the nature of light into a tenta¬
tive theory of wave transmission, which had the support of the in¬
genious experimentalist Robert Hooke. As it became more apparent
to him that these new experiments were difficult to reconcile with his
and Hooke’s hypothesis of waves, and its corollary that two primary

•"° our *’. re< ^. an ^ combined to produce all other colours includ¬
ing white light, his habit of relying upon “an inward sentiment of
knowledge began to confuse his judgement and he wrote three
months later: “Concerning his new hypothesis of colours ... I con¬
fess that it appears quite probable, and the expenmentum cruets (if
1 understand it correctly, for it is expressed rather obscurely) con¬
firms it well.” Thus, even he could not grasp the idea of the finality
o Newton s experiments and formulation of laws from them, since
he believed their truth and value lay in whether they confirmed this
or that hypothesis of the nature and cause of light. In other words,
the diversity of colours was not an objective fact but something
dependent on our preconception of the nature of light. So he a^ain
wrote to Oldenburg: “What you have published in°a recent number
or the Transactions greatly strengthens his doctrine of colours. At the
same time the cause of light may be something quite different, and
it seems to me that he should content himself that, what he had ad¬
vanced, may pass for a probable hypothesis. Besides, if it should be

4 C/. CEuvres d’Huygens, t. VII; Macclesfield Collections, Vol. II, np. agi-tae passim •
Horsley, Vol. Ill, Letters passtm.; PHI. Trans., Nos. 9 6, p. 6086; 97 , pp. 6108, 61,2

ISAAC NEWTON

true that the rays of light, in their original state, were some red,
others blue, etc. there would still remain the great difficulty of ex¬
plaining, by mechanical principles, in what consists this diversity of

colours.”

The inability of Huygens to grasp the significance of his work was
a bitter disappointment to Newton. He had patiently explained his
experiments. He had reiterated that they involved no hypothesis
as to the cause or nature of light; that the function of real science was
to discover a well thought out series of experiments and to classify
them in laws; and that any ingenious person could imagine mechan¬
ical hypotheses of many kinds which were, at best, mere mental pic¬
tures and not science. If he could not convince Huygens, what
chance was there with inferior men? In the bitterness of his dis¬
appointment, he rebuked, in a published article, this inability of
Huygens to see his point of view: “I confess it was a little ungrate¬
ful to me to meet with objections which had been answered before,
without having the least reason given me why those answers were in¬
sufficient.” He also wrote in his familiar letters that he was minded
to forsake science altogether or, at least, never again to expose him¬
self to the litigious altercations which were the fate of any one who
published new ideas.

Newton’s first critic in print was Father Ignatius Pardies, the dis¬
tinguished professor of natural philosophy in the College of Cler¬
mont at Paris. In a letter published in the Philosophical Transac¬
tions^ Pardies pointed out that this work, if substantiated, overturned
the accepted hypothesis of the nature of light. Imbued with the prac¬
tice of the day that a multitude of observations must be made before
a correct conclusion may be drawn, he objected vigorously because
so revolutionary a doctrine “is founded entirely on the experiment
of the prism, in which rays entering a dark room through a hole in
a window-shutter, and then falling on the wall, or received on a
paper, did not form a round figure, as he expected according to the
received rules of refraction.” He then gave his own explanations
why the spectrum should be oblong. He next considered the experi-
mentum crucis, which he evidently misunderstood and with some
justification since Newton’s statement is not only too condensed but
is somewhat obscure, and stated that it is explicable without recourse
to his new theory of the heterogeneity of white light. He, lastly,
maintained that Newton’s experiments on the mixture of colours to

5 No. 84 (1672), pp. 4087-4090.

ARGUMENT ON THE NATURE OF LIGHT

produce white were not conclusive; but he admitted that he had in¬
geniously and properly refuted Hooke’s ideas of primary colours.

The whole critique was so temperately and appreciatively ex¬
pressed that Newton answered all the objections carefully and fully.
He took the opportunity to close his letter with an admonition
against trying to make the laws of nature conform to our precon¬
ceived speculations: “I do not take it amiss that the Rev. Father calls
my theory an hypothesis, inasmuch as he is not acquainted with it.
But my design was quite different, for it seems to contain only cer¬
tain properties of light, which, now discovered, I think easy to be
proved, and which if I had not considered them as true, I would
rather have them rejected as vain and empty speculation than
acknowledged even, as an hypothesis.” 6 In a second letter 7 Pardies,
although not convinced, acknowledged that he had not read the
experimentum crucis carefully; apologised for calling the author’s
theory an hypothesis, and complimented the “excellent Newton” for
his ingenious discoveries.

Newton was deeply touched with his critic’s fairness and could
“hardly determine whether there is more of humanity and candour,
in allowing my arguments their due weight, or penetration and
genius in starting objections.” He, then, again explained his experi¬
ments fully and carefully. Warmed by so appreciative a critic,
Newton laid aside his reserve and gave expression to his ideas on the
scientific method in what may be justly called the Golden Rule of
Science: “For the best and safest method of philosophising seems to
be, first to enquire diligently into the properties of things, and of
establishing those properties by experiments, and then to proceed
more slowly to hypotheses for the explanation of them. For hypoth¬
eses should be subservient only in explaining the properties of
things, but not assumed in determining them; unless so far as they
may furnish experiments. For if the possibility of hypotheses is to be
the test of the truth and reality of things, I see not how certainty can
be obtained in any science; since numerous hypotheses may be de¬
vised, which shall seem to overcome new difficulties. Hence it has
been here thought necessary to lay aside all hypotheses, as foreign to
the purpose, that the force of the objection should be abstractedly
considered, and receive a more full and general answer. ... As to
the Rev. Father’s calling our doctrine an hypothesis, I believe it only
proceeded from his using the word which first occurred to him, as a

6 Phil. Trans., No. 84 , p., 4091 . 7 Ibid., No. 85, p. 5012.

ISAAC NEWTON

practice has arisen of calling by the name hypothesis whatever is
explained in philosophy: and the reason of my making exception to
the word, was to prevent the prevalence of a term, which might be
prejudicial to true philosophy.” 8

After Pardies had read this letter he appended the following note:
“I am quite satisfied with Mr. Newton’s answer to me. The last
scruple which I had, about the experimentum crucis, is fully removed.
And I now clearly perceive by his figure what I did not before un¬
derstand. When the experiment was performed after his manner,
everything succeeded, and I have nothing further to desire.” So
ended a controversy conducted with propriety and courtesy on both
sides. But Newton had to submit to two other long-drawn-out alter¬
cations, which cut deeply into his precious time and meditations, and
which the officious Oldenburg should have prevented. One was
marked by stupidity, and the other was irritating because it arose
from jealousy and vanity.

The enquiries and objections of Huygens had the desired effect of
calling the attention of men of science to the revolutionary ideas of
Newton, and Oldenburg, in one of his letters to Huygens, expressed
his belief that the new ideas were gaining ground. But they were
not to be accepted without protest. On October 6, 1674, a letter was
published in the Philosophical Transactions 9 by the “learned” Francis
Linus, professor of mathematics in the College of English Jesuits at
Liege, sharply criticising Newton’s experimental work. The author
stated that he had performed similar experiments thirty years pre¬
viously and many times since then, and had found the same length¬
ening of the spectrum. But he had traced the phenomenon to its true
cause and found that it was due to scattered light, either because the
prism had been placed at a considerable distance from the aperture
admitting the sun-light, or because “the sun either shined through a
white cloud, or enlightened some such clouds near unto it. Other¬
wise the spectral image of the sun was circular as the prevalent
theory demanded.”

Oldenburg, with his customary fussiness, immediately wrote to
Newton urging him to reply to this criticism which would have died
from its own folly if left alone. Newton flatly refused to become in¬
volved, and expressed his disgust of this frivolous intrusion on his
time.

8 Phil. Trans., No. 85, p. 5014.

9 Ibid., No. no, p. 217.

ARGUMENT ON THE NATURE OF LIGHT

Newton to Oldenburg

Sir,

Cambridge, Dec. 5, 1674.

I am sorry you put yourself to the trouble of transcribing Fr.
Linus’s conjecture, since (besides that it needs no answer) I have
long since determined to concern myself no further about the pro¬
motion of philosophy. And for the same reason I must desire to be
excused from engaging to exhibit yearly philosophic discourses, but
yet cannot but acknowledge the honour done me by your council,
to think of me for one amongst that list of illustrious persons, who
are willing to perform it, and therefore desire to have my thanks re¬
turned to them for the motion. If it were my lot to be in London
for some time, I might possibly take occasion to supply a vacant
week or two with something by me, but that’s not worth mention¬
ing.

If you think fit you may, to prevent Fr. Linus’s slurring himself
in print with his wide conjecture, direct him to the scheme in my
second answer to P. Pardies, and signify (but not from me) that the
experiment, as it is represented, was tried in clear days, and the
prism placed close to the hole in the window, so that the light had no
room to diverge, and the coloured image made not parallel, (as in
his conjecture,) but transverse to the axis of the prism.

Your humble servant,

Is. Newton. 10

It would be wearisome and useless to give the details of this con¬
troversy which dragged along intermittently for many years. Only
enough need be told to show its unfortunate effect on Newton’s
character. Linus was evidently a typical example of the narrow¬
minded pedagogue who had grown conceited with the dictatorial
authority of the teacher in the school-room. Instead of accepting the
assurance that the experiments had been tried on cloudless days or of
repeating them himself, he published a letter in the Philosophical
Transactions accusing Newton of gross carelessness or of misrepre¬
senting the facts. No insinuation could have been more exasperating
to one, whose whole life proved his absolute and fearless intellectual
integrity. Stung to the quick he published his Considerations . n

10 Macclesfield, Vol. II, p. 368.—Newton had been invited to present before the Society
a series of experiments.

11 Phil. Trans., No., 121, p. 501.

9 °

ISAAC NEWTON

Newton to Oldenburg for the Royal Society

Cambridge, November 13, 1675.

Sir—When you showed me Mr. Line’s second letter, I remember I
told you that I thought an answer in writing would be insignificant,
because the dispute was not about any ratiocination, but my veracity
in relating an experiment, which he denies will succeed as it is de¬
scribed in my printed letters: for this is to be decided not by dis¬
course, but new trial of the experiment. What it is that imposes on
Mr. Line I cannot imagine: but I suspect he has not tried the experi¬
ment since he acquainted himself with my theory, but depends upon
his old notions, taken up before he had any hint given to observe the
figure of the coloured image. I shall desire him therefore, before
he returns any answer, to try it once more for his satisfaction. .. .

And he very properly concluded this rebuke by requesting that the
experiments may be repeated before the Royal Society, although Dr.
Hooke had already given testimony that all these experiments had
been verified by himself two or three years ago. Linus probably
never saw this answer, since “the epidemic catarrh, which hath
raged through so many countries, and taken away so many aged
persons, hath also overcome him.” The attack was continued by his
colleague, Gascoines, 12 who was incapable of experimenting him¬
self or of understanding what others had done. He merely asserted
dictatorially the superiority of the experienced Linus over a rash
youth who was conceitedly trying to upset the wisdom of his elders.
This was the time to drop the matter, and Newton would have done
so had he not been urged and nagged by Oldenburg to justify him¬
self.

Linus was succeeded in his professorship by Antoine Lucas who
proved to be an intelligent and open-minded opponent. He at once
heeded Newton’s plea to put the matter to the test of experience and
published a set of eight experiments of his own. He verified the ob¬
long form of the spectrum but found a very much less proportional
elongation. If Newton had not been out of all patience with the
controversy, he would easily have found that the discrepancy resulted
from the different dispersive powers of various kinds of glass. In that
^ase he would probably have discovered the simple remedy for
chromatic aberration later found by Chester More Hall, who com-

12 He is not to be confused with the mathematician, Gascoigne.

ARGUMENT ON THE NATURE OF LIGHT

bined a weak concave lens of high dispersive power with a stronger
convex lens of a low dispersion.

We may close this correspondence with the Belgian professors
by quoting one more letter.

Newton to Oldenburg

Sir,

18 November, 1676.

I promised to send you an answer to Mr. Lucas this next Tuesday,
but I find I shall scarce finish what I have designed, so as to get a
copy taken of it by that time, and therefore I beg your patience a
week longer. I see I have made myself a slave to philosophy, but if I
get free of Mr. Linus’s business I will resolutely bid adieu to it eter¬
nally, excepting what I do for my private satisfaction, or leave to
come out after me; for I see a man must either resolve to put out
nothing new, or to become a slave to defend it.

But to let this pass, I beg the favour of you to let your servant con¬
vey this, enclosed, to Mr. Boyle, I not knowing well how to direct it

to him. c . T

bir, I am

your humble servant,

I. N. 13

I cannot agree with those who dismiss the subject merely by say¬
ing that Newton’s critics were “silly” or jealous. This is too easy a
solution. The common experience in science has always been that
new ideas must submit themselves to the most searching criticism;
it is the glory of science that truth results from opposition. One has
only to compare the considerate treatment of Newton with the sav¬
age attacks on Galileo who persevered in the publication of his ideas
at the peril of his life. It is absurd to claim that Newton was opposed
by weak or vicious men; they were scholars of recognised ability
holding positions of responsibility. They were rightly supporting the
ideas of the greatest authorities of their day,—Kepler, Huygens, and,
above all others, the magic name of Descartes. How were they to
anticipate that this young and unknown man was an antagonist of
greater genius than all the authorities they cited?

Of Newton’s critics, the Liegeois professors can be ignored since
their criticism was unintelligent and irrelevant; of the others, Pardies

13 Macclesfield, Vol. II, p. 405,

ISAAC NEWTON

had been most open-minded, but the attitude of Huygens, the great¬
est living natural philosopher, was disheartening. Although im¬
pressed, at first, by the elegance and accuracy of Newton’s observa¬
tions, he finally opposed them because they did not agree with his
hypothesis of the vibrational nature of light. Biased' by his pre¬
conceived ideas, he shut his eyes to the value of the new experimental
evidence and became offended when he was sharply reprimanded for
not judging the facts on their own merit: “There were matter,” he
wrote to Oldenburg, “to answer them and to form new difficulties;
but seeing that he maintains his opinion with so much concern, I
list not to dispute.” It is only fair, however, to add that Huygens

and Newton later came to a mutual feeling of the highest respect and
regard. 14

It is impossible for us to understand the character of Newton or
the state of the physical sciences in the seventeenth century, without
referring at length to the life and work of Robert Hooke, or Hook,
as his name is indifferently spelled. What manner of man was he
whose personal opposition delayed the publication of Newton’s
Optics for thirty years and almost prevented the completion of the
Principia; whose bitter tongue confirmed Newton’s tendency to
secrecy and isolation, destroyed his early enthusiasm for the Royal
Society, and disgusted him with science?

Robert Hooke 15 was born in the Isle of Wight on the 18th of
July, 1635. Like Newton, he was at birth very infirm and weakly;
and for the first seven years his parents entertained but little hope of

is living to maturity. Like Newton, also, his scientific aptitude first
showed itself in his love and genius for inventing mechanical con¬
trivances. He was educated under the famous Dr. Busby of West¬
minster School, whose name in literature is synonymous with the great
efficacy of the rod and who boasted that sixteen of the living bish¬
ops had been birched with his “little rod”; later he entered Oxford
as a Servitor.

This University, at that time, offered far better opportunities for a
scientific training than were found by Newton at Cambridge. The
cause of this early cultivation of the new experimental philosophy at
Oxford came from the affiliation of a group of its Fellows with a
Philosophical Society in London which had been formed in 1645

14 Principia, Ed. 1803, p. xlix.

lo Most of the material for this sketch is taken from the life of Hooke prefixed to his
Posthumous Works, Edited by Richard Waller, Sec. R. S., and dedicated to Sir Isaac
Newton, Pres. R. S„ and to the Royal Society. London, 1705.

ARGUMENT ON THE NATURE OF LIGHT

and later developed into the powerful Royal Society. 10 This Oxford
group thus became almost an integral branch of the Royal Society
which was formally chartered by Charles II in 1660. It was the cus¬
tom for many years to communicate the more important papers to
the respective members of both Societies; and such experiments as
could not be carried on conveniently in London were made at Ox¬
ford, where meetings were held, more or less regularly, till 1690.

Hooke, even in his undergraduate days, attracted the attention of
these eminent Oxford scholars who recognised and encouraged his
inventive genius. He became the intimate friend and personal as¬
sistant of Boyle, who was not only the most distinguished man of
science in England but was incomparable in the purity of his ideals
and in his generous aid to the scientific work of others. As early
as 1658, or 9, we find the claim of Hooke in his manuscript notes,
that he had contrived and perfected the air-pump for Mr. Boyle
whose reputation largely depended on its use. He also invented and
made trials of flying machines and, when he found that they would
not succeed because of the weakness of our arms, he attempted to
overcome this defect by applying his mind to contrive a way to make
artificial muscles.

While we must discount many of Hooke’s claims, because a man
of such a feverish mental activity is certain to speculate on almost
every subject, and is too apt to confuse shrewd guesses with accom¬
plished results, yet we can be certain that he had shown his ex¬
perimental genius while an undergraduate, and had attracted the at¬
tention and support of influential men by the marvellous fertility of
his inventive powers. It is on record that a company was formed, at
that time, by Lord Brouncker, Robert Boyle, and Sir Robert Moray,
all of whom were prominent members of the new Royal Society, to
exploit the inventions of Hooke and, especially, his application of a
coiled spring to drive clocks and pocket watches.

He was, however, soon called away from Oxford to a broader
field of opportunity. On the 12th of November, 1662, he was pro¬
posed by Sir Robert Moray as willing to act in the capacity of Curator
of the Royal Society, two years after it had received its Charter. He
agreed to the astounding proposition recorded in its Journal-book,
“to furnish the Society every day they meet [once a week] with three
or four considerable experiments, expecting no recompence till the
Society get a stock enabling them to give it.” No place could have

16 Cf. Chapter XIII for the history of these two societies.

ISAAC NEWTON

offered a better opportunity for a man of his temperament; he con¬
tinued to hold this position until his death and he laid the foundation
for the future usefulness and distinction of the Society. “The Jour¬
nal-books record the trial by him of several hundreds of experiments,
mostly new, by which ‘facts multiplied, leading phenomena became
prominent, laws began to emerge, and generalisations to commence.’
Waller, in his Life of Hooke, states that it was ‘observed by several
persons, that whatever apparatus he contrived, for exhibiting any ex¬
periments before the Royal Society, it was performed with the least
embarrassment, clearly, and evidently.’ ” 17

In addition to the unremitting toil necessary to his position as
official experimenter, he was also energetic in collecting curiosities
for the cabinet. We have evidence of his industry from Cosimo III,
Grand Duke of Tuscany, who visited the Society in 1669: “The
cabinet, which is under the care of Dr. Hooke, a man of genius,—is
full of the greatest rarities,—the Academicians contribute everything
of value which comes into their hands. Amongst these curiosities,
the most remarkable are: an ostrich, whose young were always born
alive; an herb which grew in the stomach of a thrush; and the skin
of a moor, tanned, with the beard and hair white: but more worthy
of observation than all the rest, is a clock, whose movements are de¬
rived from the vicinity of a lodestone, and it is so adjusted as to dis¬
cover the distance of countries at sea by the longitude.” 18 The exhibits
are enumerated in order to show that science was still in the period
of credulous acceptance of the marvellous.

After the great fire of 1666, the advice of the Society was sought for
plans to rebuild London. The esteem in which Hooke was held, at
the early age of thirty-one, is evident from the fact that he was ap¬
pointed City Surveyor and made a model for rebuilding the city. But
his plan was not adopted because private interests blocked his attempt
to realign and widen important thoroughfares. 19

In Hooke, we have a striking illustration of a great intellect housed
in a wretched bodily tenement and showing the contrast of an es¬
sentially noble character in large matters with an irritable, suspicious,
and cynical temperament, in the familiar affairs of life. His col-

17 Weld, Hist. Roy. Soc., Vol. I, p. 138. 18 ibid., Vol. I, p. 219.

19 According to Waller, it was as one of the city surveyors that Hooke acquired the
greater part of his estate: “He might by this place acquire a considerable estate, every
particular person being in haste to have his concerns expedited; so that, as I have been
inform’d, he had no rest early and late from persons soliciting to have their grounds set
out, which, without any fraud or injustice, deserv’d a due recompense in so fatiguing an
employ.” Weld, Vol. I, p. 362.

ARGUMENT ON THE NATURE OF LIGHT

leagues disliked and feared him for his saturnine temper and his
caustic tongue. He was notorious for his criticisms of their work and
for his insinuations that they had stolen the fruits of his labour. He
was morbidly sensitive about his physical appearance which was frail
and undersized almost to the degree of a deformity. Yet in spite of
handicaps of appearance and temper, he won the admiration of the
world by his genius and intellectual industry. Although he suffered
persistently from excruciating headaches and devastating illnesses,
he never relaxed from his arduous labours which embraced the en¬
tire field of science. “He was,” says his biographer Waller, “of an
active, restless, indefatigable genius, even almost to the last; and al¬
ways slept little, to his death, seldom going to sleep till two, three,
or four o’clock in the morning, and seldomer to bed, oftener con¬
tinuing his studies all night, and taking a short nap in the day. His
temper was melancholy, mistrustful, and jealous, which more in¬
creased upon him with his years.” 20 Like his great contemporaries,
Boyle and Newton, he was deeply and sincerely religious and looked
upon his scientific work as primarily important in disclosing the
purpose of God towards man. He died on the 3rd of March, 1702/3,
after a lingering and distressing illness. His suffering and infirmities,
during the latter years of his life, were so great that one of his
biographers speaks of him as “living a dying life.”

The duties imposed on Hooke by his official position in the Society,
and his impatient temperament, prevented him from the sustained
labour necessary for connected and large work. He published only
one connected treatise which, under the title of the Micrographia,
appeared in 1665, three years after he went to London. The main
part of this work is devoted to descriptions and engravings of minute
bodies as viewed under a home-made microscope. It shows positively
that he had a clear grasp of the combinations and principles of lenses
to be used in making microscopes and telescopes. He also includes
his experiments on various phenomena of light, of which those on
the colours produced in thin films are the most important. In this
work, he was influenced by Boyle who had also investigated the sub¬
ject. Here, also, is to be found the development of his hypothesis of
the vibratory nature of light to explain his experimental discoveries.

Although Newton referred only once, and then casually, to having
read the Micrographia, an examination of his work shows conclu¬
sively that he was greatly influenced by Hooke’s experiments on thin

20 Weld, Vol. I, p. 359.

9 6

ISAAC NEWTON

films and on diffraction. Newton rarely mentioned any of the
sources from which he drew the inspiration for his work. In the
Optics, for instance, he merely stated that Grimaldi had discovered
a curious bending of light into the geometric shadow and gave no
credit to Hooke although he had made and published many experi¬
ments in the subject. It was an unavoidable misfortune that Hooke’s
reputation should suffer an eclipse, and that Newton’s incomparable
glory should dim his rival’s lesser achievements. But it is inexcusa¬
ble that Newton’s eulogists, amongst whom must be included
Brewster, should have felt that they could add to the prestige of their
hero by slurring the character and achievements of such a competitor.
The tradition they have handed down to us that Hooke’s hypo¬
thetical ideas on light were puerile and foolish is quite false, for he
was in advance of his age and had almost grasped the idea of the
wave theory of light.

We should rather learn to look upon Newton, not only as a con¬
summate creative genius but also as a profound scholar who had
read widely and had assimilated the work of others. His treatise on
Optics may, by its omission of citation of others’ work, give the im¬
pression that he conceived his experiments and ideas entirely from his
own meditations; but his early papers in the Philosophical Transac¬
tions, and especially the one in which he vindicated himself against
Hooke’s charge of plagiarism, and surveyed the history of the hypoth¬
eses of light, prove conclusively, to the unbiased reader, that Newton
was conversant with the history of science from ancient to con¬
temporaneous times and that he had borrowed freely from all
sources. Like Shakespeare, he found his material wherever it was to
be had, and like Shakespeare he moulded it and built out of it an
edifice more beautiful than its original discoverers could have
imagined. But there is this difference between them; Shakespeare,
from the character of his work, was not called upon to acknowledge
his indebtedness to others, but Newton was placed in the position
many times, particularly in his controversies with Hooke, Leibniz,
and Flamsteed, when honour, or at least generosity, required him
to be open and explicit in giving credit for their work. Too often,
he remained silent or crushed his opponent with the weight of his
reputation.

We could scarcely imagine two men more certain to disagree in
personal and intellectual relations than Hooke and Newton. Both

ARGUMENT ON THE NATURE OF LIGHT

were temperamentally suspicious and jealous; both were impatient
of opposition and sensitive to criticism. Newton, animated with a
pure love of truth, never permitted himself to swerve from the high
standard of his intellectual integrity. But he was not so guided in
his personal standards; he met criticism by a covert attack on his
critics or weakly threatened to abandon scientific work, lest by being
induced to divulge his thoughts to an ungrateful world he should be
disturbed in the pursuit of his private meditations. Hooke, on the
other hand, blazed out into wrathful explosions, bitter recriminations,
and accusations that his ideas had been stolen.

Also their environment would, of itself, keep them apart. Newton,
living isolated and undisturbed, concentrated on a few subjects and,
having seized on a few fundamental facts, never relaxed till he had
wrung from them their deepest meaning. Lie made public a very
small body of work, but each portion was an imperishable monu¬
ment to his genius. Whereas Hooke, distracted by executive duties
and required to complete three or four hurried experiments weekly,
left a mass of undigested and scattered observations which have been
swallowed up in the course of later and more accurate experimenta¬
tion. He suffered from the exasperating experience of seeing his
fertile hints developed by others and contributory to their fame. His
work on light, which forms the bulk of his Micrographia and Post¬
humous Papers, is the only subject which shows any consecutive de¬
velopment, and he evidently regarded it as his chief contribution to
science. And yet, although his hypothesis as to the nature of light
was in advance of current ideas, history has characterised it as puerile
in comparison with the work of Huygens and Newton.

Hooke, like Newton, was thoroughly in sympathy with the ambi¬
tion of Descartes to substitute a purely mechanical universe, based on
the experimental laws of matter and motion, for the teleological
system of Aristotle. Both of them believed that the purpose of
science was to discover and classify phenomena, and had a strong
leaning to the application of science to practical problems; but they
were also tinctured with the mediaeval belief that God had created
and continued to guide the world according to His will. The new
discoveries in astronomy, mechanics, and light may have shaken
their belief in the miraculous, and have substituted the idea that God,
as an omnipotent geometer, had fashioned a universal machine sub¬
ject to rigorous mechanical laws; but they also firmly believed that

ISAAC NEWTON

God had endowed us with “an inward sentiment of knowledge”
capable of understanding and exposing His plan and purpose, in
order that, from a knowledge of His work, we should know Him.

Although Huygens, Hooke, and Pardies, the three principal op¬
ponents of Newton, were men of widely different temperament and
achievement, they were all proponents of the Cartesian philosophy.
We can easily imagine the general attitude of the scholarly world;
on the one side, there was a young, and unknown, man who had
proposed a revolutionary method based on a few simple experiments;
on the other side was entrenched the dogmatic authority of accepted
procedure, buttressed by the glittering and grandiose cosmical system
of Descartes. Can we doubt to which side the rank and file leaned ?
It was not until Newton had proved himself a greater genius than
Descartes that the world accepted his leadership. And then, such is
the irony of fate, his basic definition of the limitations of the scientific
method was more or less ignored or forgotten; while his merely
tentative queries about the nature of the universe were seized upon,
that out of them might be erected a new and even more glittering
cosmogony than that of Descartes.

Descartes, as has been noted previously, had included in his cos¬
mical system a purely imaginative explanation of the nature of light
and colour unsupported by any experimental evidence. He merely
asserted that light, in essence, was a pressure transmitted instanta¬
neously through space from a cosmic vortex. The action of this pres¬
sure on matter was to give a translational motion to certain particles
which he first created and then named “light globules.” The impact
of these globules on the retina produced the sensation of whiteness;
but if, in their passage through matter, the globules had also acquired
a rotatory motion, then we experienced a sensation of colour.

The only possible value of this hypothesis was the attempt to ex¬
plain light in terms of mechanical ideas. But Hooke, following up
some observations of Boyle, approached the subject from its experi¬
mental side and had made a large number of observations on the
colours produced by light reflected from transparent films of mica,
soap bubbles, etc. By a masterly analysis of the facts, he recognised
that the succession of colours which he observed was produced by the
combination of a beam of light reflected from the upper surface of
the film with a second beam which had penetrated the film and had
been reflected from its lower surface. He then saw that Descartes’s
hypothesis, of the conversion of light (whiteness) into colour by

ARGUMENT ON THE NATURE OF LIGHT

adding a rotatory motion to the linear propagation of globules, was
fundamentally at fault and untenable. His conclusion should be
given in his own quaint language: “Here we have all kinds of
colours generated in a pellucid body, where there is properly no
such refraction as Descartes supposes his globules to acquire a ver-
ticity by; For in the plane and even plates it is manifest, that the sec¬
ond refraction does regulate and restore the supposed turbinated
globules unto their former uniform motion. This experiment will
prove such a one as our thrice excellent Verulam calls experi-
mentum crucis.

Hooke had discovered the fundamental phenomenon of the inter¬
ference of light, and had noted the correct succession of colours. But
he failed to take the final, and decisive, step of submitting his
observations to quantitative measurement which Newton happily ac¬
complished by observing the colours produced in the measured film
of air between a glass plate and a superimposed plano-convex lens.
And by that failure, the credit of the whole discovery passed to New¬
ton.

As a result of his observations, Hooke then drew three conclusions:
first, the parts of all fiery burning bodies are in motion ; secondly, the
motion is exceeding quick and vibrative; thirdly, it is a very short
vibrative motion. This first explanation was later modified to con¬
form to the ideas of Newton, for in his lectures on light, delivered in
1680, he shifted to the idea that light is a corporeal substance, a kind
of uncompressible fluid capable of motion like all other bodies. This
motion of the “light substance” is propagated in the medium either
by waves of motion spreading out in rings or else by the extrusion of
the part of the fluid medium of light that lies between the solid par¬
ticles of the shining body, like water from a sponge. It seemed in
some cases, according to him, to be the one way; and in other cases,
the other way. 22

In their general ideas, Hooke and Newton were never far apart.
They both hoped to express the phenomena of light either as the
action of a substance or as a vibratory motion, and each influenced
the other’s ideas. They split on the question of what constitutes a
primary colour and it will not be difficult to show that the cause of
their difference arose only from their incompatible definitions of
colour.

Hooke had discovered the psychological effect that the mixture of

21 Micrographia, p. 54. 22 Hooke, Posthumous Papers, p. 115.

100

ISAAC NEWTON

two complementary colours, such as scarlet and blue, produced a
sensation of white which could not be distinguished from sun-light.
He therefore assumed them to be the only primary colours, and that
all others are mixtures of these two with light and darkness. He
then, without any basis of fact, followed the fashion and formulated
a hypothetical cause for colour. He says: “The phenomenon of
colour depends on the obliquity of the orbicular pulse [i.e., the wave-
front] to the lines of radiation. The ray which constitutes the scar¬
let has its inner parts, namely those which are next to the middle of
the luminous body, precedent to the outermost which are contiguous
to the dark and unradiating sky. And that the ray, which gives a
blue, has its outward part precedent to the pulse from the inner¬
most part.” 23

Just here lies the evidence of the genius which separated Newton
from his competitors. He, in the first place, refused to make an
hypothetical explanation of colour and, in the second place, he re¬
fused to adopt the psychologic or subjective sensation of colour as a
criterion for physical or objective phenomena of light. To him, a
primary colour was one which had a definite angle of refrangibility,
whatever sensation of colour it might cause, and could not be de¬
composed by passing it through a prism. The eye thus is merely a
recording instrument for certain phenomena of light and may not
be sensitive to others which can properly be classed as invisible light.
To instance only one example: we know that radiation is not limited
by the visible spectrum; beyond the blue end invisible energy can be
detected by a photographic plate and beyond the red end by a ther¬
mometer and, except for their inability to affect the eye, such radia¬
tions are identical with those which are visible. And in fact phenom¬
ena pertaining to visible light are frequently observed, and accurately
measured, by thermometers or electrical instruments whose responses
can be determined by the sense of touch. While our contact with the
external world is necessarily by our sensations, the physicist has suc¬
cessfully discarded the sensation immediately concerned for one
which is less liable to be thus confused. While for phenomena of
light the eye may often be used, an instrument is interposed whose
record will not depend on the same class of phenomena. The “white”
which was created by Hooke’s primary red and blue colours was not
by Newton’s criterion equivalent to the “white” which could be
spread out into the indefinite number of colours of the continuous

23 Micrographia, p. 59.

ARGUMENT ON THE NATURE OF LIGHT

IOI

spectrum; each of these constituents of the rainbow was therefore a
primary colour. This may seem to be a trifling difference but it in¬
volves the essential problem of what constitutes the scientific method.

While physicists have more and more discarded the psychologic
sensations as criteria and have, as far as possible, formulated objective
laws, they still confuse subjective sight and objective light, or radia¬
tion; in text-books they discuss colour as if it were an objective reality
and yet explain it subjectively by the supposition of a nerve reaction
to three primary colours, altogether ignoring the fact that in another
portion of the book they define a primary colour as any one of the
indefinite number of lines in a continuous spectrum. On the other
hand, psychologists endeavour to measure subjective phenomena of
sight with physical instruments as though they were independent of
the sensation of vision. Neither realises that there is no common
ground of fact or theory. To the physicist, the problem ends when
light energy is physically absorbed by the retina; for the psychologist
the problem begins with that absorption. What happens in the in¬
terval between the physical absorption of energy and the mental
translation into vision is a process to which science can give no clue.
The phenomena of sight and light form two irreducible and incom¬
mensurable categories.

As another example of the gulf between psychology and physics,
I may instance the phenomenon of after-images. If the eye becomes
fatigued by steady gazing at an intense red light and is then closed,
there appears to the mind the subjective image of the same object
changed to the colour complementary to red. However the psychol¬
ogists may attempt to explain such a phenomenon, their explanation
will not fall under any known physical law of optics. The variation
they are studying occurs not in the active agent but in the receiving
instrument which records an action of its own contrivance.

An even more convincing illustration may be given of the funda¬
mental difference between the points of view of the psychologist and
the physicist. Let us consider the well-known phenomenon of
colour blindness which prevents certain persons from distinguishing
between redness and greenness. The assertion by the psychologists,
derived from the sense perception of sight, that there are the two
qualities of redness and greenness is one which must always remain
a pure matter of opinion to be decided by the fact that the majority of
people possess the ability to make such a distinction. Because the ma¬
jority is large, the minority are content to conform to their opinion

102

ISAAC NEWTON

and to confess an abnormality of vision although they have no possibil¬
ity of perceiving the difference. It would not be difficult to imagine
all human beings to be thus colour blind. Granted such a condition,
the possibility of distinguishing between these two colours, visually or
psychologically, could never have arisen; yet the physicist with a
prism would have no difficulty in distinguishing them by their
specific refrangibilities.

I am not one who indulges in the vain fancy of imagining what
the world would have been without intelligent and self-conscious
beings like ourselves to observe and interpret its phenomena, or of
speculating whether it could be said to exist independently of a
sentient organic being; I look upon such pictures (so often given us
by evolutionists and metaphysicians) as idle dreams and impossible
speculations made by one who first of all postulates the state of non¬
existence of himself. But it is possible to imagine a world like ours
except for the fact that no organic being on it possessed the sensation
of sight, in the language of evolution, that the eye had never de¬
veloped. Would it be an exaggeration to say that the idea of colour
would never have been conceived and that there would have been no
phenomena of light so far as either psychology or physiology is con¬
cerned? But there could still be an objective science of light radiation,
because many of the phenomena, which we, possessed of vision, now
fuse with the sensation of colour and light, could be discovered by
the physicist by other means even if the whole race of men had al¬
ways been blind. I am, of course, merely stating the old and trite
question; is there a sound if a tree falls in a forest when there is no
one near enough to hear it ? To the physicist, a sound is only a par¬
ticular form of vibratory motion in the air, or other medium, which
can be detected and measured by any suitable apparatus whether or
not it be audible; to the psychologist, audibility is the essence of such
radiation. Are we not justified in agreeing with Newton that the
sensation of colour is not a criterion in establishing the physical laws
of light ? To avoid confusion of thought, all theories of colour sensa¬
tion should be omitted from the science of physics. There are no
primary colours, except in the sense that there are primary sound-
tones. Any colour which cannot be decomposed by Newton’s
criterion of the laws of refrangibility is a primary colour, just as a
tone is acoustically primary if it is due to a simple harmonic motion.
Newton has, once for all, enunciated the fundamental difference be-

ARGUMENT ON THE NATURE OF LIGHT

103

tween physics and all the biological sciences,—between objective and
subjective phenomena.

The controversy between Hooke and Newton is thus funda¬
mentally important, since it, for the first time, raised the issue be¬
tween the hypothetical and the theoretical methods. It is fortunate
that, on the whole, the Newtonian method has prevailed and has
made possible the growth of physics into the most nearly exact of the
sciences. But it is unfortunate that the hypothetical method in
science still confuses the issue, and prevents us from distinguishing
between the objective and subjective worlds,—between science and
humanism.

After this long digression, we can discuss Newton’s attack on
hypothetical reasoning with the better hope of clearing up some of
the misconceptions which still persist in regard to his ideas. His
conviction, that the scientific method is dependent on an intuitive be¬
lief in the objective reality of natural phenomena and is limited to
mathematical formulation of laws derived from their observation
and classification, was undoubtedly temperamental, as it clearly
showed itself in his earliest years.

The source of the opposition to Newton, as has been previously
noted, sprang from the dogmatic acceptance of Descartes’s cosmical
hypothesis. While Newton may have been too sensitive to any crit¬
icism, he was morbidly so, when the opposition was supported by the
bare authority of a great name. I have little doubt that his persistent
depreciation of even Descartes’s solid scientific work may be assigned
to this cause, and is the answer to Biot’s surprise when, in his essay
on Newton, he comments: “It is singular, however, that Newton, in
his writings, has never mentioned Descartes favourably; and, on
more than one occasion, has treated him with injustice. Particularly
in his Optics, where he attributes the discovery of the true theory of
the rainbow to Antonius de Dominis, leaving to Descartes only the
merit of having 'mended the explication of the exterior bow’; and yet
every impartial reader, who refers to the original works, will see that
the theory of Descartes is exact and complete.—And the book of
Dominis contains absolutely nothing but explications entirely vague,
without any calculation or real result.”

Newton not only grasped the fundamental principle of the scien¬
tific method and defined the limits beyond which exact sciences can¬
not go, but he also warned men of science against the confusion of
thought which results from the careless use of words. From the be-

ISAAC NEWTON

104

ginning he recognised that the gravamen of the criticism was directed
against deductions made from his observations rather than against
the facts themselves. He also saw clearly that the source of disagree¬
ment in scientific arguments is often to be found in laxity of ex¬
pression. Thus he insisted on the fundamental distinction between
hypotheses and theories: “As to the Rev. Father’s [Pardies] calling
our doctrine an hypothesis, I believe it only proceeded from his us¬
ing the word which first occurred to him, as a practice has arisen of
calling by the name hypothesis whatever is explained in philosophy:
and the reason for my taking exception to the word, was to prevent
the prevalence of a term, which might be prejudicial to true philos¬
ophy.” It cannot be denied that there is a real distinction between
ideas about the objective world which are deduced from phenomena
by experiment, or are verifiable by experiment, and ideas which are
not; and it would be an invaluable aid to clear thinking if we should
emphasise this difference by preserving the distinction between an
. hypothesis and a theory ’ which Newton introduced. If the warn-
lAi g against looseness or diction was needed in Newton’s day, when
learned men used Latin in familiar conversation and employed a
nicer discrimination in English, it is far more necessary today when
our conversation is slovenly, and men of science as a class are igno¬
rant of Latin, and disdainful of literary training. If the student of
science spent a little less time in the laboratory, and more time in
learning a coirect use of his native tongue and greater care in ex¬
pressing his thoughts accurately, the controversial literature of science
would be greatly reduced in bulk, and the world at large could dis¬
tinguish between the solid ground of scientific truth and the vagaries
of pseudo-science.

The young Newton began his long polemic against “hypotheses”
in the mild form of expressing his preference for the experimental
method. Thus he wrote to Pardies: “Give me leave, Sir, to insinuate
that I cannot think it effectual for determining truth, to examine the
several ways by which phenomena may be explained, unless where
there can be a perfect enumeration of all these ways. You know that
the proper method for enquiring after the properties of things, is to
deduce them from experiments.” 24 And again: “Hypotheses should
be subservient only, in explaining the properties of things, but not as¬
sumed in determining them; unless so far as they may furnish ex¬
periments.” 25

24 Phil. Trans., No. 85, p. 5004.

25 Ibid., No. 85, p. 5014.

ARGUMENT ON THE NATURE OF LIGHT

105

It was only when he found that even such critics as Huygens and
Hooke would not accept his experiments on their own merit, but
judged them adversely because of a disagreement with their psycho¬
logic hypothesis of two primary colours,—it was then that he stiffened
in his opposition to including imaginative concepts of the objective
world in the scientific method. He rebuked Hooke in print. First,
he sarcastically declared that he could imagine many hypotheses
which will explain all the known experimental facts as satisfactorily
as does Hooke’s hypothesis. Then he showed that Hooke’s hypoth¬
esis will not really explain the observations of either of them; and
lastly, he dismissed the subject as unimportant, after pointing out cer¬
tain fundamental objections to a wave theory of light. “It is true that
from my theory I argue the corporeity of light; but I do it without
any absolute positiveness... . But I knew that the properties which I
declare of light, were in some measure capable of being explicated,
not only by that, but by many other mechanical hypotheses. And
therefore I chose to decline them all and to speak of light in general
terms. . . . You see therefore, how much it is beside the business in
hand to dispute about hypotheses .” 26

Newton had encountered a common failing from which men of
science are not exempt; the hypothetical children of the mind are
objects of such tender solicitude to their parents, that they are more
anxious to safeguard them than to examine impersonally the truth
of experimental facts. He came to the conclusion that his contem¬
poraries were absolutely unable to understand the fundamental dif¬
ference between hypothesis and experimental law. As a result of
this conviction, painfully borne in on him by altercation after alterca¬
tion, he determined to discard the hypothetical method altogether in
the Principia and in his treatise on Optics. The classic statement of
this determination is given in the General Scholium at the end of the
Principia: “Hitherto I have not been able to discover the cause of
those properties of gravity from phenomena, and I frame no hy¬
potheses, hypotheses non jingo; for whatever is not deduced from
the phenomena is to be called an hypothesis; and hypotheses,
whether metaphysical or physical, whether of occult qualities or
mechanical, have no place in experimental philosophy. In this phi¬
losophy particular propositions are inferred from the phenomena,
and afterwards rendered general by induction. Thus it was that the
impenetrability, the mobility, and the impulsive force of bodies, and

26 Phil. Trans., No, 88, p. 5084.

io6

ISAAC NEWTON

the laws of motion and of gravitation, were discovered. And to us
it is enough that gravity does really exist, and act according to the
laws which we have explained, and abundantly serves to account for
all the motions of the celestial bodies, and of our sea.” 27

While Newton excluded hypothesis from the field of science, he,
as is the habit of anyone with imagination, indulged in much private
speculation as to the causes of phenomena and the nature of the
physical universe. His excellence lay in the fact that his mind was so
disciplined that, while such fancies might delight his power of in¬
vention and spur him to continued effort, he never confused them
with the permanent acquisition of knowledge which follows from a
careful investigation of phenomena and natural laws.

To turn from a discussion of general differences between the two
philosophers to the specific cause of their mutual hostility, we should
remember that Hooke had been appointed a member of a committee
of the Royal Society to consider the new work of Newton. His re¬
port was appreciative of Newton’s experimental work, but in it he
had the bad taste to advise him, as a novice, to continue his useful
labour of improving the telescope and to leave the general field of
experimental light to those who had perfected a thoroughly satis¬
factory hypothesis. He also indulged in his customary and obnoxious
habit of claiming that most of the discoveries had been made by
himself. He, lastly, brushed aside Newton’s disclaimer of neither
proposing, nor needing, an hypothesis since he had, on the contrary,
really advanced the notion that “light is a body, and that as many
colours or degrees as there may be, so many bodies there may be; all
which compounded together would make white.”

Oldenburg, the Secretary, promptly reported to Newton what had
occurred in the Council of the Society, and urged him to defend
himself against what he termed a secret attack. The motive for the
advice may have been a sincere interest in his friend’s welfare, but
it was undoubtedly influenced by the evident jealousy which existed
between himself and Hooke. As a consequence of his own antipathy,
he exaggerated the Curator’s irascibility and gave the impression that
matters were worse than they actually were. This time he succeeded,
and Newton prepared a long letter for publication in which he
vindicated his own work and criticised in detail Hooke’s hypothesis
and his unjust attitude.

27 Andrew Motte’s translation of the Principia, Vol. II, p. 314, London, 1803.

ARGUMENT ON THE NATURE OF LIGHT

107

In this memoir 28 Newton acknowledged that, from his theory, he
had argued the corporeity of light but did so without any absolute
positiveness. He had foreseen that his discoveries were explicable in
some measure by that supposition, but as they were equally well
explained by vibrations and by many other mechanical hypotheses,
he chose to decline them all and to speak of light only in the most
general terms. Why, he asked, does Hooke become so agitated
against such an hypothesis, since a belief in vibrations as a cause of
colour is as applicable to it as to his own?

He thus admitted that he had vaguely defined light as some thing
or some power propagated in straight lines. And he had proposed a
corpuscular hypothesis, if one could call it by such a name, because
he believed it had a close affinity to Hooke’s own hypothesis of
vibratory motion and not as a substitute to it. Unfortunately, how¬
ever, he had spoken loosely of colours,—a term in common use for
rays of light,—as if they were objective qualities of light instead of
the subjective sensation excited in our minds by specific variations of
a light substance or of its mechanical motion. Such light corpuscles,
when they impinge on a reflecting or refracting material surface,
would excite vibrations in the aether “as stones do in water when
thrown into it,” and we may assume these vibrations to be of various
wave lengths according to the sizes and velocities of the corpuscles
causing them. How these different vibrations account for reflection
and refraction, heat, phenomena of colours in thin films, vision,
colours of bodies, etc., “I shall leave to their consideration, who may
think it worth their endeavour to apply their hypothesis to the
solution of the phenomena.”

Newton next stated Hooke’s hypothesis as he understood it: “The
parts of bodies, when briskly agitated, do excite vibrations in the
aether, which are propagated every way from those bodies in straight
lines, and cause a sensation of light by beating and dashing against
the bottom of the eye, something after the manner that vibrations in
the air cause a sensation of sound by beating against the organs of
hearing.” This, he claimed, can mean only that the agitated parts
of luminous bodies differ in shape, size, and motion, thus producing
vibrations of various depths and sizes in the aether. A mixture of
these vibrations excites a sensation of whiteness, whether by two
complementary colours or by the whole spectrum. But, if the dif¬
ferent vibrations are sorted out by any means, such as by a prism,

28 Phil. Trans., No. 88, p. 5084, July 11, 1671.

iq8

ISAAC NEWTON

the largest beget the sensation of a red colour; the least, or shortest,
a violet; and similarly for the intermediate colours of the spectrum.
This seemed to Newton a necessary corollary to Hooke’s hypothesis
and he should therefore welcome the new discovery of selective
refrangibility and of decomposition of white light into an indefinite
number of primary rays, or of primary colours if we translate the
objective phenomena into their subjective sensation of vision.

Newton finally gives his reasons why he believes in a corporeal,
or corpuscular, nature of light to which must be added the ancillary
effect of aethereal vibrations. It was his settled conviction that the
rectilinear propagation of light in vacuo cannot be explained except
by the hypothesis of corpuscles moving with a great velocity in
straight lines; it is impossible “that waves or vibrations in any fluid
can, like the rays of light, be propagated in straight lines, without a
continual and very extravagant spreading and bending every way
into the quiescent medium, where they are terminated by it.” Ac¬
cording to the knowledge of the day, he was correct. From observa¬
tion of waves in water and of sound in air, he knew that waves do
not progress in straight lines; water waves bend around an obstacle,
and sound waves encroach deeply into the shadow; but the shadow
cast by an obstacle placed in a beam of light was believed to be
bounded by geometrically straight lines drawn from a point source
to a screen. To be sure, the obscure phenomenon of diffraction had
been discovered by Grimaldi, but no one then knew that it could be
explained by a similar bending of rays of light. Before the diffrac¬
tion of light, as an evidence of the bending of light rays into a
shadow, could be incorporated into a wave theory, Huygen’s cele¬
brated mathematical theorem of the rectilinear propagation of waves,
combined with the principle of secondary point sources and inter¬
ference, had to be developed. Even this support of a wave theory
left its author’s hands defective and more than a century passed be¬
fore a rigorous solution of the problem was discovered. Even now
an insuperable objection to a pure wave hypothesis persists; an
aethereal medium must be imagined whose mechanical properties
are absolutely contrary to our experience of material substances,—
a fluid so fictitious, and so impossible of visualisation, that it became
a burden, instead of an aid, to science.

Thus Newton made no objection to the hypothesis that light is,
in a general way, either moving corpuscles or aethereal waves. For,

ARGUMENT ON THE NATURE OF LIGHT

109

in fact, if one attempts to define all physical phenomena in terms of
mechanical action, light must be one or the other, or a combination
of both, since they are the only known methods by which mechanical
energy can be transmitted through space. So he pointed out that his
experimental results could be taken as a support to Hooke’s, or any
other, hypothesis of a mechanical nature. But the habit of giving
specific properties to an occult corpuscle or to an occult aether was
abhorrent to him. From these general considerations, he then turned
on his critic and, in a few sentences, demolished Hooke’s particular
hypothesis that there are only two colours, red and blue, which are
themselves explained “by the splitting and rarefying of aethereal
pulses,”—an explanation that his own experiments had made futile.
“If,” he concluded, “I would proceed to examine these his explica¬
tions, I think it would be no difficult matter to show that they are
not only insufficient, but in some respects, to me, at least, unintel¬
ligible.”

We can easily imagine that Newton’s vindication of his own ideas,
and crushing counter-attack on Hooke’s cherished hypothesis, pro¬
duced a profound effect on the abler members of the Royal Society.
We can, also, be sure that it vastly increased Hooke’s irritable temper.
From the correspondence between Oldenburg and Newton, we are
certain that Hooke used the advantage of his constant attendance
and official influence to prejudice the members against the absent
Cambridge professor by accusing him of taking from the Micro -
graphia whatever was of any real value in his work. Newton en¬
dured these attacks for three years and then answered them only in
a personal letter to Oldenburg which he forbade to be published;
but, it is altogether probable that his correspondent showed it to
some, at least, of his fellow-members.

From the following entries in the Journal-book of the Society we
can appreciate how far Hooke had progressed in his opposition and
why Newton finally broke his silence to vindicate himself in such a
crushing manner.

“On December 9, 1675, Newton sent a manuscript, giving the
principal phenomena connected with the colours produced in thin
plates by refraction.”

On December 16, 1675: “The sequel of his [Newton’s] hypothesis,
which was began [sic] to be read the last day, was read to the end. To
which Mr. Hook said, that the main of it was contained in his

ISAAC NEWTON

Micrographia, which Mr. Newton, in some particulars, had only
carried further.” This communication was not published and pre¬
sumably because of Hooke’s objection.

At the meeting of January 20, 1675/6, Newton’s letter to Olden¬
burg of 21 December, 1675, was read in which he sharply criticised
Hooke.

The portion of a letter to Oldenburg, dated 10 January, 1675/6,
which refers to Hooke is as follows: 29

“I am obliged to you, Sir, for your candour, in acquainting me
with Mr. Hook’s insinuations. It is but a reasonable piece of justice,
I should have an opportunity to vindicate myself from what may be
undeservedly cast on me; and therefore, since you have been pleased
to be my representative there, and I have no means of knowing what
is done but by you, I hope you will continue that equitable candour;
though I think the present business of no great moment as to me,
not imagining that the Royal Society are to be imposed on in a thing
so plain, or that Mr. Hook himself will persist in a mistake, when
he hears the difference stated. The only thing I said he could pre¬
tend taken from his hypothesis, was the disposition of aether to
vibrate; and yet whilst he grasps at all, he is likely to fall short of
this too. That aethereal vibrations are light, is his; but that aether
may vibrate (which is all, I suppose) is to be had from a higher foun¬
tain: for that aether is a finer degree of air, and air a vibrating me¬
dium, are old notions, and the principles I go upon. I desire Mr.
Hook to shew me, therefore, I say not only the sum of the hypothesis
I wrote, which is his insinuation, but only part of it taken out of his
Micrographia; but then I expect too, that he instance in what is his
own. It is most likely he will pretend, I had from him the applica¬
tion of vibrations to the solution of the phenomena of thin plates:
and yet all the use I make of vibrations, is, to strengthen or weaken
the reflecting power of the aetheral superficies; which is so far from
being in his Micrographia, that the last spring, when I told him of
the reflecting power of the aethereal superficies, he took it for a new
notion; having till then supposed light to be reflected by the parts of
gross bodies. To the things that he has from Descartes, pray add
this, that the parts of solid bodies have a vibrating motion, least he
should say I had from him what I say about heat. And his having
from Descartes the reduction of all colours to two, you may, if need

29 A part of this letter referring to Linus’s criticisms was published in the Phil. Trans.,
but the portion which I have given was suppressed. The whole letter is printed by Horsley*
Opera Omnia, Vol. IV, p. 355.

ARGUMENT ON THE NATURE OF LIGHT

be, explain further for me thus. That as Descartes puts every globu¬
lus to be urged forward on one side by the illuminated medium, and
impeded on the other by the dark one; so Mr. Hook puts every
vibration to be promoted at one end, and retarded at the other by
those mediums; and thence both alike derive two modifications of
light, on the two sides of the refracted beam, for the production of
all colours.”

Although Newton sent no more communications to the Society
after 1675 on the subject of light, he continued his experimental
work, extending his knowledge of refraction, colours in thin plates,
diffraction, and the new phenomenon of double refraction produced
by crystals of Iceland spar. He also pondered deeply on the nature
of light. While he still maintained his early conviction that light,
itself, was material, yet he became more and more influenced by the
ideas of Huygens and Hooke, whose experimental ingenuity he fully
appreciated and whose hypothesis of vibrations had steadily pro¬
gressed in public estimation. So, when he published his Treatise on
Optics many years later, he limited the body of his work to a discus¬
sion of the experimental phenomena and laws of light; but he ven¬
tured to add, as an appendix, a set of Queries, in which form he
could state his matured ideas on the nature and mechanism of light
and yet not incorporate them as an integral part of a scientific trea¬
tise. I shall, by an analysis of these Queries, attempt to give an un-
technical view of his conception of light, and to clear up some of
the mistakes which his followers attached to it. Such an analysis is
facilitated by the fastidious care he exercised, as always, in the choice
of words and clarity of diction. We may disagree with his ideas, and
he certainly is not always consistent in his opinions, but we are rarely
at a loss to comprehend what he has attempted to express.

Newton rather roughly grouped his Queries into three general
divisions; the first section treats of the nature of light, its emission
from luminous bodies, and its relation to matter; this is followed by
an enquiry into the absorption of light by material bodies and its
interpretation as vision; the conclusion, which forms the longest and
most important portion, is concerned with the method of the trans¬
mission of energy through space, and with the general properties of
an sethereal transmitting medium.

I have frequently read and meditated upon these Queries, and each
time I am more profoundly impressed with Newton’s consummate
genius, his pure intellectual integrity, and his reverent humility in

112

ISAAC NEWTON

the presence of the infinite complexity of nature. In them, he is at
his best, far removed from the petty jealousies and intrigues which
marred so frequently his personal relations. They are the choicest
fruit of almost a half-century of meditation. I know of no other
such scientific document so perspicuous, so restrained, and so con¬
scious of the inherent limitation of our thought to penetrate the
essence of things. I have wondered why he should have appended
to a rigorous treatise on light such questionings on so many diverse
topics; perhaps it was the same feeling which animated his Platonic
friends to regard Light as a mystical personification of God.

He had early insisted that a mechanical model could readily be
devised for any limited set of phenomena; in fact, he said that many
models could be imagined for the same set of phenomena. But,
when we attempt to insert several groups of related phenomena into
a larger frame, then these models invariably fail to fit together. At
best, therefore, all such models or hypotheses are but pictures and
aids to memory, or concrete modes of verbal communication. Their
fault and grave danger lie in the tendency they have to make us
confuse what is real with what is fictitious, a confusion peculiarly
obnoxious to him. Worst of all, the history of thought and his own
experience clearly prove that hypotheses always become static and
dogmatic so that new experimental data are judged, and accepted or
condemned, according as they confirm, or contradict, such precon¬
ceived and cherished children of the mind; whereas if they are in¬
dulged in at all, they should remain so fluid and tentative as to be
abandoned or modified so soon as new data are discovered. Admit¬
ting this limited use of mechanical hypotheses, he would still deem
them to be merely fictitious pictures of the material world and ab¬
solutely irrelevant to problems involving life.

Newton H0 postulated that the essence of Light is a Corporeal Sub¬
stance in so far, at least, as to have the mechanical properties of ex¬
tension and motion. Every body is a combination of a material and
of a luminous substance, both of which are granular in structure; the
corpuscles of the latter are very much smaller in size than atoms of
matter; they occupy the interstitial spaces between the material
atoms of bodies and fill vacuous space as a luminiferous medium or
aether. As material atoms by their motions, create the sensations of
tangibility, sound, etc.; so light corpuscles, by their motion, produce
the sensations of sight and temperature and, perhaps, of weight. In

30 Digest of thirty-one Queries appended to the Optics, 4th edition, 1730, pp. 313-382.

ARGUMENT ON THE NATURE OF LIGHT

113

other words, it was inconceivable to him that there could be motion
without something substantial which could move. In this respect he
was dualistic, since he held that energy was the combination of two
irreducible factors, substance and motion.

Atoms and corpuscles, by the impacts of their motion, act mutu¬
ally upon one another; that is to say, bodies upon light, causing its
emission, reflection, refraction, and inflection; and light on bodies
by putting their parts into a vibrating motion wherein heat consists.
This identification of heat with motion he adopted from Descartes.
If this vibratory motion be communicated to our own bodies, we
recognise it as temperature; if it be sufficiently rapid it also affects
the optic nerve, and we perceive the object as luminous. Corpuscles
and atoms act on one another not only by impact but they also
mutually attract each other with a force varying inversely as some
power of the distance between them,—the cause, perhaps, of the at¬
tractions of gravitation, electricity, magnetism and other phenomena.
This supposition of the mutual attraction of matter and light has been
revived by Professor Einstein as one of the fundamental postulates
of his theory of the gravitational field. While it has not been con¬
clusively verified, observations on the positions of stars very near the
sun made during eclipse are believed by many astronomers to con¬
firm it.

The proposal to fill both free space and the pores of bodies with
light corpuscles, everywhere individually of the same order of size
and differing only in density of spatial distribution, involved Newton
in an insuperable dilemma. Either the corpuscles, emitted at enor¬
mous speed from luminous bodies, must be able to travel the im¬
mense distances of interstellar space in straight paths without en¬
countering other corpuscles, although they are assumed to be the
densest in vacuo: or, the corpuscles must persist in the bodies in
which they are enmeshed and merely transmit a vibratory, or wave,
motion to an aether which, itself a substance, would thus involve the
existence of a third elemental substance,—an hypothesis untenable in
his opinion because of its incompatibility with the rectilinear prop¬
agation of light by waves. As Newton’s corpuscular hypothesis
breaks down in explaining the transmission of light, so all vibrational
hypotheses equally fail to provide a comprehensible material source
of light (the moving thing) and a mechanism for transferring en¬
ergy from the luminous object to the aether. As he illogically ad¬
vanced the one supposition or the other, as the exigencies of the

ISAAC NEWTON

114

problem required, so we now, after long vacillation, are vainly trying
to combine a corpuscular theory, under the pseudonym of quanta of
energy, to explain the cause of light, and a wave theory to account
for any phenomenon which involves interference. The mechanism
for the absorption of light, in Newton’s scheme, agrees closely with
that of emission. Corpuscles, after their expulsion from a luminous
source and excursion through space, agitate the atoms of bodies,
which they strike, and give to them their energy.

In order to account for vision, he asks the questions, “do not the
rays of light in falling upon the bottom of the eye excite vibrations
in the Tunica Retina? Which vibrations, being propagated along
the solid fibres of the optic nerves into the brain, cause the sense of
seeing. . . . Do not several sorts of rays make vibrations of several
bignesses [wave-lengths], which according to their bignesses excite
sensations of several colours, much after the manner that the vibra¬
tions of the air, according to their several bignesses excite sensations
of several sounds ? And particularly do not the most refrangible rays
excite the shortest vibrations for making a sensation of deep violet,
the least refrangible the largest for making a sensation of deep red,
and the several intermediate sorts of rays, vibrations of several inter¬
mediate sorts to make sensations of the several intermediate colours ?
May not the harmony and discord of colours arise from the propor¬
tions of the vibrations propagated through the fibres of the optic
nerves into the brain, as the harmony and discord of sounds arise
from the proportions of the vibrations of the air?”

Newton was deeply interested in the problem of vision and wrote
several long and elaborate letters on the subject which the curious
may find given at length in Brewster. As his facts were meagre and
faulty and his conclusions of no present value, it is sufficient to state
that he thought binocular vision was due to the crossing and uniting
of the nerve fibres from the two eyes, in such a fashion that the fibres
meet in the brain to make but one entire picture, half of which in
the right side of the Sensorium [the organ of appreciation, of life
and of the soul] comes from the right side of both eyes, and the other
half similarly from the left side. But he had been much more in¬
fluenced by the later work of Huygens, who had improved and ex¬
tended the wave theory, than has been supposed; we should not then
be surprised when, in a later Query, he questions whether, in spite
of certain advantages of the corpuscular hypothesis, vision is not
caused chiefly by the vibrations of an aether.

ARGUMENT ON THE NATURE OF LIGHT

ii5

A mechanical model must simulate consistently and satisfactorily
the three principal actions of bodies on light,—reflection, refraction,
and diffraction. The mechanism proposed by Newton depends upon
the modification of a stream of light corpuscles by two subordinate
actions. The first of these is a mutual attraction between atoms and
corpuscles which increases as the distance decreases. And the second
is caused by vibrations produced in the aether when corpuscles im¬
pinge on a body; the velocity of the aethereal wave being assumed to
be greater than that of a corpuscle, it alternately accelerates or retards
the speed of light, according as the to-and-fro motion of the vibration
aids or opposes the direction of propagation of the corpuscle.

The first action being granted, he puts the questions: Do not
bodies act upon light at a distance, and by their action bend the rays;
are not the rays of light, in passing by the edges and sides of bodies,
bent several times backwards and forwards, with a motion like that
of an eel; and do not the three fringes of coloured light, seen in the
phenomena of diffraction, arise from three such bendings? We
should accept this explanation if, as he suggests, rays which differ in
refrangibility differ also in flexibility. In that case, their different
degrees of flexibility would separate the colours, when white light
grazed the edge of a body, in the same manner as a prism does by
selective refrangibility. It would also follow that the angles of re¬
flection and refraction are not abrupt but slightly curved at their
apex. Rays of light, because of this bending, are reflected, refracted,
and inflected by one and the same principle, acting variously in vari¬
ous circumstances.

Newton was driven to propose this ancillary wave hypothesis, in
spite of his reluctance, in order to provide a mechanism which
would, at times, increase the velocity of light sufhciently to make a
ray penetrate a transparent body and, at other times, retard it enough
to make it rebound from an opaque surface or even prevent it from
reaching the body. It will be best to give this famous doctrine of
“Fits” in the author’s own words: “When a ray of light falls upon
the surface of any pellucid body, and is then refracted or reflected,
may not waves of vibrations, or tremors, be thereby excited in the
refracting or reflecting medium at the point of incidence, and con¬
tinue to arise there, and to be propagated from thence ? And are not
these vibrations propagated from the point of incidence to great
distances ? And do they not overtake the rays of light, and by over¬
taking them successively, do they not put them into the Fits of easy

ii 6

ISAAC NEWTON

Reflection and Easy Transmission described above? For if the rays
endeavour to recede from the densest part of the vibration, they may
be alternately accelerated and retarded by the vibrations overtaking
them.” 31

Newton devotes the third book of his Optics to the phenomena of
colours produced by successive reflections and refractions in thin
transparent plates. While it may have been the custom of the day to
refer only casually to the work of others, Newton unfortunately
gives the impression that the whole subject, excepting its bare dis¬
covery, was the result of his own labour. Hooke’s name is not even
mentioned, and no one would suppose that he had described all the
essential phenomena of these colours in his Micrographia almost a
half century earlier, or that he had been the source from which
Newton had derived his composite-wave hypothesis. Since these
colours are the result of successive reflections and refractions, New¬
ton added the property of fits of easy reflection and of easy transmis¬
sion occurring at equal intervals to his corpuscular hypothesis as a
substitute to his rival s device of the interference of cethereal waves.
It is, however, a satisfaction, to me at least, that he concludes these
futile speculations with the caution: “But whether this hypothesis be
true or false I do not here consider. I content myself with the bare
discovery, that the rays of light are by some cause or other alter¬
nately disposed to be reflected or refracted for many vicissitudes.”

Such is Newton’s ingenious and famous hypothesis of light. We
ought not to object to it on the obvious ground that it is based on an
absolutely false assumption of fact or that its mechanism is often
unintelligible, so long as men of science are still guided by the belief
that hypotheses are valuable, whether their assumptions are true or
false and whether their mechanisms are intelligible or not. For scien¬
tists to hold that knowledge can be furthered by a false assumption,

31 There has been assumed, in the minds of many physicists, a rather contemptuous
attitude towards Newton s invention of “Fits.” It is worth while to quote the opinion of so
eminent an authority on optics as Biot. In his Life of Newton, page n, he says: “We have
here an admirable example of the universal application of scientific definitions when
framed in strict accordance with experiment. For, though the term fits, inasmuch as it
seems to imply a physical property, is applicable in its first intention to material particles
only, and thus involves the assumption of the materiality of light (a fact of which we
may reasonably doubt, though Newton has never treated it as doubtful), yet the character¬
istics of these fits are described in such exact conformity with experiment, that they would
exist without any change, even were it discovered that light is constituted in any other
manner—that it consists, for instance, in the propagation of undulations: such is the point
of view in which Newton regards these fits in his Optics, 1704, limiting himself to deduce
from them his profound inductions, on the intimate constitution of bodies, and on the
cause which renders them apt to reflect or transmit a particular colour.”

ARGUMENT ON THE NATURE OF LIGHT

117

if only the intention be good, is a curious commentary on their pre¬
tension that science is based on objective facts. At a time when Rdmer
had just discovered the finite velocity of light, it could not be
dreamed that we would some two centuries later be able to measure
so swift a speed in the short stretches of our laboratories. Descartes,
with no experimental data on the velocity of light at his disposal,
had stated that the transmission of light was instantaneous, and yet
when he attempted to explain the phenomenon of refraction he
quietly assumed that its velocity is greater in transparent bodies than
in vacuo where he had assumed it to be infinite. In a moment of
relaxed conscience, Newton forsook his fixed principle that science
must be based on observed facts and measurements only, and in¬
corporated this fiction into his hypothesis. Now, if hypotheses are
valuable aids to the investigation of scientific laws, we should have
to admit that this one advanced truth for two centuries during which
it was supposed that light travels faster in material media than in
vacuo; after that its acceptance would have promoted error because
light had been experimentally observed to have just the opposite
property. If any moral obligation can be attached to scientific en¬
quiry, such a principle of thought comes perilously close to the fa¬
mous doctrine that the end justifies the means. But we can, never¬
theless, claim for Newton’s hypothesis that, in spite of false premises
and obscure reasoning, it is as satisfactory an explanation as later
ones,—for we are still in total darkness as to why, and how, light
penetrates some bodies and is reflected from others.

We are sure of but four facts when a luminous source and its
receiver are separated by vacuous space,—the mechanical energy of
light and heat is not absorbed; it is transmitted rectilinearly and with
a finite velocity; its colour and temperature are not affected. Romer
had discovered this time-interval to be seven or eight minutes for a
distance equal to the earth’s orbit. This distance, of about 92,000,000
miles, divided by the time is called the mechanical velocity of light.
The problem, before Newton, was to invent a mechanical substance
capable of transmitting such a velocity. Experience teaches us of
only two ways of transmitting such an action by mechanical means,
either by a stream of projectiles like bullets fired from a gun or a
periodic motion transmitted as a wave along some elastic material.
The Greeks pictured light by the first method. Descartes had pro¬
posed a pressure method; space was like a rigid rod, if you tapped one
end of it, a ball (his light globulus) resting against the other end

ISAAC NEWTON

would fly off as a result of the transmitted shock. Huygens and
Hooke had changed this idea of instantaneous pressure into a vibra¬
tory action impressed on a fluid medium, whose motion was similar
to the waves impressed on air or water by a tuning fork or an organ
pipe.

Newton returned to the projectile hypothesis because he found a
compressional wave incapable of explaining the rectilinear propaga¬
tion of light and certain phenomena of double refraction in crystals.
He then added a vibratory aether as a contributing cause of other
known phenomena.

He pictured to himself the aether as an excessively rare gas, atomic
in structure and capable of vibrating by alternate condensation and
rarefaction. With his customary thoroughness he made many ex¬
periments on the velocity of sound by timing the echo in Neville’s
Court of Trinity College. He found it to be about 1140 feet per
second and derived a formula expressing the velocity in a gas to be
equal to the square root o f the ratio of the elasticity to the density of

the medium (v—\^e/d). From Romer’s observation, the velocity of
light is very roughly 700,000 times that of sound. As the simplest
composition for an aether, he assumed it to be a fluid, 700,000 times
more rigid than air and, at the same time, with a density of only
1/700,ooo that of air. We must also bear in mind that it must be
so rare as not to retard, by its friction, the motion of the planets to
an appreciable amount, and, at the same time, immensely more rigid
than steel.

At times, Newton identifies the light corpuscles with the aethereal
atoms, and at other times he writes as if the corpuscles were of a
smaller order of magnitude and shot through the pores of the aether
without collision or deviation. However that may be, light while
traversing the aether creates no waves; it is only when corpuscles
impinge on matter that waves occur, as when a stone strikes water,
and then they progress through the aether much faster than light in
order to produce “fits.”

If one is engaged in creating a mechanism to explain light, there
is no apparent reason why the aether should not be forced to serve
as the cause of other phenomena; so Newton, having taken the first
step, lets his fancy have full sweep in order, as I think, to show that
his condemnation of hypothesis was not due to a paucity of imag¬
ination, but to a settled conviction of method. No one can believe
that he expected to be taken seriously.

ARGUMENT ON THE NATURE OF LIGHT

119

In brief, this universal medium of action must have a composition
so complex as to be capable of answering his queries: Is not this
medium much rarer within the dense bodies of the sun, stars, planets,
and comets, than in the empty celestial spaces between them? And
in passing from them to great distances, doth it not grow denser and
denser perpetually, and thereby cause the gravity of those great
bodies towards one another; every body endeavouring to go from
the denser parts of the medium towards the rarer ? . . . Doth it not
cause the attraction of electrical and magnetic actions? ... Is not
vision performed chiefly by the vibrations of this medium, and also,
in general, is not animal motion performed by its vibrations, excited
in the brain by the power of the will and propagated through the
capillaments of the nerves into the muscles for contracting and
dilating them? . . . Nay, even [why not go the limit,] are not gross
bodies and light convertible into one another, the changing of bodies
into light, and light into bodies, is very conformable to the course
of nature, which seems delighted with transmutation?

Newton could not have deceived himself to the extent of not
knowing that such an aether would be merely that kind of an occult
substance endowed with an occult power of doing all those things
which we wish it to do. Like Proteus, in Greek mythology, it
changes its form according to the necessities of the case; it is merely
a fiction, an explanation which does not explain. And so he would
have us regard it: “To tell us that every species of things is endowed
with an occult specific quality by which it acts and produces mani¬
fest effects, is to tell us nothing: but to derive two or three general
principles of motion from phenomena, and afterwards to tell us
how the properties and actions of all corporeal things follow from
those manifest principles, would be a very great step in philosophy,
though the causes of those principles were not discovered: And
therefore I scruple not to propose the principles of motion above
mentioned, they being of very general extent, and leave their causes
to be found out.”

This long discussion of the controversy, which arose in the seven¬
teenth century and which is immensely important in its formulation
of the scientific method, can be best closed by tracing briefly its sub¬
sequent history. A great injustice has been done to Newton. He did
not propose a purely corpuscular theory of light and is not respon¬
sible for the fact that his followers fastened his name to it. He found,
as he thought, insuperable objections to the wave hypothesis of Huy-

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gens and Hooke which were well founded and tried to avoid those
difficulties by a combination of corpuscles and vibrations. The prob¬
lem before the scientists of the eighteenth century was to choose
between occult light corpuscles and an occult aether, which like a
gas vibrated longitudinally; they chose the former as the less repug¬
nant to experience. At the opening of the nineteenth century, Young
and Fresnel, almost simultaneously, gave a new impetus to the wave
theory by the hypothesis of assuming that light vibrations were trans¬
verse to the direction of propagation, although it was necessary to
give to the aether the impossible attributes of being, at the same time,
the rarest of gases and the most rigid of solids. For a time it was
claimed that every problem of light had a satisfactory explanation,
and the development of the elastic-solid theory of light was regarded
as the greatest achievement of the age. It was, unfortunately, an
edifice dazzling in appearance but built on sand. With each new
phenomenon incorporated in its walls, the aethereal substance of its
foundation became more occult. The literature of the subject, for
the first half of the nineteenth century, is a monument to the effort
and ingenuity of physicists to patch up this material aether.

The quietus was given to every type of a material medium for light
when Maxwell published his prediction that an electro-magnetic
oscillation would be propagated through space with the velocity of
light. His significant conclusion was: “If my calculations are cor¬
rect [and they were shortly confirmed by experiment], there are
now two forms of energy, light and electricity, propagated through
space with the same velocity. Since the only function of an aether
is to provide a vehicle which will propagate energy at a specific veloc¬
ity, it would be foolish to fill space with two aethers when one is
sufficient.” The aether, as a kind of elastic-solid has served its purpose,
let us therefore assume light to be an electro-magnetic vibration of
particular wave-lengths and the aether, a something capable of being
electrified and magnetised but with no material attributes of density
or elasticity. It was this hypothesis of Maxwell which called forth
the witticism of Lord Kelvin, that the aether had become merely a
personification of the verb, to wave.

The accumulation of experimental data, especially in the fields of
iadio-activity and of the discharge of electricity in gases, has rapidly
forced even this pseudo-substantial aether further and further into
the pale limbo of discarded ideas. There was little protest made
when Lorentz, and later Einstein, quietly buried it with the remark

ARGUMENT ON THE NATURE OF LIGHT

121

that the aether with its complex of Faraday lines of force was merely
a mathematical formula. With the passing of a substantial aether,
matter as an objective reality has gone also. The world is portrayed as
merely a manifestation of disembodied energy, active and passive at
the same time, and we are drifting rapidly towards the dogma of
the relativists, that truth is to be found only in the mathematical
formula. In a certain way, this idea is true; but it is only a half-truth
and no philosophy, and especially no science, can persist which does
not take cognisance of the equally true objective world of brute fact.

If we contemplate the history of the science of optics during the
two centuries since the death of Newton, we find, on the one hand,
a steady and permanent advance in our knowledge of the phenom¬
ena and laws of light and of its interactions with matter, electricity,
and heat, but, on the other hand, the chronicle of our hypotheses has
been a record of vacillation and defeat. The best efforts for two
centuries have not advanced our real knowledge of the nature of
light one step; in essence, light is still nothing to us but light. If
Newton, at the beginning of modern science, despaired of teaching
his contemporaries the unavoidable limitations of the scientific
method, he would have renounced science today altogether as the
most litigious and dogmatic of task masters.

CHAPTER V

TRINITY COLLEGE. CHARACTER OF NEWTON. CORRE¬
SPONDENCE WITH COLLINS AND OLDENBURG ON
LIGHT AND MATHEMATICS

1669-1674

T he physical aspect of Trinity College in 1669, when the
young Newton succeeded Barrow as Lucasian Professor of
Mathematics, differed greatly from its present appearance.
The Great Court, the most impressive of all college quadrangles,
had been completed at the beginning of the century, except for some
minor changes. Loggan s general view of the College shows a gar¬
den laid out between it and Trinity Street, with a high wall around
the garden on the right hand of the Great Gate as one enters, and
buildings, as at present, between the College and the street on the
left side. Only the two wings of Neville’s Court, extending west¬
ward,^ had been partially completed, and, where Sir Christopher
Wren s Library now stands, there was a wall penetrated by a gate
admitting to the Backs. These buildings provided all the accom¬
modations for the College except the small court forming the
Bishop’s Hostel, which had just been completed. As the College was
practically a self-supporting community it had also a range of low

buildings for stables, brew-house, bakery, and other domestic pur¬
poses.

Although the College had given to the Royalist cause much of its
plate and money, its finances were now on the mend and its students
growing in number. The result was serious overcrowding, some¬
times as many as three or four students shared a single room, and
some of the Junior Fellows had roommates instead of each having
as now a suite of rooms; certainly this is true of Newton in his early
days. During most of his tenancy, building was going on in Neville’s
Court; the two wings were extended in length, and Wren’s impos¬
ing library was erected to join them across the open end. Funds,
however, seem to have come in slowly, and the whole Court was
not completed until 1690. Besides obtaining outside donations, the

122

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123

College drew heavily on its own resources, and its Fellows contrib¬
uted from their personal funds; amongst the latter items, we have
the record that Newton, at one time gave ^50, and at another
loaned Tioo.

The number of members on the Foundation was then about the
same as now, and consisted approximately of sixty Fellows, sixty
Scholars, and sixteen Sizars. But the number of undergraduate stu¬
dents was much smaller, as only forty were admitted in Newton’s
first year, instead of the two hundred, or more, who now enter an¬
nually.

The College was governed by the statutes instituted in Queen
Elizabeth’s reign, and under them the Master, who was appointed
by the Crown, had almost unlimited authority. Associated with him
in the government were the eight Senior Fellows ranked according
to length of appointment. The progress of the Fellows in rank was
slow, so slow that, when Newton resigned his fellowship in 1701,
he had risen only to be tenth on the list after an occupancy of
thirty-three years, and he would not have attained his seniority until
a year and a half later. This unfortunate delay in promotion to
seniority, and an active part in administering the College, was due
to an abuse of the purpose of the fellowships. They were intended,
primarily, to be an aid to young scholars while they were preparing
themselves for the church. Able men, after graduation, were sup¬
posed to be elected to the Foundation for a period of seven years,
thus assuring them an income sufficient to secure them leisure and
opportunity to study, till they could proceed to their divinity de¬
grees, and obtain a parish under the patronage of the College. Only
a relatively few of the Fellows who were appointed to a university
professorship or other office, or to a college tutorship, were expected
to remain with the College permanently. Unfortunately, an increas¬
ing number showed a reluctance to proceed to their divinity degrees
or to exchange the comforts of college life, and the enjoyment of
an intellectual community, for the wretched accommodations of the
average rural parsonage and the dull society of the squire’s house,
where often the parson ranked scarcely above the butler. They per¬
sisted in maintaining their quarters in the College; with but few
required duties, they lapsed too frequently into an idle life, daw¬
dling over trifles and blocking those who were eager and able to
manage the community vigorously.

There are many stories current in Oxford and Cambridge about

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ISAAC NEWTON

the extraordinary vagaries of some of these half-mad recluses who
had developed eccentricities during a long life of dull laziness, un¬
restrained by contact with life and work. One may laugh at these
anecdotes, but the humour is tinged with regret at the spectacle of
the degradation of such a distinguished body of men. One of them,
although it does not refer to Newton’s time, is too good not to
repeat. A Fellow, well over eighty years of age, had become a pure
eccentric; after years of academic idleness, he had absolutely se¬
cluded himself in his chambers and was hardly seen by any one, day
or night. At dusk he would creep down his stairs and, armed with
a stout stick to support his tottering steps, make the round of the
Quadrangle for exercise. Each time that he discovered a worm
during his walk, he would stop, peer at it anxiously with purblind
eyes, and then jab at the wriggling symbol of mortality with his
stick; meanwhile muttering in quavering accents, “Damn you, you
haven t got me yet.” These comfortable life tenures have long since
been abolished even at King’s College, where they persisted longest
and led to the worst abuses; and today Cambridge Fellows enjoy
their privileged life so long as they are worthy of their office and
contribute to the reputation of the College and University.

In this community of scholars, Newton held a distinguished posi¬
tion though he took little part in the management of the College.
It has already been mentioned that living quarters were first as¬
signed to him in what was known as the “Spirituall chamber” and
which was conjectured by Edleston to be the ground-floor room next
the Chapel in the north-east corner of the Great Court. We do
know, however, that Newton and his friend John Wickins, a Fellow
two years his junior and later pastor of the church at Stoke Edith
near Monmouth, still roomed together in 1673. In that year they
seem to have separated, and it may be guessed that it was Newton
who went into other quarters for a grandson of Wickins states:
“The whole furniture of the chambers devolved upon my ancestor
upon Sir Isaac’s leaving the college, and hath with some other arti¬
cles remained in the family ever since.” In 1678, he had a sizar
living with him as the Junior Bursar’s Books contain an entry that
Mr. Newton’s sizar’s chamber was mended over. The first specific
notice of the location of his rooms is an entry in the same book for
the year ending Michaelmas, 1683: “For mending the wall betwixt
Mr. Newton’s garden and St. John’s.” Edleston offers as the most
probable supposition, that he went into them in the summer of

TRINITY COLLEGE

I2 5

1679. These are the rooms pointed out to the stranger, on the first
floor of the entry to the north of the Great Gate. It is a distin¬
guished entry, for the ground-floor chambers were later occupied by
Macaulay and Thackeray. And I recall with pleasure the feeling,
almost of reverence, which came over me when I once, years ago,
took after dinner coffee with the Fellow who then occupied them.
While the analysis of light may not have been made there, a far
greater thing occurred; in them Newton meditated and wrote his
Principia, and spent the long and silent hours in contemplation on
the mysteries of the universe.

Besides his living rooms, Newton had assigned to him a room
which he fitted as a chemical laboratory and where he spent days
and nights at certain seasons of the year, oblivious to other duties
and occupations. At the head of his staircase, he had mounted one
of his own reflecting telescopes, and from one of his windows a
flight of stairs permitted him to descend to the little garden laid out
between the college and the street. This garden plot seems to have
been reserved for his private use; and one gets the impression that
in its short length, the great and lonely scholar paced up and down
for the little exercise he was willing to abstract from his hours of
study.

An interesting anecdote of these rooms comes down to us from
a grandson of Bentley, who was a freshman in 1747; speaking of the
kindness of Walker, the Vice-Master, who then occupied them, he
wrote: “He frequently invited me to his rooms, which I had so often
visited as a child, and which had the further merit with me as hav¬
ing been the residence of Sir Isaac Newton, every relic of whose
studies and experiments were respectfully preserved to the minutest
particular, and pointed out to me by the good old Vice-Master with
the most circumstantial precision. He had many little anecdotes of
my grandfather [Bentley], which to me at least were interesting,
and an old servant Deborah, whom he made a kind of companion,
and who was much in request for the many entertaining circum¬
stances she could narrate of Sir Isaac Newton, when she waited upon
him as his bedmaker, and also of Dr. Bentley, with whom she lived
for several years after Sir Isaac left college, and at the death of my
grandfather was passed over to Dr. Walker, in whose service she
died.” 1 Thus fate has preserved the name of Deborah, whose associa¬
tion with such great erudition was not capable of teaching her to

1 Edleston, p. xliv..

126

ISAAC NEWTON

write her own name, and whose interesting memories the negligence
of others has failed to transmit to us.

When Newton was appointed Lucasian Professor, at the age of
twenty-seven years, he was mature in mind and character. As our
interest in such a man naturally centres about his intellectual life, it
is important to give a sketch of his appearance, habits, and character
before narrating the events of his life which follow after this definite
recognition of his genius; and especially so, because the traditions
and stories which gathered about him have come down to us very
often undated and confused.

We have no description or likeness of Newton’s personal appear¬
ance in his youth; there is, to be sure, a portrait by Lely said to have
been painted when he was a bachelor of arts, but it is probably not
authentic as it shows little resemblance to his later portraits, and also
Newton was at that time too obscure and too poor a man to have
engaged the brush of so eminent an artist. 2

With the exception of the portrait painted by Kneller, in 1689,
shortly after the publication of the Pnncipia, all the extant pictures
of Newton were done when he was an old man living in London;
and most of them are so evidently idealised to express the artist’s
conception of an heroic thinker that one gets but a vague impression
of the man. In addition, the figure is stiffly posed, and the full-bot¬
tomed wig conceals the shape of the head. The most faithful like¬
nesses are the one painted by Gandy in 1706, and the three by Thorn¬
hill shortly afterwards; in spite of rather striking differences, they
agree in general appearance.

Newton’s most notable features are the power and expanse of the
forehead, and the appearance of concentrated meditation in the brow
and eyes. The profile, as drawn by Thornhill, makes the forehead
high and receding and shows a most extraordinarily long and un¬
broken curve from the chin to the crown of the head. The nose is
long, thin, and prominent, and the line of the bridge is wavy. But,

2 The following list of important portraits is given by Professor D. E. Smith, who has
probably the largest collection of Newtoniana in existence. (C/. Greenstreet, p. 171.)

Portrait by Lely, date 1665-8. Original in possession of Viscount Cremorne, probably
not authentic.

By Kneller, 1689. In possession of Earl of Egremont.

By Gandy, 1706. Formerly in possession of J. A. Walter, Esq.

By Thornhill, 1709. In possession of Trinity College.

By Thornhill, two other portraits. Original of one of them in Hurstbourne Park.

By Vanderbank, 1725. In possession of Royal Society.

By Vanderbank, 1725 [?]. In possession of National Gallery of London.

By Seeman, 1726. In possession of Thomas Hollis, Esq.,

By Roubiliac, statue in antechapel of Trinity College.

TRINITY COLLEGE

127

the lower part of the face is in strong contrast with the strength and
nobility of the upper half. The chin is square and broad, while the
lower jaw appears to be underhung, and the lower lip is pinched
and drawn in; so that the expression is one of excessive cautiousness;
and one infers him to have been of a suspicious and obstinate tem¬
perament. In height, he was not above middle size, and he became
stout in his later years as would naturally result from his sedentary
habits.

Conduitt tells us that Newton “had a lively and piercing eye, a
comely and gracious aspect, with a line head of hair as white as
silver, without any baldness, and when his peruke was off was a
venerable sight.” A lock of his hair, silver white and unusually fine
in texture, is still preserved amongst his relics in Hurstbourne Park.
He was gray headed when he was thirty, which Stukeley quaintly
attributed to a hot and dry constitution. Quite the contrary is a
description by Bishop Atterbury who, in a letter, wrote: “In the
whole of his face and make, there was nothing of that penetrating
sagacity which appears in his compositions; he had something rather
languid in his look and manner, which did not raise any great
expectation in those who did not know him.” And this opinion is
confirmed by Hearne who found “Sir Isaac was a man of no very
promising aspect. He was a short well-set man. He was full of
thought, and spoke very little in company, so that his conversation
was not agreeable. When he rode in his coach one arm would be out
of his coach on one side, and the other on the other.” As Newton
owned a sedan chair, and not a coach, this odd habit which seems to
have made his passage in town noticeable would be easier in that
narrow vehicle.

These different opinions may perhaps be reconciled, as the medi¬
tative, inward look of the scholar may, to the casual observer, give
the impression of an abstracted and dull appearance; but, when
aroused, he may have had the intent, piercing eye which Conduitt
remembered. His eyes were full and protuberant, and he several
times mentions that he was near-sighted, too near-sighted to make
astronomical observations; Flamsteed insinuates that he would guess
at words rather than confess his inability to read small print, or wear
spectacles. Newton believed that his eyes were normal when he was
a child because he remembered being able to see Grantham church
spire like a stick six miles away. His eyes, however, were strong
and were never tired by reading, so that to the end of his life he

128

ISAAC NEWTON

could read the smallest print by the light of a coal fire without spec¬
tacles.

During his Cambridge days he was inattentive, even to sloven¬
liness, in his dress and habits. There are many references to this care¬
lessness, such as “Newton hath come into the Hall without his band,
and went towards St. Mary’s in his surplice”; this indifference to
dress grew into a legend, as indicative of the great scholar, for there
is a Staffordshire figure of him, in my possession, in which the neck¬
band is loose, the stockings ungartered, and the breeches unbuttoned
at the knee. But, when he moved to London, he adopted a more
seemly costume and, on occasions, considerable elegance. With the
later authority and full recognition of his genius, his whole aspect
grew in power and dignity, and his latest portraits indicate a man
fully conscious of his achievements and position.

In spite of his untoward birth and delicate infancy, the life on the
farm must have established Newton’s health at a fairly early age and
have given to him a rather extraordinary constitution. Even as a
boy, he shunned rough sports and, from manhood on, we have no
intimation that he diverted his mind with amusements or felt the
need of any bodily exercise except the slow pacing of his little college
garden enclosure. Yet he had only two serious attacks of illness;
once as an undergraduate, he had a temporary break-down from too
persistent observations of a comet for many nights, and when, after
the exorbitant labour he had put into the composition of the Prin¬
ciple he suffered from insomnia and such excessive nervousness that
reports were spread of his being mentally deranged. As often hap¬
pens with solitary men, he took much interest in his health, and both
doctored himself during his minor ailments, and suggested simple
remedies to his friends. A significant indication of his prevailing
good health is that even in those days of reckless tooth-pulling he
lost but one from his entire set. A constitution, which could stand
irregular hours, irregular meals, a sedentary life, and yet each morn¬
ing experience no dullness of the mind, is as baffling as are some of
the traits of his character. It is noteworthy that four of the most
distinguished natural philosophers of the time, Newton, Whiston,
Flamsteed, and Hooke, attained fame in spite of an unpromising
birth and, with the exception of Newton, persistent ill-health.

He was abstemious and regular in his diet, except when he was
so immersed in the fascination of creative work as to be forgetful
whether he had eaten or not. As a young man, he enjoyed wine and

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129

beer and, if we can credit a legend, he occasionally smoked. As he
grew older, he limited himself to a little wine at meals, and gave up
tobacco because he would not be dominated by habits. He, also, said
of himself that he learned to go to bed early, but then he considered
midnight, or later, as early and, during strenuous times, he fre¬
quently worked all night, finding that a short nap entirely refreshed
his mind. He was not interested in travelling and lived almost con¬
stantly in the College as is shown by the record of the Exits and
Redits of Bachelor Fellows and Scholars. During the long vaca¬
tions, and occasionally during term time, he returned to Wools-
thorpe; his attachment to the scenes of his youth and to his family,
especially his mother, seems to have been by far the strongest im¬
pulse in his social life. Very rarely, he went to London or visited
acquaintances elsewhere; there is no indication of the least curiosity
to inspect the historic or artistic monuments of England, to enjoy its
scenery, or of any desire to relieve the monotony of a fixed abode.

In his social life, Newton living at a time when class distinctions
were very rigid, was in the anomalous position of one whose family,
by occupation and income, were ranked practically as yeoman farm¬
ers but at the same time had the rights theoretically belonging to the
gentry. To be a lord of a manor and, at the same time, a sizar at
college would make a proud youth avoid the companionship of
humble students and uncomfortable in the society of gentlemen.
His first opportunity to associate with men of gentle birth came
from his intimacy with Charles Montague, afterwards Earl of Hali¬
fax. And from that time it is easy to note a change in his disposi¬
tion. He grew restive in the academic life and sought a political
position which would bring social recognition. He cultivated ac¬
quaintanceship with such distinguished men as Boyle, Bentley,
Locke, Pepys, Henry More, and stood for Parliament as frequently
as an opportunity presented. He wearied of Cambridge society and,
with almost abject submissiveness, petitioned his friends to secure
him an office in London. And when he finally succeeded, he left
Cambridge, his colleagues, and his work, without an expression of
regret; he cultivated the society of the nobility, was a welcomed
guest at Court, and derived the greatest satisfaction from the respect¬
ful attentions of eminent foreigners whom he entertained frequently
and handsomely. This attitude, which links together Newton and
Shakespeare,—that the reward of genius in any line is to be found
in social and political distinction,—is peculiarly British and has been

130

ISAAC NEWTON

one of their sureties of high principles in government. At bottom,

it comes from the same conviction which animated Rome in her

greatest days, that the first and highest concern of the citizen is the
State.

Newton never lost his interest in Woolsthorpe; he returned there
whenever his duties at Cambridge permitted, and most of his great¬
est discoveries came to his mind as he meditated in the quiet seclu¬
sion of his farm. He helped to restore the church at Colsterworth
and intended to establish and endow a school there. After his moth-
er s death, he kept a close watch over his tenants and his rights as
lord of the manor, and desired to trace his genealogy to the county
ami y o a Sir John Newton. His love for his mother was the
strongest tie in his life and he felt it to be so intimate that he left no
word, or letter, about their tender relationship. With the exception
o his niece, Catherine Barton, the rest of his immediate family were
more of a concern and worry to him than a pleasure. She, alone
was in any way comparable to him; she has come down to us as the
beautiful, witty, and virtuous Mistress Catherine Barton; she pre-
si e d over his house and entertained the best society of London; and
s e ’ n fj, y y the marriage of her daughter, became the ancestress
o the Earls of Portsmouth. As Newton advanced in fortune, he
continued to aid his stepsisters and their children, setting ’ the

nephews up in business and making large gifts to his sisters and
nieces when they married.

With the exception, perhaps, of Montague, Newton had no in¬
timate and personal friends who penetrated the ivory tower in which
he jealously guarded his inner life. How aloof he wished to be is
epitomised in his almost agonised cry that he would publish nothing
more as it would result only in attracting acquaintance, what he
most sought to avoid. Towards Boyle and Wren he showed a deep
respect, and next to Montague his most congenial friends were
Henry More and John Locke; but even they regarded him as diffi¬
cult and nice” to approach. Men of science, such as Hooke, Flam¬
steed and Leibniz, who ventured in the same field of work and who
felt themselves competent to criticise him, were met by chilling
rebuffs. The altercations with them were due to the interference
with his time which their criticism caused; and to his almost morbid
sensitiveness to any opposition, which to him was synonymous with
a reflection on his personal integrity and honour, rather than to a
scholarly difference of opinion. If an explanation of his ideas was

TRINITY COLLEGE

I 3 I

not sufficient to meet with acquiescence, he abruptly stopped his
correspondence; and if he was further opposed, he became an im¬
placable and, even at times, an unscrupulous antagonist.

Newton’s relations with his Cambridge colleagues can be de¬
scribed as formal. He must have been intimate with his chamber-
fellow, Wickins, and he entertained at times; but we get the impres¬
sion that he rarely mixed in the academic social life. If one were to
present him at his best, it would be in his intercourse with young
men. He had the power of arousing in them devoted admiration
and loyalty; and he, in return, showed towards them a certain grave
courtesy which was altogether admirable. From the nature of their
relationship, he would not fear intrusion on his time or criticism of
his ideas; he gave them wise and kindly advice, and was indefatiga¬
ble in promoting their success. Collins, Gregory, Halley, Cotes,
Fatio, Keill, Demoivre, Montague, and others, were his ardent par¬
tisans, and they resented any criticism of him or of his work. This
power of attracting young and brilliant scholars is the best and most
genuine tribute which can be given to his character. To them he
showed that integrity of mind, purity of thought, and generosity of
spirit, which made Bishop Burnet designate him as the whitest of
souls. Because of the publicity in which he lived, his altercations
have been engraved on our minds; and we forget that they were but
incidents in a long life, which on the whole was one of uniform
kindliness and of high principles.

If we except Newton’s affection for his mother and for his niece,
Catherine, women had no influence in his life; esteem he may have
had for a few, but passion had been omitted from his nature. He
visited occasionally at country houses but scarcely a reference to any
woman is to be found in his correspondence or in his affairs. To
break off his boyish engagement with Miss Storey left his serenity
unruffled, and their friendship unembarrassed. On the strength of
a letter, dubious in meaning, some have supposed that he proposed
marriage, late in life, to a Mrs. Norris, but the affair seems incred¬
ible. There is another legend which has all the ear-marks of the
invention and wit of the undergraduate mind with its stock convic¬
tion of the absent-mindedness and absorption of the scholar. An
apocryphal scene has come down to us, afterwards illustrated by the
ingenious Cruickshank. Some of his colleagues are said to have in¬
duced Newton to propose to a young lady. During what should
have been an absorbing conversation, while tenderly holding her

132

ISAAC NEWTON

hand, the philosopher s mind wandered into other fields of thought;
instead of raising her hand to his lips, he absent-mindedly used her
little finger as a tamp for his pipe. Aroused by her sudden exclama¬
tion of pain from the heat of the embers in place of the pleasure
which should have come from the warmth of love, Newton ex¬
claimed, Ah, my dear Madam, I beg your pardon! I see it will
not do! I see, I see that I am doomed to remain a bachelor .” 3

With these exceptions, Newton’s inner and real life might have
been passed in a world destitute of women and but rarely populated
with men. It is little wonder that his contemporaries have passed on
to us the impression that he was not a mortal man, but rather an
embodiment of thought, unhampered by human frailties, unmoved
by human ambition. We can offer this remoteness as a possible cause
for the legends which grew up about his Trinity days. His fellows,
feeling his aloofness from human society and unable to understand
how a man could live without intimate companionship, would natu¬
rally invent, or transfer to him, stories of a fondness for animal pets
to comfort his loneliness. So we have the pathetic story of the little
dog Diamond who, on upsetting a candle and burning a mass of
important manuscript, drew on himself only the stilted reproof:
Diamond, Diamond, thou little knowest the damage thou hast
done.” So also we may regard the legend that, bothered by the rest¬
less entrances and exits of a favourite cat, he cut a hole in his room
door for her convenience. When, after the habit of female cats, she
presented him with kittens, he foresaw a new disturbance to his
peace and philosophically cut another, and smaller, hole in the door
for them. Of themselves, they are undoubtedly trivial fictions; he
never had either dogs or cats in his rooms, or any fondness for them;
but they are of value as they express in a striking and homely man¬
ner the unofficial attitude of students and colleagues towards him
during his long years of college life.

Most of the authentic stories of Newton’s absent-mindedness clus¬
ter about his indifference towards food. He seldom went to Hall
for dinner but had his victuals brought to his chamber, and was
often so deeply engaged in study that he neglected to eat them till
supper; if he entertained and went for wine, there was danger of
his forgetting his guests. Even in London this habit persisted, and

f , 3 , p hls f story ™ ust been widely spread during Newton’s life-time. John Bernoulli

told Professor Bjomstahl that: “sagte uns, Newton sey ebenfalls sehr zerstreut gewesen, und
habe einmahl den Finger ernes Frauenzimmers genommen, um seine Tabakspfeife nachzu-
stopfen.” Edleston, note 196, p. Ixxx. P

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his niece must have made special arrangements for him as one sepa¬
rate from the regular domestic regime. The following note given
to her husband indicates that he led a solitary life in his personal
apartments: “He was always called a half hour before dinner, and
would let his dinners stand two hours; his gruel, or milk and eggs,
that was carried to him warm for supper, he would often eat cold
for breakfast.” It would, however, be quite erroneous to think of
him as the perplexed dreamer who commits ludicrous blunders. It
may be true that: “After he printed his Principia, the students at
Cambridge said, as he passed by, there goes the man who has writ
a book that neither he nor any one else understands.” Most men did
not understand it, but he did; and his occasional absent-mindedness
was due to concentration, not to distraction, of mind.

It is easy to summarise Newton’s character as habitually generous,
pure-minded, pious, and self-disciplined:—but how to reconcile other
qualities usually attributed to him; modesty with his assurance of
the superiority of his discoveries; his intellectual integrity with his
mutability of temper and inconstancy of conduct; his stiff insistence
on an exclusive right to his ideas which he kept secret, with his
indifference, even repulsion, towards popular fame; his moral prin¬
ciples with his treatment of friends and rivals. Such contradictions
can be accounted for only as the result of antagonistic traits of char¬
acter. The gods had showered on him, at birth, extraordinary gifts
such as have been given to almost no other man, but some evil fate
cursed him with a suspicious and jealous temperament which marred
his life. This taint in his blood did not show itself in the form of
ordinary vanity, but in an inordinate sensitiveness to any personal
criticism or to a reflection on his personal honour. In spite of his
love of meditation and of peace free from all distractions, it involved
him in constant quarrels and altercations; and during a long and
illustrious life it raised an impenetrable barrier between him and
other men. To his friends, he was never more than lukewarm and
he kept them constantly uneasy lest they had offended him; to his
rivals he was, at times, disingenuous, unjust, and cruel.

In his intellectual character also, Newton presents this same baf¬
fling problem of conflicting tendencies. Since his powers as a natural
philosopher, both as a theorist and as an experimentalist, were so
supreme, it is not strange that his contemporaries, seeing him im¬
mersed in scientific work for thirty years, should have supposed
science to have been congenial to his temperament, and to have been

*34

ISAAC NEWTON

regarded by him as of the greatest importance as an end in itself.
Nor is it surprising that his later biographers have echoed the same
opinion. But how can we make this judgement conform with his
statements that mathematics was a dry and barren subject; that sci¬
ence was such a litigious taskmaster that one might as well be per¬
petually engaged in law-suits; that he grudged the time he had spent
on it to the hindrance of other matters dearer to him? On the other
hand, during those years, apparently devoted to science, he was
deeply interested in history and religion; and during his last thirty
years in public life, he was rarely without a pen in his hand writing
draught after draught of his meditations on those subjects. Is it not
probable that his mental endowment made his entry into science,
as a profession, inevitable, and the discoveries which came to his mind
drove that wonderful machine to work out their solution, as it were,
independently of his will or desire? Because of the rare quality of
his genius, he was able to transcend other men in science and yet
regard it for its own sake as of little more value than an intricate
game of chess. In common with the scientists and divines of the
day, he believed that, natural laws having been ordained by God,
their discovery would be a support to religion by disclosing the
divine will and purpose. Our chief duty and interest were to be
found in the study of the relations of man to God and in the recon¬
ciliation of the new mechanistic philosophy with the doctrines of
Christianity. Whatever had been his early training, he became a
convinced believer in the Protestant tenet of the ultimate responsi¬
bility of the individual towards doctrines of faith. Intellectually
sceptical of the plenary inspiration of the Bible, he yet devoted im¬
mense labour to the task of proving its moral inspiration and author¬
ity, and its prophetic revelation of future events. Heterodox towards
some of the fundamental articles of faith of the Church of England,
he still maintained unquestioningly his connection in that Church.

Of Newton’s minor characteristics, the one to show itself first was
his manual dexterity. It began with the fashioning of toys, and was
continued in the habit of making apparatus and of experimentation;
he also loved penmanship and cultivated a variety of hands which
in his old age developed into a fatal facility for mere writing. So,
also, Newton, as a boy, was fond of drawing, and Stukeley thought
the practice had been continued, as he asked Conduitt to send a
sketch to him as a remembrance of his friend. He is represented to
us as having been totally indifferent to art, but in his boyhood he

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certainly had a taste for pictures, and he once made the unexpected
statement that he could have been a poet, as he excelled in writing
verses. There are many examples of men who found pleasure in the
arts during the emotional period of their youth, which later became
dulled by the occupations and interests of later life. The belief in
his complete indifference to art and literature rests on a few anec¬
dotes. He once said that he had heard but one opera, and was bored
at the end of the second act; again, when the Earl of Pembroke’s
collections were praised, he spoke sarcastically of him as a lover of
stone dolls. Too much weight should not be attached to such casual
statements, taken out of their setting, as Newton could not have
been quite so unhuman a character as tradition has made him; and
some sparkle of humour and sarcasm should be left to him. The
other instance, which has been often cited, occurred during an
acrimonious quarrel which arose as a result of Bishop Hare’s critique
of Bentley’s edition of the Fables of Phcedrus. It was carried on
with such asperity as to cause much scandal, and Newton is said to
have complained that two eminent divines were “fighting with one
another about a play-book.” But, this expression of contempt was
not directed against poetry, but against the impropriety of two
divines thus lowering their sacred calling, a matter towards which
he was very tender. Probably, the safest opinion is, that art and
literature played a very minor part in his life.

In all the ordinary affairs of life, Newton was notably patient and
gentle; traits which showed themselves particularly in his sympathy
towards suffering. He could not bear the sport of hunting, and he
objected to one of his nephews, because he killed birds. Whiston
spread the report that he abstained from eating rabbits because they
were strangled and from black puddings because made of blood.
But his niece denied the report, and said he followed the rule of
St. Paul to take and eat what comes from the shambles without ask¬
ing questions for conscience’s sake.

Before concluding this sketch of Newton’s character a word
should be said about the causes of the quarrels which plagued his
life. They bulk too large in our estimate of his character as, after all,
they occupied but a small part of a long life which was, on the
whole, exemplary; and we must also make allowances for his con¬
stitutional irritability when criticised, a trait which such inordinate
flattery as was given to him could not fail to intensify.

The first cause of his troubles was a result of his own high stand-

136

ISAAC NEWTON

ard of work and of his reluctance to publish. He maintained through
life the high ideal that no work should be made public until the
utmost possible finish had been given it. This desire is not unique
with him but he also thought that no work should be criticised until
the reader had prepared himself for the task with the same exhaus¬
tive meditation. As a consequence, he was puzzled and exasperated
by hasty opposition; and he justly complained that he was mis¬
understood because his critics had failed to grasp his purpose. The
same is true of his habits of composition. He sought with painstak¬
ing care for the right word and for a lucid style.

In contrast with the diffuse treatises on scientific topics, his own
work was cast in the form of geometrical theorems and was ex¬
pressed with excessive brevity; it is not an exaggeration to state that
it required the efforts of the greatest mathematicians for a century
to grasp and elucidate fully his Principia, and few scientists today
have a correct idea of his theory of light, and still fewer, of his
philosophy. This obscurity does not result from laxity of expression;
but from the omission of illustrations and explanatory clauses which
are aids to ordinary men. His style is accurate, clear, and concise,
and he was exacting in his use of words.

Where he felt his exclusive rights of discovery to be involved, no
one could be more determined to assert himself. He held jealously
to the conviction that if he had made a discovery, it was his personal
property for all time, even if he kept it locked in the secret cham¬
bers of his own mind. If another should later make the same dis¬
covery and publish it first, he held to the opinion that no rights
were attached to priority of publication; the author had merely tres¬
passed unwittingly on Newton’s property and should receive no credit.

The second cause of Newton’s troubles came from the state of
science which his inherent reluctance to publish, and his ideas on
priority of rights, greatly accentuated. Before the middle of the
seventeenth century there were no scientific journals in which the
progress of invention could be quickly disseminated and credit be
properly assigned. The only methods of publication were the writ¬
ing of books, or of letters. Neither method was appropriate, the
composition of a book was too slow, and letters were ephemeral,
restricted in circulation, and had their unsavoury side. At the same
time, the advance of science was then extraordinarily rapid, espe¬
cially in pure and applied mathematics. Discoveries came so easily,
and so rapidly, that it would have been difficult, under the best of

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circumstances, always to assign them to their proper source. Ac¬
cusations of plagiarism, and even its prevalence, were common and
widespread. Efforts were frequently made to protect rights by an¬
nouncing, and at the same time concealing, a discovery in the form
of an anagram, or jumble of letters, till the finished work could be
published in a book. Newton’s inherent reluctance to publish kept
his suspicions aroused and aggravated his disputes.

If Newton’s character were such as has been described, one can
imagine his anxiety when he was suddenly called upon to succeed
the veteran and distinguished Barrow. There must be no failure, he
must not only maintain the high standard set by the first Lucasian
Professor but he must bend every effort to surpass his predecessor.
He had chosen optics for his subject and there, also, he came in
direct competition with Barrow who had just published his own
lectures on the same subject. It is not surprising that these first
years are barren of incident. In addition to his professorial work,
he carried on with unremitting energy his experimental work in
light, grinding and polishing of lenses, working on his reflecting
telescope, and investigating the best alloys for his metallic mirrors.
He must have been spurred to even greater effort by the appearance
of Hooke’s Micrographia with its wealth of material on the various
phenomena of refracted light and the composition of colours. Hooke
was a competitor to be feared as so keen a mind might at any
moment snatch from him the fruits of his own incomplete work.

Besides treating in his lectures the subject of geometrical optics in
a concise and elegant manner, Newton added his own new discov¬
eries and described in detail his experiments to prove the specific
refrangibility of colours and the composition of white light. He also
discussed the advantages of the reflecting telescope. The lectures, with
the title of Lectiones Opticae, were written and delivered in Latin.
The style is lucid and condensed; but his exposition would tax the
ability of his auditors since he here, as in his later work, omitted in¬
termediate steps and illustrations. The course comprised thirty-one
lectures delivered consecutively, and without repetition, between Jan¬
uary 1669/70 and the end of 1672. The manuscript, except for the
last two or three pages and marginal notes, is not in the author’s
hand-writing. It was, as required by statute, given to the Vice-Chan¬
cellor and delivered by him to the Librarian, Robert Peachey, to be
preserved in the University Library. Though much of the material

i3»

ISAAC NEWTON

was later incorporated in his Optics, the lectures were not published
till 1729.

The specific duties of the chair were not onerous as the professor
was required to lecture only once a week during term-time on some
portion of geometry, arithmetic, astronomy, geography, optics, statics
or other mathematical discipline. On two days a week during term-
time, and on one day during vacation, if he was in residence, he was
expected to confer with students in his chambers. That Newton
carried out this provision, at least occasionally, is known because
Henry Wharton states in his autobiography that: “He attained
no mean skill in mathematics. Which last was much increased by the
kindness of Mr. Isaac Newton, Fellow of Trinity College, the incom¬
parable Lucas-Professor of Mathematics in the University, who was
pleased to give him further instructions in that noble science, amongst
a select company in his own private chamber.” 4 It is easy to understand
that the novelty of subject and rigorousness of treatment of his lectures
would repel most college students. And we know that he had few
to attend them; often finding no one present, he left the room and
returned to his private work. This small attendance at his lectures
occurred in spite of the official letter of Charles II confirming the
Lucasian statutes, by which all undergraduates after their second year
and all Bachelors of Arts to their third year (“usque ad annum
tertium”) were required to attend them. The Professor could con¬
tinue to hold a fellowship, but he was forbidden to receive pay for

any other university office, except that he might be a Tutor to Fellow-
Commoners. 5

How closely Newton remained at his work in Cambridge, during
these first years, can be seen from the record of Exits and Redits of
Bachelor Fellows and Scholars which were kept in the book of the
Muniment Room. With the exception of a short absence from No-
vember 26 to December 8, 1669, he lived in College continuously be¬
tween September 29, 1668 and April 17, 1671. As his published corre¬
spondence begins with the year 1669 we can glean from his letters
something of his personal life and intellectual pursuits. His first
correspondent was John Collins whose letters have been preserved for

4 Edleston, p. xlv.

prohib i'‘ 0 P wiU a f“ unt f °r °ur not finding Newton’s name at any time among
the College or University Officers.. He availed himself of the privilege of taking Fellow
Commoners as pupils in two instances only: Mr. George Markham, afterward? Baronet
and F. R. S„ entered June 26 , 1680, and Mr. Robert Sacheverell, whose mother was daueh-

September xT” 687" **“ * ** Bar ° nCt ° £ * he name ' emcrtd

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the most part in the very valuable collection of the letters of scientific
men made by the Earl of Macclesfield.

Collins was an important and useful member of the scientific world
of his time. He was a self-educated man, who lamented that he had
been unable to attend a university. But he had, from a love of mathe¬
matics and science, become proficient in those subjects and had
eagerly developed a large correspondence with the notable men of
his time. He tells us that he lived in London and held the position of
secretary and member of the Council of Plantations. He, like other
public servants of the time, suffered from the genial habit of the
Stuarts of restricting the payment of actual money to those who min¬
istered to their personal interests rather than to the public welfare.
In a letter to Dr. Beale, he laments: “I have been employed near 2%
years under Mr. Slingesby, mint master, as secretary (and a member)
of the Council of Plantations, and have received but little more than
the tithe of my pay. A pension I had of £50 per annum, half my
salary, a little while of the King, for the loss of my place as an ac¬
countant in the Excise Office, by reason of altering the administration
thereof since the late Lord Treasurer’s death, and that hath been
stopped these twelve months, as is likewise my wife’s pay as laundress
of the table linen to the Queen; the King’s debts and occasions for the
war diverting the money. Albeit I am exceedingly obliged to Bp.
Ward for speaking to the Lord Clifford for his kindness to me, as I
am to Sir Robert Moray in the like kind. And now the Council of
Plantations is likewise to be a Council of Trade; and Mr. Slingesby,
conceiving the trouble will be great, and the pay as uncertain, leaves
his secretary’s place, and advises me to leave that employment and to
manage the Farthing Office, to deliver out all, that are coined, on
Tuesdays, Thursdays, and Saturdays, in the mornings, in crown-
papers ready tied up; the salary £50 per annum, and a fair dwelling
house which I think may be in or near Fenchurch-street: where,
having a convenient shop, I intend, God willing, to set up a station¬
er’s trade, (and have a promise of serving the Mint,) and afterwards
hope to fall into the printing of books, especially some of the copies
of the members of the Royal Society and some of my own, particu¬
larly one of the modern advancement of mathematical sciences, and an
account of the best authors of that kind, and some others which I
intend, of which more hereafter.” 0 He also tells us that he had a wife

6 The writer’s diction may be slovenly, but it is lively and the reader can, if he wishes,
get an intimate picture of the confusion existing in the government of Charles II. Maccles¬
field, I, p. 201.

140

ISAAC NEWTON

and children, and that his wife was the younger daughter of Mr.
William Austin, who had been one of His Majesty’s cooks when he
was Prince of Wales, but had served as master cook of Wadham
College, Oxford, during the interregnum. After the Restoration he
had returned to the post of master cook to Charles II; and Collins was
then living with his father-in-law in Petty France, Westminster, over
against the Adam and Eve.

It is greatly to his credit that, although of humble origin, Collins
became the familiar friend and counsellor of such a distinguished
circle. At a time when there were no journals giving scientific news
and articles, he became a sort of clearing house, spreading the news
of recent work and answering enquiries. He regularly supplied in¬
formation of new work and purchased books, especially from the
continent, for his friends. Communication was slow and he once
wrote that, “We are here so unhappy that we cannot get books that
are common to be had in Paris, and he mentions “two which were
extant six years before E)r. Wallis heard of either, though he was not
a little concerned in both. He tells us, also, there was so little sale for
books in England that treatises by the most distinguished authors
could not secure a publisher. For that reason he determined to become
a publisher himself, to assure the publication of important works, to
attend to correcting the proofs, and to arrange for their sale.

He at once perceived Newton s genius and was largely responsible
for spreading his reputation outside of Cambridge. With great tact,
he constantly urged Newton to publish his mathematical work, and
in such a way as not to offend his sensitive nature. This tact was
especially noticeable when he acted as intermediary in a correspond¬
ence between Gregory and Newton concerning the reflecting tele¬
scope; it was no easy task to cement a friendship between the inventor
of the instrument and its successful creator. So long as he lived the
relations between Newton and Leibniz also were dignified and amica¬
ble, and we may be sure his influence would have been exerted to coun¬
teract the^ advice of more indiscreet and less scrupulous partisans.

Collins s acquaintance with Newton began with a curious and
typical incident. The Biographia Britannic a 1 gives the story in the
following form. Lord Brouncker had arrived at a method of finding
the area of an hyperbola in terms of an infinite series. With the help
of this hint, and the use of Wallis’s method of division by series,
Mercator published in his ho gar it h m otechnia, in 1668, the actual

7 Art. Newton.

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solution of the problem. As it was the first time that the area under
a curve had ever been calculated by the use of the new analytical
geometry, it attracted much attention and came under the notice of
Barrow. He remembered that Newton had been interested in infinite
series during his retirement at Woolsthorpe because of the plague.
But he did not know what had been the exact nature of the young
student’s work, and he certainly never dreamed that the same problem
had been solved not only theoretically but that, with boyish enthusi¬
asm, the area of the hyperbola had been actually computed, in 1665,
“to two and fifty figures by the same method.” When Mercator’s
work was thus communicated to Newton, he brought to light those
papers of his which had remained for four years entirely unknown
to his teacher, and which included the essential portions of his cele¬
brated tract De Analysi per Aequationes Numero Terminorum In -
finitas. “The doctor perusing it, stood amazed at the prodigious per¬
formance, and immediately acquainted his friend Collins with it; at
whose request he afterwards obtained leave of Mr. Newton to send
him the papers.” Thus it was Collins who was the first to make New¬
ton known to the world, since he made, and dispersed, copies to all
the eminent mathematicians of his acquaintance. And this incident
is supposed to have persuaded Barrow to recommend him as his
successor in the Lucasian professorship.

During the years 1669-1670, we have preserved for us nine letters
between Collins and Newton which give us some interesting details
on his occupation and character. 8 Collins was quick to press a friend¬
ship by asking for the solution of some problems, and by sending him
a copy of the new Kinkhuysen’s Algebra. Newton made some notes
upon it, at his leisure, and solved approximately the annuity problem:
“To know at what rate (N per cent) an annuity of B is purchased for
thirty-one years at the price A.” But when he found that Collins
wished him to revise the book, he answered that, as it was only a
moderately useful one, he did not care to do more than to review it
and to point out where it was amiss or defective.

News travelled slowly in those days and apparently Newton did
not learn until a year later that Hooke had made light of his dis¬
covery of the reflecting telescope, and had claimed to have antedated
the invention by several years. At least I cannot account for the
contents and date of the following letter in any other way.

8 Macclesfield, Vol. II, pp. 281-308.

142

ISAAC NEWTON

Newton to Collins

gj r Feb. 18, 1669/70.

Two days since, I received yours and Mr. Dary’s letter with a
book, for which I thank Mr. Dary, and have, here enclosed, sent him
my thoughts of what he desired. That solution of the annuity prob¬
lem if it will be of any use, you have my leave to insert it into the
Philosophical Transactions, so it be without my name to it. For l
see not what there is desirable in public esteem, were 1 able to ac¬
quire and maintain it. It would perhaps increase my acquaintance,
the thing which 1 chiefly study to decline. Of that problem I could
give exacter solutions, but that I have no leisure at present for com¬
putations. I now see a way, too, how the aggregate of the terms
of musical progressions may be found, (much after the same man¬
ner,) by logarithms, but the calculation for finding out those rules
would be still more troublesome, and I shall rather stay till you
have leisure to do me the favour of communicating what you have
already composed on that subject.

Your much obliged servant,

I. Newton. 9

We have been led to believe that Newton’s distaste for publicity,
and his threats to abandon science, were caused by the persistent
and ignorant criticisms of his papers on light. But this letter was
written a year or more before he sent his first paper to the Royal
Society and yet it expresses his sentiments as strongly as he ever did
afterwards. The only reason that can be given for his disillusion¬
ment is that he may have heard, although it hardly seems probable,
that Hooke had made some extravagant claims.

A closer examination of Kinkhuysen’s Algebra had changed New¬
ton’s opinion of its value, and he now spent considerable time re¬
vising, and making additions to it. By July, 1670, the notes were
finished and sent to Collins. But he is very doubtful whether they
should be printed with the translation as he had changed and added
so much: “There remains but one thing more, and that’s about the
title-page, if you print these alterations, which I have made in the
author. For it may be esteemed unhandsome and injurious to
Kinkhuysen to father a book wholly upon him, which is so much
altered from what he had made it. But I think all will be safe, if

9 Macclesfield, Vol. II, p. 296. Italics mine.

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after the words, Nunc c Belgico Latine versa, be added, Et ab alio
authore locupletata or some other such note.” 10

Collins at once expressed his hearty thanks and wrote “I re¬
ceived yours with Kinkhuysen’s Introduction, and perceive you have
taken great pains, which, God willing, shall be inserted into the
translation and printed with it. Hereby you have much obliged the
young students of algebra, and the bookseller.” 11 He had not, as yet,
become thoroughly acquainted with Newton’s reluctance to subject
himself to criticism and quite naturally ends his letter with the
query, “Why you should desire to have your name unmentioned I
see not; but if it be your will and command so to have it, it shall be
observed.”

Two other letters passed between them in the same month. New¬
ton’s thoughts had turned to expanding his notes on algebra into
a book of his own, and he asked for their return. This was exactly
what Collins desired, and he returned the manuscript with the
handsome and neat compliment that his “pains will be acceptable
to some very eminent grandees of the Royal Society, who must be
acquainted therewith” as he considers him more likely than any
man he knows to oblige the republic of learning. 12

The answer to Collins’s letter was delayed till the end of Septem¬
ber, as Newton was waiting for Dr. Barrow’s return from London
that he might consult his library on some matters connected with the
solution of cubic equations. A passage in this letter is worth quoting
at length. It shows, in his own words, the early trend of his mind
to avoid particular solutions, and to meditate on a subject till he had
arrived at a general synthesis which would embrace a whole category
of problems. This trait of mind accounts, in part, for the breadth of
the work which he did publish; but it also accounts for the fact that,
since the boundaries of his thoughts continually widened, he never
felt satisfied that his work should be published till he had been
teased by others to end his speculations. The passage is as follows:
“I sometimes thought to have set upon writing a complete introduc¬
tion to algebra, being chiefly moved to it by this, that some things
I had inserted into Kinkhuysen were not so congruous as I could
have wished to his manner of writing. Thus having composed
something pretty largely about reducing problems to an equation,
when I came to consider his examples, (which make the fourth part

10 Macclesfield, Vol. II, p. 298. 11 Ibid., VoL II, p. 299.

12 Macclesfield, Vol. II, p. 303.

144

ISAAC NEWTON

of his book,) I found most of them solved, not by any general
analytical method, but by particular and contingent inventions,
which, though many times more concise than a general method
would allow, yet, in my judgement, are less proper to instruct a
learner, as acrostics, and such kind of artificial poetry, though never
so excellent, would be but improper examples to instruct one that
aims at Ovidian poetry. But considering that, by reason of several
divertisements, I should be so long in doing it as to tire your patience
with expectation, and also that, there being several introductions to
Algebra already published, 1 might thereby gain the esteem of one
ambitious among the crowd to have my scribbles printed, I have
chosen rather to let it pass, without much altering what I sent you
before.” 13

Newton passed the year, 1671, in his study, not leaving Cambridge
except for a short visit to the country, probably Woolsthorpe, on busi¬
ness from 17 April to n May. He had finally been persuaded by Col¬
lins to publish some of his work under his own name and commenced
the preparation of twenty lectures on light for the press; but, before
they were ready, he became involved in the long controversy which
followed from his discovery of the composition of light and he
abandoned the project in disgust. He also decided to publish his
papers on infinite series, including his new method of the fluxions,
but this book also was never finished. It first appeared in 1736, in
Colson’s translation, with the title of The Method of Fluxions and
Infinite Series. Pemberton tells us that he induced Newton “to let
it go abroad. I had examined all the calculations and prepared part
of the figures; but as the latter part of the treatise had never been
finished, he was about letting me have other papers in order to
supply what was wanting. But his death put a stop to that design.” 14
Horsley included it in his edition of Newton’s Works under the title
of Geometria Analytica.

Newton to Collins

(London)

Sir, July 20, 1671.

I purposed to have given you a visit at the late solemnity of our
Chancellor’s creation; but I was prevented in that journey by the

13 Macclesfield, Vol., II, p. 307. Italics mine.

14 Pemberton’s View of Newton’s Philosophy, Lond., 1728. Preface.

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sudden surprisal of a fit of sickness, which not long after, (God be
thanked,) I again recovered of. And since I am prevented from a
verbal acknowledgement of your undeserved favours, I must be yet
contented to do it in writing. In which respect I find, by your last
letter, that I am still become more your debtor, both for the care you
take about my concerns, and for Borellius De Motionibus. But for
Borellius I beg that I may be accountable to you at our next meeting,
and that you would not, for the future, put yourself to the like
trouble in sending any more books. I shall take it for a great favour,
if in your letters you will only inform me of the names of the best
of those books which newly come forth.

The last winter I reviewed the Introduction [Kinkhuysen], and
made some few additions to it. And, partly upon Dr. Barrow’s
instigation, I began to new methodise the discourse of infinite series,
designing to illustrate it with such problems as may (some of them
perhaps) be more acceptable than the invention itself of working
by such series. But being suddenly diverted by some business in the
country, I have not yet had leisure to return to those thoughts, and
I fear I shall not before winter. But since you inform me there needs
no haste, I hope I may get into the humour of completing them be¬
fore the impression of the Introduction, because, if I must help to
fill up its titlepage, I had rather annex something, which I may call
my own, and which may be acceptable to artists, as well as the other
to tiros.

Farewell,

Your most obliged servitor,

I. Newton. 15

Elated by the performance of his first little telescope, Newton spent
much time in the autumn improving his method of polishing metal¬
lic mirrors and, in December, sent a new and better instrument to
the Royal Society where it is still displayed amongst its treasures. We
know about the instrument’s reception, and that it led to his nomina¬
tion for membership by Bishop Ward. 16 At the meeting of n Jan¬
uary, 1671/2 the brief statement was recorded, “Mr. Isaac Newton
was elected.” The fame of his telescope soon spread to the continent
and, in a book of this period, he is called an Artifex quidam Anglus

15 Macclesfield, Vol. II, p. 308. 16 Cf. Chap. Ill, p. 70 seq.

146

ISAAC NEWTON

nomine Newton, a title which well illustrates the fact that experi¬
mental science was not then rated as a learned profession.

An anecdote, if authentic, which appeared in The Gentleman s
Magazine, gives a picture of Newton’s truthfulness and inexperience
in worldly affairs: “One of Sir I. Newton’s philosophical friends
abroad had sent him a curious prism, which was taken to the Cus¬
tom-house, and was at that time a scarce commodity in this king¬
dom. Sir Isaac, laying claim to it, was asked by the officers what the
value of the glass was, that they might accordingly regulate the duty.
The great Newton, whose business was more with the universe than
with duties and drawbacks, and who rated the prism according to
his own idea of its use and excellence, answered ‘That the value was
so great, that he could not ascertain it.’ Being again pressed to set
some fixed estimate upon it, he persisted in his reply, ‘That he could
not say what it was worth, for that the value was inestimable.’ The
honest Custom-house officers accordingly took him at his word, and
made him pay a most exorbitant duty for the prism, which he might
have taken away upon only paying a rate according to the weight of
the glass!!” 17 This story may be founded on a conversation which
Dr. Stukeley reports as having taken place in 1721. “He showed
us [Halley and Stukeley] at that time the famous Huygenian glass
lens of 170 ft. radius which he had lately bought and since presented
to the Royal Society. He complained of the custom-house officers
making him pay £20 for the duty. He bought soon after, the great
Maypole set up in the Strand and had it carried to Wanstead for
Mr. Pound to use this glass upon, in astronomical observations.” 18

This year may be regarded as an important one in Newton’s life.
His paper on infinite series, and his general solution for finding the
area subtended by curved lines, had been circulated by Collins. It
was recognised by mathematicians that a general solution of the
most important problem of the day had been found and Newton be¬
came a marked man. The veteran Wallis wrote to Collins that he
thought it would be better for Mr. Newton to “publish what he hath
as a treatise of his own, rather than by way of notes on him [Kink-
huysen].” And again, “I would very fain that Mr. Hooke and Mr.
Newton v/ould set themselves in earnest for promoting the designs
about telescopes, that others may not steal from us what our nation
invents, only for our neglect to publish them ourselves.” So also

17 Weld, History of the Royal Society, Vol. I, p. 238.

18 Stukeley’s Mem. to Mead, Ports. Coll., File Add 4007.C.U,

TRINITY COLLEGE

147

James Gregory and Richard Towneley urged Collins to use his in¬
fluence to get these discoveries into print.

The Royal Society had been aroused to the keenest enthusiasm by
the little telescope which had been sent to them, and by the grasp
the young man had shown of the principles of light and lenses.
Newton had, at once, shown himself to be the peer of Descartes,
Hooke, and Huygens. The Secretary, Henry Oldenburg, was di¬
rected to thank him and did so in the following flattering terms: “It
[the telescope] having been considered, and examined here by some
of the most eminent in optical science and practice, and applauded
by them, they think it necessary to use some means to secure this
invention from the usurpation of foreigners. And they request me to
send a description of the instrument in a solemn letter to Paris to
Mr. Huygens, thereby to prevent the arrogation of such strangers.”

There is not the least doubt but that Newton was genuinely sur¬
prised and gratified by this reception of what he had looked upon
as the exercises and diversions of his youth. His surprise has gen¬
erally been ascribed to his modesty and diffidence. But it is far more
likely that he felt they were mere preliminary sketches for the great
problems which were ripening in his mind. If these slight things
would attract attention, what might not he expect from his medita¬
tions on the nature of light and the cosmogony ? His early letters to
Oldenburg in January and February, 1672, indicate clearly his atti¬
tude. Extracts from these letters have already been given. 19 In them
he mentioned his new discoveries in light as a matter really of impor¬
tance and hoped to show his gratitude for the honour of his election
by submitting other papers. Not only was he anxious to establish
cordial and ingenuous relations with members of the Society, but he
wished to have the advice of Oldenburg about the form of his com¬
munications.

Newton to Oldenburg

c: Jan. 29, Cambridge, 1671/2.

The publishing a description of the telescope in the Transactions
I wholly leave to your pleasure, being willing to submit my private
considerations in any thing that may be thought of public concern¬
ment. I have sent you, by the bearer, John Stiles, 40s for admission

19 Cf. Chapter III, p. 71 seq.

148

ISAAC NEWTON

money: and I hope I shall get some spare hours to send you also
suddenly that account, which I promised in my last letter. In the
mean time I rest

your very faithful servant,

I. Newton. 20

During March, Newton wrote four letters to Oldenburg giving
further particulars about his telescope and directions how to make
the necessary mirrors; he further reported that one of the Fellows of
the College was busy making another telescope.

But, these amicable feelings were not destined to endure. Huygens
and Hooke had stiffened in their objections to the new doctrine, and
a new critic had appeared in the person of Fr. Pardies of Paris. The
scientific world, also, was beginning to take sides in the controversy.
On April 9, James Gregory wrote to Collins: “I was exceedingly
surprised with these experiments of Mr. Newton; they will cause
great changes throughout all the body of natural philosophy, by all
appearance, if the matter of fact be true, which I have no ground to
question. I would gladly see what Mr. Hooke can say against the
doctrine raised upon them, and am most willing to be at all the
charges for the Transactions containing that debate, if you will be
pleased to send them to me.”" 1 But Flamsteed, the astronomer royal,
aligned himself against the theory and wrote to Collins: “I have
perused Mr. Newton’s letter concerning colours, but cannot think
them to proceed from difform rays, capable of different refrac¬
tions.” 22

In,addition to his burden of correspondence, Newton was still try¬
ing to find time to prepare other work for the press. We learn from
a letter of Collins, written to him on April 30: “Dr. Barrow informed
me you were busy in enlarging your general method of infinite
series, or quadratures, and in preparing twenty Dioptric lectures for
the press, and lately meeting with Mr. Jonas Moore, he informed
me that he heard you had something at the press in Cambridge, pos¬
sibly about the same argument: . . .” He also expressed his pleasure
that Newton had been elected a member of the Royal Society, but
was chagrined to learn that he is expected to pay dues which should
not be required of one who is so fitted “to enrich learning with your
excellent contemplations about the same.” 23

20 Macclesfield, II, p. 316.

22 Ibid., II, p. 134.

21 Ibid., II, p. 237.
23 Ibid., II, p. 319.

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149

Newton to Collins

Sir, Cambridge, May 25, 1672.

This day fortnight I received your letter accompanied with part of
the Remains of Mr. Horrox, two tracts of Honorato Fabri, and four
or five copies of a Synopsis of Mr. Kersey’s Algebra. For these and
Dr. Wallis’s Mechanics, together with many other civilities, I must
acknowledge your obligingness and affection to me, and shall be
ever ready to testify as much. Nor is your mathematical intelligence
less grateful; for I am very glad that Dr. Barrow’s book is abroad,
and that the world will enjoy the writings of the excellent astron¬
omers Mr. Horrox and Hevelius, and those complete mathematicians
M. Huygens and Slusius.

Your kindness to me also in proffering to promote the edition of
my lectures, which Dr. Barrow told you of, I reckon amongst the
greatest, considering the multitude of business, in which you are in¬
volved; but I have now determined otherwise of them, finding al¬
ready, by that little use I have made of the press, that I shall not
enjoy my former serene liberty till I have done with it, which I hope
will be so soon as I have made good what is already extant on my
account. Yet I may possibly complete the discourse of resolving
problems by infinite series, of which I wrote the better half the last
Christmas with intention that it should accompany my Lectures, but
it proves larger than I expected, and is not yet finished.

The book here in the press is Varenius his Geography, for which
I have described schemes, and I suppose it will be finished about six
weeks hence. The additions to Kinkhuysen’s Algebra I have long
since augmented with what I intended, and particularly with a dis¬
course concerning invention, or the way of bringing problems to
an equation; and those are at your command. If you have not deter¬
mined any thing about them, I may possibly hereafter review them,
and print them with the discourse concerning infinite series.

I take much satisfaction in being a member of that honourable
body the Royal Society; and could be glad of doing any thing which
might deserve it; which makes me a little troubled to find myself
cut short of that freedom of communication, which I hoped to en¬
joy, but cannot any longer without giving offence to some persons
whom I have ever respected. But it is no matter, since it was not for
my own sake or advantage that I should have used that free¬
dom. . . .

150

ISAAC NEWTON

For my tardiness in returning you this answer I have no excuse,
but that I staid four or five days, in hopes to send you some of those
subscriptions, and being intent upon the duty of this term, the time
slipped on faster than I was aware of. But I promise myself, by your
so much testified friendship, that you will pardon it, and believe that

I think myself really u r 111.

1 J your most obliged debtor,

I. Newton. 24

Edleston records an anecdote which if, as is probable, it refers to
the action between the English and Dutch fleets in Southwold Bay
on the 28th of May, shows Newton’s great acuteness of hearing and
observation: “There is a traditional story at Cambridge . . . that
Sir Isaac Newton came into the hall of Trinity College and told the
other fellows that there had been an action just then between the
Dutch and English, and that the latter had the worst of it. Being
asked how he came by his knowledge, he said that being in the
observatory [should be the great gateway], he heard the report of a
great firing of cannon, such as could only be between two great
fleets, and that as the noise grew louder and louder he concluded
that they drew nearer to our coasts and consequently that we had the
worst of it, which the event verified.” 25

Early in June, he wrote a long letter to Oldenburg to be trans¬
mitted to Pardies, explaining more fully his experiments in light.
And he soon had the pleasure of an answer that this more detailed
description of his work had fully satisfied Pardies, who now un¬
reservedly accepted the conclusions and had no further criticism to
make. During the controversy which followed, Newton vacillated
between scorn for the obtuseness of his critics, who seemed to him
unable to recognise that his work was a permanent contribution to
knowledge which could be disproved only by other experimentation
and not by speculation, and a hopeless feeling that however carefully
he might express himself no one would take the trouble to think
before making rash objections. In a mood for conciliation he wrote

24 Macclesfield, Vol. II, p. 321.—It is clear from this letter, and from one given later,
that Newton believed there was a cabal formed against him in the Royal Society by Hooke
which deliberately tried to prevent his work from receiving a just consideration. From the
sources at my disposal which unfortunately do not include the private memoranda of the
Society, his suspicion was without foundation.—One can but wonder when he acquired the
knowledge to lecture on geography as we know he did, or when he found time to under¬
take so laborious a task as preparing such a book for the press.

25 Edleston, p. xlvii.

TRINITY COLLEGE

I 5 i

to Oldenburg to revise his recent letters and to soften any expres¬
sions which might cause offense. At such times, he shows himself
as one would wish so great a man always to be, patient and con¬
siderate.

Newton to Oldenburg

gr. June 11 th , 1672.

I have sent you my Answers to M r Hook & P. Pardies, w ch I hope
will bring with y m y* satisfaction w ch I promised. And as there is
nothing in M r Hooks Considerations w th w ch I am not well con¬
tented, so I presume there is as little in mine w ch he can excep
against, since you will easily see that I have industriously avoyded
y e intermixing of oblique & glancing expressions in my discourse.
So y t I hope it will be needlesse to trouble the R. Society to adjust
matters. However if there should possibly be any thing esteemed
of y* kind, I desire it may be interpreted candidly & with respect to
the contents of M r Hooks Considerations, & I shall readily give way
to y e mitigation of whatsoever y e heads of y e R. Society shall esteem
personall. And concerning my former Answer to P. Pardies, I
resigne to you y e same liberty w ch he hath done for his Objections,
of mollifying any expressions that may have a shew of harshnesse.

Yo r Servant

These L Newton.

To Henry Oldenburg Esq: at his house

about y e middle of y e old Pall-maile
in Westminster London, 26

Shortly after writing this letter, Newton left Cambridge for a
month of rest and visiting. He first went into Bedfordshire and
then home, to Woolsthorpe, where he always regained his com¬
posure. Oldenburg continued to press him to keep up the attempt
to satisfy his critics, but Newton wisely wrote him that he would
wait till he had had time to prepare a convincing and temperate
reply. After a short stay at those places, he paid a visit of almost a
month at the house of Mrs. Arundell, in Stoke Park, Northampton-

28 Edleston, p. 248.—A curious instance of the license in spelling in those days is shown
by the fact that Newton spelled and capitalised “Pall-Mall” in as many different ways as
the sound of the words could suggest to an ingenious mind. I have noted, without much
attention, five forms. Although I have generally transcribed most of the letters into modern
spelling, I have left this as Newton wrote it. His letters show that he wrote hurriedly and
frequently dropped words and letters.

152

ISAAC NEWTON

shire. While there, he wrote to Oldenburg that excellent statement
of the scientific method which should, I think, be learned and fol¬
lowed by every man of science:

“In the mean while give me leave to insinuate that I cannot think
it effectual for determining truth to examine the several ways, by
which phenomena may be explained, unless where there can be
a perfect enumeration of all those ways. You know the proper
method for enquiring after the properties of things is to deduce them
from experiments: and I told you that the theory, which I pro¬
pounded, was evinced to me, not by inferring ’tis thus because not
otherwise; that is, not by deducing it only from a confutation of
contrary suppositions, but by deriving it from experiments conclud¬
ing positively and directly. The way therefore to examine it is by
considering the experiments, which I propound, do prove those
parts of the theory, to which they are applied, or by prosecuting
other experiments, which the theory may suggest for its examina¬
tion. 27

He also asked Oldenburg to keep him informed about the prog¬
ress of the war with Holland, as he is “at a place where the quick
arrival of news is a rarity.” To Collins, he wrote to inform him
that he had finally decided not to publish his lectures on light and
was hesitating about the advisability of finishing his work on infinite
series. As soon as he returned to Cambridge he wrote again to him,
on July 30, that Varenius 28 was newly off the press, and he had sent
a complimentary copy by the university carrier, John Stiles. To¬
wards the end of the year, Dr. Barrow was appointed Master of
Trinity, and Newton expressed his pleasure in welcoming the return
of his patron and teacher in a letter to Collins in which he said that
no one rejoiced more than he did.

The years 1673 an d 1674 were a time of little incident. The
records of the Royal Society rarely mention Newton’s name. He

27 Macclesfield, Vol. II, p. 326.

28 Bernhardi Vareni Geographia generalis, in qua affectiones generales Telluris explican-
tur, summa cura quam plurimis in locis emendata, et XXXIII Schematibus novis, aere incisis,
una cum Tabb. aliquot quae desiderabantur aucta et illustrata., Ab Isaaco Newton Math.
Prof. Lucasiano apud Cantabrigiensis.. Cantabrigiae 1672. “The first edition had appeared
in Holland in 1650, and was considered the best book on geography of that time. Another
Cambridge edition, with Newton as editor, came out in 1681. A third edition, in English
translation, was issued after the death of Newton, in 1736, in which the translator re¬
marked: ‘The reason why this great man took so much care in correcting and publishing
our author, was because he thought him necessary to be read by the audience while he
was delivering lectures upon the same subject from the Lucasian chair.’ ” Sir Isaac New¬
ton, Baltimore, 1928, p. 168. This is, I think, the only reference to the fact that he delivered
lectures on geography.

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153

wrote only a few letters on light, and these were sent to Huygens
who had become dissatisfied with his own attempt to include the
new work in the wave theory of light.

Early in March, 1673, there occurred a contest for power between
the Heads of the Colleges and the Senate over the appointment of
Public Orator. In spite of the effort of the Chancellor to effect a
compromise and of a protest on the morning of the election by
a large number of the Senate, amongst whose names was that of
Newton, the Heads gained the day and installed their choice.

Newton, apparently, this year became apprehensive about his in¬
come. In the ordinary course of events, his fellowship would expire
in the autumn of 1675. He had been advised to take orders so that
he might continue as Fellow, but he finally refused on the ground
that he could give better service to religion out of the church. On
February 14, a law-fellowship became vacant which was open to
lay members of the College. The story has come down to us “that
Newton and Robert Uvedale were candidates for the fellowship in
question; and that Mr. Barrow, who had been admitted Master of
Trinity on February 27, decided it in favour of Mr. Uvedale, saying
that Mr. Uvedale and Mr. Newton being equal in literary attain¬
ments, he must give the fellowship to Mr. Uvedale as senior/’ 29
Brewster makes much of this story to excite sympathy for Newton
in order to show that he was a much neglected young man. But, as
Edleston remarks, since this fellowship required the holder “operam
dare juri civili” its duties could hardly be undertaken by a professor
of mathematics. Brewster thought this was a mere technicality as
such fellowships have frequently been occupied by men who had no
qualifications for the law; but Barrow and Newton were the type
of men who would take their word and their work seriously. It is
simply absurd to put in Barrow’s mouth that he thought Newton
and Uvedale equal in attainments. As the story originated with a
great-grandson of Robert Uvedale, we can assign it to a family tra¬
dition that Uvedale was appointed to a lay-fellowship and that New¬
ton had desired it.

Rightly or wrongly, Newton was worried about his living; how¬
ever, even if he had lost his fellowship, it will be shown later that
he was not in any serious difficulties. In my opinion his sudden
decision to resign from the Royal Society should not be laid to
poverty as has been very generally assumed; but he had been dis-

29 Edleston, p. xlviiL

*54

ISAAC NEWTON

illusioned, he had never as yet attended a meeting and was con¬
stantly fretted by the rumours Oldenburg sent him that he was
criticised and attacked by Hooke and his proteges. At any rate he
startled Oldenburg by sending him the following letter.

Newton to Oldenburg

g* r Cambridge, March 8, 1672/3.

I received both your letters, and thank you for Hecker’s Mer-
curius in Sole. As for M. Huygens’ observations, I conceive they are
but the abstract of a private letter sent to you, and therefore con¬
cern not me to take notice of them. But yet if he expect an answer,
and intends that this should be made public, I will return you my
thoughts upon them, if you please to send me the original letter,
and procure from M. Huygens that I may have liberty to publish
what passeth between us, if occasion be.

Sir, I desire that you will procure that I may be put out from
being any longer Fellow of the Royal Society: for though I honour
that body, yet since I see I shall neither profit them, nor (by reason
of this distance) can partake of the advantage of their assemblies,
I desire to withdraw. If you please to do me this favour you will
oblige

your humble servant,

I. Newton.

P. S. I have presumed to put you once more to the trouble of
receiving my quarterly duty as Fellow of the Royal Society. At next
Lady-day I am behindhand for half a year, and have therefore sent
you 1//6s. by John Stiles. I hope you will excuse this trouble, it
being the last. I shall be henceforth absent from Cambridge for
about a month. 30

Oldenburg was much disturbed by this letter and at the idea of
the Society losing so valuable a member; perhaps, also, he was cha¬
grined by the consciousness that he may have been partly responsi¬
ble. He answered at once to express surprise “at his resigning for no
other cause than his distance, which he knew as well at the time of
his election. Offering withal my endeavour to take from him the
trouble of sending hither his quarterly payments without any reflec¬
tion.”

30 Macclesfield, II, p. 348.

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155

After sending this letter, Newton left Cambridge, probably for
a short visit home, and did not return until the 1st of April. His
correspondence with Collins was mostly as a go-between with fames
Gregory over the merits of their forms of reflecting telescopes. Col¬
lins so managed it that Gregory became a warm friend and admirer
of Newton, and there was no break in their friendship. Newton
states in one of these letters that he was unable to read French with¬
out the continual use of a dictionary.

He also confides to Collins his troubles with the Royal Society in
a manner which I think makes it certain that the payment of dues was
an excuse for the true reason. He wrote: “Concerning the expenses
of being a member of the R. S. I suppose there hath been done me
no unkindness, for I met with nothing in that kind besides my
expectations. But 1 would wish l had met with no rudeness in some
other things. And therefore I hope you will not think it strange, if,
to prevent accidents of that nature for the future, I decline that con¬
versation which hath occasioned what is past. I hope this, whatever
it may make me appear to others, will not diminish your friendship
to me.” 31

Late in the year Gregory went to London and, on his way back to
Scotland, stopped in Cambridge to pay Newton a visit during which
the two indulged in long and intimate talks on telescopes, mirrors,
and mathematics.

Newton passed almost the entire year, 1674, in Cambridge. There
is nothing to record accept the final flare up over his experiments on
light. This time, the objection came from the Liegeois professors,
who were pompous in their conceit and exasperating in their dull¬
ness; nor did Oldenburg help matters, for he could not understand
that they were not critics in the same class with Hooke and Huygens,
and he continued to pester his friend with urgent requests to defend
himself instead of letting their opinions die from their own foolish¬
ness. The discussion dragged on for two years more and ended with
the death of Oldenburg.

Added to the irritation which the long-drawn-out and, of late,
futile controversy on light had engendered, there had arisen a new
injury to his feelings, for Oldenburg had hinted that it would be
unnecessary for him to resign from the Royal Society as a promise
of experiments and discourses from him would be accepted in lieu

31 Macclesfield, II, p. 360.—The word “conversation” was used to express any social
intercourse. Its use in that sense will be an important matter in an incident in his later life.
Italics mine.

156

ISAAC NEWTON

of the payment of dues. In this frame of mind he wrote, in 1674,
that he wished to be excused from giving any discourses, or demon¬
strations, to the Society as he was seldom in London. 32 Though he
did not insist on his resignation being accepted, he for many years
rarely attended meetings. It was not till the Society received his
Pnncipia with such enthusiasm that he recovered from his wounded
feelings; and so long as Hooke lived, Newton showed but little in¬
terest in its affairs and had no place in its councils.

32 For the full text of the letter, cf. Chap. IV.

CHAPTER VI

ALCHEMY AND CHEMISTRY. HIS PERSONAL LIFE. RELA¬
TIONS WITH HOOKE. EARLY MATHEMATICAL WORK.
INVENTION OF CALCULUS. CORRESPONDENCE

WITH LEIBNIZ

1674-1676

T owards the end of the year, 1675, Collins made the casual re¬
mark in a letter to Gregory: “Mr. Newton, I have not writ to
or seen these eleven or twelve months, not troubling him as
being intent upon chemical studies and practices, and both he and
Dr. Barrow beginning to think mathematical speculations to grow at
least dry, if not somewhat barren.” 1 As has been remarked before,
Newton suffered from irritation and depression when circumstances
compelled him to confine himself to mathematical, or speculative,
work and he then sought solace in what we should now call experi¬
mental science. The need for such diversion was pressing upon him;
he was weary of the contentions of men and the criticism of work
which afforded him no interest.

In comparison with his other work, what Newton achieved in
chemistry has been rather slighted. While it is true that he made no
striking discoveries or enlarged the knowledge of chemical action,
one has merely to glance through the manuscripts of the Portsmouth
Collection to be convinced that he was a master of the subject. He
left a mass of notes and data relating to the experiments he had tried.
According to his habit, he was indefatigable in making notes in his
common-place books and draughts of attempts to ally molecular
forces with gravitational attraction of bodies. His own books were
annotated on the margins and passages marked by his customary
habit of folding the corners of the pages; and he frequently borrowed
from the University Library. An examination of his own library
shows a comprehensive collection of books on chemistry and the very
large proportion of works on alchemy and magic is significant of his
interest. 2 Since his efforts were concentrated on finding a general

1 Macclesfield, Vol. II, p. 280. 2 Cf. R. de Villamil, Newton: The Man, London, 1932.

157

158

ISAAC NEWTON

synthesis of chemical combinations and on the transmutation of the
elements which we now contemptuously class as alchemy, it is prob¬
able that having accomplished neither, he did not think it advisable
to publish his disconnected and tentative results.

We are justified in saying that Newton’s interest in chemistry be¬
gan with his boyish days in Clark’s apothecary shop; his first note¬
book preserved in the Morgan Library is largely filled with recipes
referring more or less to the subject. During the thirty-five years he
lived in Cambridge he experimented intermittently, but with an al¬
most passionate energy, in the college room he had fitted as a
laboratory. In London, after he had given up all other scientific
work, he still found pleasure in the chemical problems relating to
metals and alloys which were involved in the operations of the Mint.
Humphrey Newton of Grantham, who served for some years as his
assistant and amanuensis, has left us this interesting description of
Newton’s method of relaxation when fatigued with the composition
of the Pnncipia. “About six weeks at spring, and six at the fall, the
fire in the laboratory scarcely went out, which was well furnished
with chemical materials as bodies, receivers, heads, crucibles, etc.,
which was [sic] made very little use of, the crucibles excepted, in
which he fused his metals; he would sometimes, tho’ very seldom,
look into an old mouldy book which lay in his laboratory, I think it
was titled Agricola de Metallis, the transmuting of metals being his
chief design, for which antimony was a great ingredient.” 3

The fact of the matter is, Newton was an alchemist, and his
major interest in chemistry, in his earlier years, centred in the pos¬
sibility of transmuting metals. He begged his youthful friend, Aston,
in the letter previously quoted, 4 to find out all he could on the sub¬
ject during his travels and not to be too scrupulous in his method
of enquiry. Humphrey Newton found him absorbed in the search
in 1685, an d still later in life he carried on a correspondence about it
with Locke and Boyle. There was a mystical strain in his character
which has been quite overlooked. It showed itself not only in his
persistent reading of the esoteric formulae of the alchemists, but also
in his sympathy for the philosophy of the Cambridge Platonists and
in his extended interpretations of the prophecies of the Books of
Daniel and of the Revelation. Nor did his enquiry stop at these
bounds, there is evidence that he studied the writings of Jacob

^Portsmouth Collection. Letter of H. Newton to Conduitt.—This work and others of
Agncola are to be found in the catalogue of his library.

4 Cf. Chap. II, p. 49.

CHEMISTRY AND MATHEMATICS

159

Boehme and became, more or less, a follower of the mystical shoe¬
maker. “The Rev. Mr. Law has stated that there were found among
Sir Isaac’s papers large extracts out of Jacob Boehme’s works, written
with his own hand, and that he had learned from undoubted
authority, that in a former part of his life he was led into a search of
the philosopher’s tincture from the same author.” 5 There can be no
doubt that he not only seriously sought the transmutation of metals
into gold and the universal panacea for disease and old age, but also
believed them to be the chief goal of the chemist.

Because of our facile identification of alchemists with charlatans
and prostituters of pure science for the sake of wealth, Newton’s
eulogists, although they must admit that he was an ardent adept,
attempt to explain his motive as only a desire to expose the errors of
those “great pretenders” of the Hermetic philosophy as he once
termed them. 6 Why should Newton not be an alchemist? All his
contemporaries, even Boyle, Locke, and Hooke were, and if he de¬
sired to study the composition of bodies, he would without hesitation

5 Brewster, Vol. II, p. 371. Boehme’s works were in his library.

6 Cf. Brewster, Vol. II, p. 374. “The alchemy of Boyle, Newton, and Locke cannot be
thus characterised [as commencing in fraud and terminating in mysticism]. The ambition
neither of wealth nor of praise prompted their studies, and we may safely say that a love of
truth alone, a desire to make new discoveries in chemistry, and a wish to test the extraor¬
dinary pretensions of their predecessors and their contemporaries, were the only motives by
which they were actuated. In so far as Newton’s enquiries were limited to the transmutation
and multiplication of metals, and even to the discovery of the universal tincture, we may find
some apology for his researches; but we cannot understand how a mind of such power, and
so nobly occupied with the abstractions of geometry, and the study of the material world,
could stoop to be even the copyist of the most contemptible alchemical poetry, and the an¬
notator of a work [by Agricola], the obvious production of a fool and a knave.”—Brewster
obviously did not know the reputation of that author, and it is a gross injustice to class
alchemists as knaves and fools. The assertion that Newton was engaged in alchemical re¬
search and studied its treatises only in order “to test the extraordinary pretensions” of the
alchemists rests on a single statement in a letter in which he says (see infra, Chap. VI,
p. 162), “there being other things besides the transmutations of metals (if those great pre¬
tenders brag not) which none but they understand.” Brewster evidently thought that he used
the word “pretender” to mean one suspected of fraud and falsehood. But Newton used it to
characterise one who earnestly sought to obtain knowledge. Its restriction to a false claimant
came into the language only after it had been applied by the Whigs to the claims of the son
of James II in order to throw discredit on their legitimate claims. The pitfalls of language
which await the historian of the seventeenth century are many. For instance one of the most
recent writers on Newton makes the following remarkable deduction. Newton once, when
indulging in an extravagant speculation, checks himself with the simple statement, “I am not
satisfied about it for want of Experiments.” The essayist makes this delightful comment,
“Note the capital E. Do we not have here a glowing example of Newton the experimental
natural philosopher?” (Sir Isaac Newton, 7727-/927, p. 222. Essay by Professor Lyman
Newell.) One can but believe that the essayist was quite unacquainted with the laxity of
capitalisation and spelling of Newton and of all writers of that century. If he had con¬
sidered even one example he would have drawn no inferences from a capital E. I claim the
highest admiration for Newton, but I trust that I may not fall under the hypnotic spell which
seems to be the fate of those who discuss his great personality.

i6o

ISAAC NEWTON

class himself as one of them. Alchemy, in name, is probably the
Arabic translation of the Greek word to mix or to fuse, and it was
applied to designate all the known chemical processes; the new term,
chemistry, was but just beginning to come into use.

During the Middle Ages, and well down into the seventeenth cen¬
tury, all matter was believed to be composed of the four elementary
substances or essences,—earth, water, air, and hre,—combined in dif¬
ferent proportions and actuated by the qualities of heat and cold,
dryness and moisture. Thus, there was every reason for the convic¬
tion of alchemists that proper chemical and physical reagents would
alter the relative proportions of those elements in any given com¬
pound and so change one substance into another. For example, al¬
chemists considered gold and lead to be compounds of the four ele¬
ments in different proportions and therefore could be transmuted
by proper chemical reagents; on the other hand, chemists during the
nineteenth century confidently declared that gold and lead were two
amongst ninety-odd immutable elements which combined in vary-
ing proportions to form all other substances. It is difficult, in a scien¬
tific sense, to distinguish between the theories of alchemy and chem¬
istry, however greater the practical knowledge of what elementary
substances now may be. The certainty of the ideas of chemists of the
last century seemed to have been thoroughly established; this cer¬
tainty, however, no longer pertains to at least all of their elementary
substances, one of them, uranium, without artificial aid decomposes
into radium and it, in turn, into the element, lead. It is safe to say
that many chemists now assume there is but a single primary ele¬
ment, a protion of electricity,—as hypothetical as the primary ele¬
ments of alchemists; and they are diligently trying to transmute
what they formerly claimed to be fixed elements. Also, if we grant
the postulates of alchemists that the human body is composed of
the four classic elements and that illness, and even death, result from
a disturbance of their just balance, then it is a perfectly rational and
scientific conclusion that a chemical method, an elixir of life, might

be found which would restore their balance and be a cure for dis¬
ease and senility. 7

7 The emperor Diocletian “caused a diligent enquiry to be made ‘for all the ancient books
which treated of the admirable art of making gold and silver, and without pity committed
them to the flames; apprehensive, as we are assured, lest the opulence of the Egyptians should
inspire them with confidence to rebel against the empire.’ But if Diocletian had been con¬
vinced of the reality of that valuable art, far from extinguishing the memory, he would have
converted the operation of it to the benefit of the public revenue. It is much more likely that
his good sense discovered to him the folly of such magnificent pretensions, and that he was

CHEMISTRY AND MATHEMATICS

161

The mere fact that natural cupidity for health and wealth led
many alchemists to seek especially the philosopher’s stone and the
transmutation of lead into gold has nothing to do with the ques¬
tion. The difference between alchemy and chemistry is a difference
in time and experience rather than of concept or method. Is it
not one of the glories, and I venture to say the chief glory, of modern
chemistry that it has vastly increased our power and wealth ? Is not
radioactivity but the science of the transmutation of the elements?
There is a vast deal of nonsense talked about science for science sake,
just as there is about art for art’s sake. Newton, Boyle, and Locke
desired to apply their knowledge to obtain practical results, and
would have welcomed power and wealth as men of science do today.
Francis Bacon esteemed science only for its fruits. And it is a com¬
mentary on human blindness for anyone in this age, absorbed as it is
in the pursuit of mechanical power and with its ideals confused with
material welfare, complacently to apologise for Newton’s practical
tastes lest his scientific reputation be smirched. As he grew older,
he seems to have lost his faith in the practicability of transmutation.
At least, in his letters to Locke, he expressed a doubt that Boyle had
found an alchemical recipe and had kept it a secret for twenty years.

Boyle’s own ideas on alchemy and on science for science’s sake can
be given in his own words. For example, Boyle published a paper
in the Philosophical Transactions in 1675 on “An experimental Dis¬
course of Quicksilver growing hot with Gold.” In this paper he de¬
scribed how, “through God’s blessing, my trials afforded me positive
proof about the year 1652” and a preparation of mercury had been
found which when mixed with powdered gold made the mass be¬
come noticeably warm. In conclusion he states: “I will not so much
as affirm, that every mercury obtained by extraction, even from the
perfect metals themselves, must needs be more noble and fit, as al¬
chemists speak, for the philosophic utor\, than that, which common
mercury skilfully freed from its recrementitious [superfluous] and
heterogeneous parts, and richly impregnated with the subtle and
active one of congruous metals or minerals.” This discourse oc¬
casioned the following comment from Newton.

desirous of preserving the reason and fortunes of his subjects from the mischievous pursuit.
It may be remarked that these ancient books, so liberally ascribed to Pythagoras, to Solomon,
or to Hermes, were the pious frauds of more recent adepts. The Greeks were inattentive
either to the use or to the abuse of chemistry. In that immense register, where Pliny has de¬
posited the discoveries, the arts, and the errors of mankind, there is not the least mention of
the transmutation of metals; and the persecution of Diocletian is the first authentic event
in the history of alchymy.” Gibbon, Roman Empire, Chap. XIII.

162

ISAAC NEWTON

Newton to Oldenburg

Sir, Cambridge, April 26, 1676.

Yesterday I reading the two last Philosophical Transactions had the
opportunity to consider Mr. Boyle’s uncommon experiment about the
incalescence of gold and mercury . I believe the fingers of many will
itch to be at the knowledge of the preparation of such a mercury;
and for that end some will not be wanting to move for the publish¬
ing of it, by urging the good it may do in the world. But, in my
simple judgement, the noble author, since he has thought fit to re¬
veal himself so far, does prudently in being reserved in the rest.
Because the way by which mercury may be so impregnated, has been
thought fit to be concealed by others that have known it, and there¬
fore may possibly be an inlet to something more noble, not to be
communicated without immense damage to the world, if there
should be any verity in the Hermetic writers; therefore I question
not, but that the great wisdom of the noble author will sway him to
high silence, till he shall be resolved of what consequence the thing
may be, either by his own experience, or the judgement of some
other that thoroughly understands what he speaks about; that is, of
a true Hermetic philosopher, whose judgement (if there be any such)
would be more to be regarded in this point, than that of all the
world beside to the contrary, there being other things beside the
transmutation of metals (if those great pretenders brag not) which
none but they understand. Sir, because the author seems desirous of
the sense of others in this point, I have been so free as to shoot my
bolt; but pray keep this letter private to yourself.

Your servant,

Isaac Newton. 8

That Boyle did not have any contempt for the practical fruits of

science may be seen from an extract from a letter written towards
the close of his life.

Sir, Boyle to a Friend

To those that think it strange, that among my other experiments
about metals and minerals, I have not produced those gainful ones,

8 Boyle’s Works, Vol. ff, p. cv; and Macclesfield, Vol. II, p., 395. Italics mine.

CHEMISTRY AND MATHEMATICS

i6 3

that chemists call particulars, it may, I hope, suffice to represent, that
being a bachelor, and through God’s bounty furnished with a com¬
petent estate for a younger brother, and freed from any ambition to
leave my heirs rich, I had no need to pursue lucriferous experiments,
to which I so much preferred luciferous ones, that I had a kind of am¬
bition {which 1 now perceive to have been a vanity ) of being able to
say, that I cultivated chemistry with a disinterested mind, neither
seeking nor scarce caring for any other advantages by it, than those
of the improvement of my knowledge of nature, the gratifying the
curious and industrious, and the acquist of some useful helps to make
good and uncommon medicines. . . . But, however, since I find my¬
self now grown old, I think it time to comply with my former in¬
tentions to leave a kind of Hermetic legacy to the studious disciples
of that art, and to deliver candidly, in the annexed paper, some proc¬
esses chemical and medicinal, that are less simple and plain than
those barely luciferous ones I have been wont to affect, and of a
more difficult and elaborate kind than those I have hitherto pub¬
lished, and more of kin to the noblest Hermetic secrets, or, as Hel -
mont styles them, arcana majora. Sir,

Your most faithful and most humble servant,

Robert Boyle. 9

Hooke was so eager for money that he constantly dunned the Royal
Society for more salary and lived as a miser, that he might fill his
iron-bound chest: Newton was generous, but he was careful enough
to leave a large fortune at his death.

In spite of Newton’s interest and persistent work in chemistry, he
published only one strictly chemical paper. This work, De Natura
Acidorum, is only about two pages long and is a succession of specu¬
lations on chemical affinity rather than a detailed account of acids.
As it contains references to the Principia, it must be dated after
1685. If the reader be interested in Newton’s chemical work, he
should read carefully Queries 30 and 31 in the Optics, since he gives
in them his ideas on chemical affinity and the cause of chemical
action in a less technical form than elsewhere.

Query 30 is a veiled apology for the search for the transmutation
of metals. He pictures Nature as delighted with transmutations, and
gives examples to show that all bodies are composed of the same hard
particles which differ in nature only because of their arrangement and

9 Boyle’s Wor\s, Vol. I, p. exxx.

164

ISAAC NEWTON

their mutual forces of attraction. He even carried his belief in trans¬
mutability so far as to query whether gross bodies and light are not
convertible into one another.

Query 31 is a review of the general question whether all physical
and chemical phenomena, and perhaps even the phenomena of life
are not due to a mechanical attraction between all particles of mat¬
ter,—a generalisation from his discovery of gravitation. A few quota¬
tions from it will show the drift of his ideas:

Have not the small particles of bodies certain powers, virtues or
forces, by which they act at a distance, not only upon the rays of light
for reflecting, refracting and inflecting them, but also upon one an¬
other, for producing a great part of the phenomena of Nature? . . .
For Nature is very consonant and conformable to herself. Flow those
attractions may be performed, I do not here consider. What I call
attraction, may be performed by Impulse, or by some other means
unknown to me. I use that word here to signify only in general any
force by which bodies tend towards one another, whatsoever be the
cause. For we must learn, from the phenomena of Nature, what
bodies attract one another, and what are the laws and properties of
the attraction, before we enquire the cause by which the attraction
is performed. The attractions of gravity, magnetism and electricity,
reach to very sensible distances, and so have been observed by vulgar
eyes; and there may be others which reach to so small distances as
hitherto escape observation; and perhaps electrical attraction may
reach to such small distances, even without being excited by friction.”

For when salt of tartar runs per deliquiwtn, is not this done by an
attraction between the particles of the salt of tartar, and the particles
of water, which float in the air in the form of vapours? . . . When
salt of tartar per deliquium, being poured into the solution of any
metal, precipitates the metal, and makes it fall down to the bottom
of the liquor in the form of mud: does not this argue, that the acid
particles are attracted more strongly by the salt of tartar than by the
metal, and by the stronger attraction go from the metal to the salt
of tartar?”

The parts of all homogeneal hard bodies, which fully touch one
another, stick together very strongly. And for explaining how this
may be, some have invented hooked atoms [Democritus], which is
Pegging the question; and others tell us, that bodies are glued to¬
gether by rest [Descartes]; that is, by an occult quality, or rather by
nothing: and others, that they stick together by conspiring motions:;

CHEMISTRY AND MATHEMATICS

165

that is, relative rest amongst themselves. I had rather infer from
their cohesion, that their particles attract one another by some force,
which in immediate contact is exceeding strong, at small distances
performs the chemical operations above-mentioned, and reaches
not far from the particles with any sensible effect.”

“All bodies seem to be composed of hard particles: for otherwise

fluids would not congeal.”

“And thus Nature will be very conformable to herself, and very
simple; performing all the great motions of the heavenly bodies by
the attraction of gravity, which intercedes those bodies; and almost
all the small ones of their particles, by some other attractive and re¬
pelling powers, which intercede the particles.”

“And therefore that Nature may be lasting, the changes of cor¬
poreal things are to be placed only in the various separations, and
new associations, and motions of these permanent particles.

It seems quite evident that Newton found in chemistry the scien¬
tific work most congenial to his personal tastes and aptitude; it satis¬
fied best his fondness for working with tools and for experimenta¬
tion, and at the same time gave full play for his predilection for
wide generalisations. Though he performed a multitude of separate
experiments, they were done for his own satisfaction, and he saw no
reason for making them public. They would be of use to the world
only if, by them, he could arrive at some general and fundamental
principle of chemical action, such as he had found in the universal
force of attraction. Thus his eager enquiry in alchemy was for the
purpose of finding some essential substance, or quality in matter,
which by its variations would link together all chemical actions,
such as the postulates of inertia and attraction had in the physical
world. His successful synthesis in mechanics was made possible by
the work of his great predecessors, but he could find in chemistry no
such material. He certainly had pictured in his mind an atomic
theory in which the variety of elements was due to the geometrical
groupings of a universal atomic substance. He had gone even further
in that he queried whether the force which held together, and acted
on, those atomic groups were not the same attractive force which
bound the planets into a solar system; and he had also queried
whether chemical affinity were not a manifestation of electricity.
But to Newton, queries were not science till they were supported by
experimental demonstration. If the accumulation of chemical data
had permitted Newton to formulate the modern atomic theory, as it

166

ISAAC NEWTON

did Dalton, we may not know what would have been the history of
chemistry, but we can be certain that the intimate connection be¬
tween physics and chemistry would have been established much
earlier. Newton would not have advanced an atomic theory in the
simple and statistical form that it left Dalton’s hands. He would
surely have given it a dynamic basis, and have attempted to express
chemical forces by mathematical formulae. In fact, there is reliable
evidence that he had undertaken such a work. I found in the Ports -
mouth Collection the following memorandum by Stukeley: “He
wrote likewise a piece of chemistry, explaining the principles of
that mysterious art upon experimental and mathematical proofs and
he valued it much, but it was unluckily burnt in his laboratory which
casually took fire. He would never undertake that work again, a
loss much to be regretted.” 10

This brief survey of Newton’s chemical work will be closed by
quoting an estimate of it by Professor H. E. Armstrong: “Newton
; .. considering the operation of the force of residual affinity, which
is not only unexplained to the present day but rarely considered. In
his subsequent discussion of the interactions of acids and metals, and
of acids and salts, he is dealing with the subject of ordinary chemical
change. Speculation on these subjects to-day is not less vague than it
was in Newton’s time. Modifying his language but slightly, to reduce
it to modern terms, we can but realise that little advance has been
made in our understanding of the phenomena—although we have
an exact and abounding knowledge of fact which is astounding com¬
pared with that of Newton s day. We need a Newton with the
perspicacity to order our knowledge into a philosophy.” *

Professor Armstrong also points out that Newton, when he de¬
scribed the air as abounding “with acid vapours fit to provide fer¬
mentations,” 11 anticipated Lavoisier, and then ends with this dras¬
tic criticism of modern ideas and practice:

aT ^. ay ’ we have reduced the conception ‘Acid’ to the most misera¬
ble of dimensions—to a figment of the imagination, the lonely hy¬
drogen ion. Verily, is our ignorance far greater than that of Newton,
near two hundred years ago, because, having eyes to see and a vast

Though the statement adds another to the confusion of the Newtonian fires, I believe
it is correct as it occurs in Stukeley’s Memorandum to Mead, one of the most trustworthy

of Newton ^ 1 f ° Und * a S ° 1X1 3 draught o£ Fra S™ents of Conduitt’s intended Life

11 He means by fermentations all such oxidation processes as the rusting of metals, com¬
bustion, the heat from respiration, etc.

CHEMISTRY AND MATHEMATICS 167

mass of recorded fact to consider, we will take no notice of fact and
are but worshippers of faiths which have no secure basis ?

“Whether we study diamond, whether we study colour, whether
we study acids or other characters, we are always faced with this one
problem that which struck Newton’s attention, the problem of
chemical affinity. We now believe it to be electrical in its ongm.
Further it is impossible to go at present—the speculation thus far in¬
dulged in seems trivial in face of the complexities the subject presents.
We are told that the electron does everything but how it does any¬
thing we are not informed.

“We need, indeed, to follow Newton’s advice—to argue from
phenomena with less feigning of hypotheses and to deduce causes
more from effects. Never was superstition more rife in scientific
circles than it is to-day—the apostolic injunction, ‘Prove all things,
hold fast that which is true,’ is not practised, at least among chemists
and physicists. Above all, we need to clear our minds by argument,
if there be any left to argue, with reasonable attention to the facts.

It is time to turn to Newton’s personal affairs. We have been led
to believe that he was much worried during 1675 about his finances,
and the cause has been ascribed to the fact that, in the natural course
of events, his fellowship which he had held for seven years would
lapse in the coming autumn. If he was so worried, it was the only
time in his life of which we have any record; the probable loss of his
fellowship does not seem sufficient to have caused any acute anxiety.
The monetary value of a fellowship, apparently, was unusually small
at that time. The new Master of Trinity, Dr. Barrow, had just called
attention to the fact that, “a fellowship with us is now so poor that I
cannot think it worth holding by an ingenuous person upon terms
of so much scruple.” 13 While this statement is somewhat vague as
we may find it difficult to capitalise the scruples of an ingenuous
person, Edleston estimated the annual income of his fellowship to be
less than /'30. From the analysis of his income previously given,
he would still have, in addition to his free lodgings and dinners, ££>o
a year from his estates and about £ 100 from his professorship. Such
an income would have been considered opulence by Hooke, Flam¬
steed, and most of the scholars of the time. 15

12 Isaac Newton, ed. by Greenstreet, p. 15* , ,

13 Edleston, p. L. „ 14 C/. Chapter II, p. 47-

I 5 Brewster, (vol. I, p. 100) draws an absurdly pathetic picture of the ingratitude ot the
British nation towards men of science in general, and Newton in particular. In comparison
with the poets and other literary men, science has been liberally rewarded and Newton is

168

ISAAC NEWTON

The only authentic evidence of Newton’s financial worry rests on
the interpretation by Oldenburg of a letter in which he asked to have
his resignation presented to the Royal Society. The only reasons
given t lere for this request were that his scientific contributions were
not valued by the members and that he lived too far from London to
be able to attend the meetings. The only reference to money was that
he had forwarded his dues for half a year, which merely indicated
t at he was in arrears and had not previously been pressed for their
regular payment. Oldenburg, who was impetuous and tactless, at
once jumped to the conclusion that these specious excuses had been
given to conceal Newton’s embarrassment in not being able to pav
the annual dues of fifty-two shillings.

The Secretary of the Society had good cause to be interested in the
dues as it was a serious question during the early years of the Society,
ihe Treasurers reports were most discouraging and by 1674, only
ourteen years after the foundation, the arrears amounted to the
astonishing figure of £1957. The Record frequently called attention
to 111s embarrassing situation and many severe regulations were

X T . 1 ' 1 ... more prompt, but without much

success. Nothing better illustrates the little interest in science, and

the few workers, than the financial difficulties of the Society during
its early history. The Secretary was much distressed at the defection
of so promising a member, and further embarrassed Newton by rec-

TT, n , dlng ’ wlthout first obtaining his approval, that his dues
s ould be compensated for by giving discourses and demonstrations
to the Society. As a result of this recommendation the Council, at the
meeting of January 28, 1674/5, voted that: “Mr. Oldenburg having
mentioned, that Mr. Newton had intimated his being in such cir¬
cumstances, that he desired to be excused from the weekly payments

Lone shilling], it was agreed by the council, that he should be dis¬
pensed with, as several others were.”

When Newton received notice of this generous proposal, he was
placed in a most awkward position. He had not asked to have his
dues remitted and he could hardly tell the Council that his real
motive for resigning was caused by his belief in their personal op¬
position and their indifference to his work. He sharply declined to

certainly not an example of neglect. He was generously and freely sUDoorted he ,h. tt„-
man. honoured by the whole nation^ its most aSSuff ind beC3me a

CHEMISTRY AND MATHEMATICS

169

serve as lecturer and demonstrator; and he apparently withdrew his
resignation and ignored the subject of dues. Meanwhile to Collins,
with whom he was franker and less reserved than with anyone else,
he specifically stated that he had been treated rudely, and could not
expect an impartial hearing. Lest he might be blamed by others, he
hoped his friend at least would not think it strange that to avoid
such treatment he “declines that conversation which hath occasioned
what is past.” 16

Newton, this year, made one of his rare visits to London, staying
there from February 9 to March 19. He attended, for the first time,
a meeting of the Royal Society on February 18, as the record states
that he and James Hoare, Esq., were admitted and signed the Reg¬
ister on that day. He also attended the meetings on March 11 and 18
in order to be present when Flooke was expected to repeat his ex¬
periments with the prism to settle the objections of Fr. Linus. For
some unknown reason, however, he was disappointed as Hooke
failed to try the experiment, and instead read a paper of his own on
diffraction and interference of light. The test was delayed for more
than a year, and it was not until April 27, 1676, that the Society
could inform Fr. Linus and his colleagues at Liege that the experi¬
ment had been tried and had succeeded as Newton had all along as¬
serted it would. A trifling incident occurred at one of the meetings
which is typical of Newton’s thoughtfulness and amiability. When
he returned to Cambridge, he wrote to Oldenburg that he had met at
the Society an ancient Gentleman, who, being thick of hearing, had
enquired of him about Mr. Mace’s Otocousticon, or improved ear
trumpet. 17 Owing to a pressure of business he had neglected to at¬
tend to the request and was now enclosing a description of the instru¬
ment which he begged might be forwarded with his apology.

But, the trip to London had been undertaken for another and
much more important purpose. Either by the advice and backing of
his friends (amongst whom we should undoubtedly include the
Master of Trinity), or on his own initiative, a petition of indulgence
had been prepared for the Crown that he be permitted to retain his
fellowship without entering into orders so long as he held his profes¬
sorship. Edleston thought that the patent had been drawn up by

16 It should be remembered that the word, conversation, was not then limited to oral com¬
munication but was the common expression for all social intercourse. We can, I think, dis¬
miss the idea that Newton was at any period of his life in serious financial straits.

17 Conduitt states that Newton was much interested in making, and improving, ear trump¬
ets. Portsmouth Collection.

170

ISAAC NEWTON

Newton, himself, as a copy of it in his handwriting was found among
the Lucasian manuscripts. 18 Following the body of the text there is
the memorandum, also in Newton’s hand:

Whitehall, March 2, 1674 O. S.

His Majesty being willing to give all just encouragement to learned
men who are and shall be elected to the said Professorship, is gra¬
ciously pleased to refer this draught of a Patent unto Mr. Attorney
General to consider the same, and to report his opinion what his
Majesty may lawfully do in favour of the said Professors as to the
indulgence and dispensation proposed and desired. And then his
Majesty will declare his further pleasure. ^ Coventry

The draught was adopted: the actual instrument, (coinciding with
the draught except in two unimportant particulars), with the broad
seal attached, is in the Registry’s office (Box 21. G. 1.2) entitled:
A grant to the Mathematical Professor in Cambridge

Pigott. 19

This was a great, and unusual, distinction paid to Newton in rec¬
ognition of his high attainments. Just a few months previously,
Francis Aston had failed to obtain a similar dispensation on his own
account, although it was backed by the powerful interest of Sir
Joseph Williamson, Principal Secretary of State. This honour and
the favourable reception he had evidently received from the Royal
Society did much to restore his tranquillity of mind, and we hear
nothing further of his desire to resign.

Newton’s correspondence of the year was confined to some tech¬
nical notes on the solution of equations, and letters to Oldenburg
relative to his optical work. In one of these latter he mentioned an
experiment in electricity which immediately aroused the curiosity of
the Society. He supported a glass plate, four inches broad and a
quarter of an inch thick, on a wooden frame so that it should lie about
one-sixth of an inch from a table. Under the glass, he placed some
tiny, triangular bits of very thin paper, the wings of flies, etc. He

18 This hardly seems conclusive as Newton may well have made a copy of such a docu¬
ment even if it were drawn up by someone else.

19 A transcript of the patent is preserved in the College Archives, with the heading: “In-
dulgentia Regia Professori Mathematico concessa, dignissimo Viro M ro Isaaco Newton, hujus
Collegii Socio, istud munus tunc temporis obeunte.” This note gnd the full text of the pat*
ent is given in Edleston, p. xlix.

CHEMISTRY AND MATHEMATICS

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then rubbed the glass with a cloth to electrify it; whereupon, the
papers jumped to the glass and then back to the table, “the motion
of the papers would continue sometimes while I counted a hundred;
every paper leaping up about twenty times more or less, and down as
often.” The explanation of this electric hail, as it is sometimes called,
is that the papers are attracted to the electrically charged glass and,
having received a like charge from contact with it, they are then re¬
pelled. When they touch the table, this little charge leaves them and
the operation is repeated until the electricity has leaked from the
glass plate. To Newton, the experiment was important, as he thought
it was a confirmation of his belief that electricity might be a univer¬
sal force which caused cohesion, chemical affinity, and all other mo¬
lecular phenomena.

Such was the lack of experimental skill of the members of this most
learned society in comparison with Newton’s, that the simple experi¬
ment repeatedly failed when they tried to perform it, and several
letters 20 passed before the demonstrator, presumably Hooke, suc¬
ceeded in verifying it at the meeting on Jan. 13, 1675/6: “Mr. New¬
ton’s experiment of glass rubbed, to cause various motions in bits of
paper beneath, being made according to his more particular direc¬
tions, succeeded very well. The rubbing was made both with a
scrubbing brush, made of short hog’s bristles, with a knife, the haft
of the knife made of whalebone, and with the nail of one’s finger.
It appeared, that touching many parts at once with a hard and
rough body, produced the effect expected. It was ordered, that Mr.
Newton should have the thanks of the Society, for giving himself
the trouble of imparting to them such full directions for making the
experiment.

Newton, relieved from the worry of losing his fellowship and en¬
couraged by the attentions paid him by the Royal Society, decided to
tempt criticism again by offering a new discourse on colours. This
communication was the longest and most elaborate paper which he
submitted to the Society. He reviewed his past work, added an out¬
line of an hypothesis on the nature of light and on a luminiferous
aether, and described his most recent experiments on diffraction and
the colours produced in thin transparent plates by interference or,
as he called it, by fits of easy reflection and transmission. The dis¬
course was so long that its consideration occupied several sessions.
The ideas contained in it have been discussed at length in a previous

20 Horsley, vol. Ill, p. 375 et seq. 21 Birch, Hist. Roy. Soc., Ill, p. 271.

172

ISAAC NEWTON

chapter, but some personalities were indulged in which should be
touched upon.

He evidently felt that an hypothesis on the nature of light, com¬
ing from him after his categorical refusal to consider the speculations
of others as not being germane to science, needed a word of explana¬
tion and apology. His letter to Oldenburg, accompanying the paper,
is worth quoting as it seems to indicate that he wished to show that
his stand against hypothetical reasoning did not come from an in¬
ability to meet his opponents on their own ground. It shows also
how insidiously the desire for speculation steals into the mind when
once the doors have been opened to it.

Newton to Oldenburg

[1676]

Sir,—I have sent you the papers I mentioned, by John Stiles. Upon
reviewing them I find some things so obscure as might have deserved
a further explication by schemes [diagrams]; and some other things
I guess will not be new to you, though almost all was new to me
when I wrote them. But as they are, I hope you will accept of them,
though not worth the ample thanks you sent. I remember in some
discourse with Mr. Hooke, I happened to say that I thought light
was reflected, not by the parts of glass, water, air, or other sensible
bodies, but by the same confine or superficies of the ethereal medium
which refracts it, the rays finding some difficulty to get through it
in passing out of the denser into the rarer medium, and a greater
difficulty in passing out of the rarer into the denser; and so being
either refracted or reflected by that superficies, as the circumstances
they happened to be in at their incidence make them able or unable
to get through it. And for confirmation of this, I said further, that I
thought the reflection of light, at its tending out of glass into air,
would not be diminished or weakened by drawing away the air in
an air-pump, as it ought to be if they were the parts of air that re¬
flected ; and added, that I had not tried this experiment, but thought
he [Hooke] was not unacquainted with notions of this kind. To
which he replied, that the notion was new, and he would the first
opportunity try the experiment I propounded. But upon reviewing
the papers I sent you, I found it there set down for trial; which makes
me recollect that about the time I was writing these papers, I had
occasionally observed in an air-pump here at Christ’s College, that I
could not perceive the reflection of the inside of the glass diminished

CHEMISTRY AND MATHEMATICS

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in drawing out the air. This I thought fit to mention, lest my
former forgetfulness, through my having long laid aside my thoughts
on these things, should make me seem to have set down for certain
what I never tried.

Sir,—I had formerly purposed never to write any hypothesis of
light and colours, fearing it might be a means to engage me in vain
disputes; but I hope a declared resolution to answer nothing that
looks like a controversy, unless possibly at my own time upon some
by-occasion, may defend me from that fear. And therefore, consid¬
ering that such an hypothesis would much illustrate the papers I
promised to send you, and having a little time this last week to spare,

I have not scrupled to describe one, so far as I could on a sudden
recollect my thoughts about it; not concerning myself, whether it
should be thought probable or improbable, so it do but render the
paper I send you, and others sent formerly, more intelligible. You
may see by the scratching and interlining it was done in haste; and I
have not had time to get it transcribed, which makes me say I reserve
a liberty of adding to it, and desire that you would return these and
the other papers when you have done with them. I doubt there is
too much to be read at one time, but you will soon see how to order
that. At the end of the hypothesis you will see a paragraph, to be
inserted as is there directed. I should have added another or two, but
I had not time, and such as it is I hope you will accept it. Sir, I am

your obedient servant, j s Newton . 22

At the conclusion of the reading of the first portion of Newton’s
paper the Record stated: “After reading this discourse, Mr. Hooke
said, that the main of it was contained in his Micrographia, which
Mr. Newton had only carried farther in some particulars. 23 There is
some basis of truth in Hooke’s criticism. The fundamental ideas and
experiments of Newton, on both diffraction and colours in thin
plates, had undoubtedly been suggested by the work of Grimaldi
and Hooke, and he had been, to say the least, not generous in his
acknowledgement of his indebtedness to them. He had also modi¬
fied his early ideas of the nature of light and had incorporated, in
part, Huygens’s and Hooke’s conception of the role of ethereal
waves. A full statement of his indebtedness to others would probably
have gained Hooke’s support and would certainly have soothed his

22 Brewster, I, p. 133. Cf. supra, Chapter IV, p. 116. 23 Birch, III, p. 269.

I 74

ISAAC NEWTON

irritable vanity. Newton had so far surpassed the work of his prede¬
cessors that he could well have afforded to give them ample credit
for their work. Hooke’s criticism may have been made with a slur¬
ring tone; he may even have been offensive in manner; and Olden¬
burg, who had no love for him, dispatched an account to Newton
which lost nothing in the telling. Newton, stung to the quick, inter¬
polated in his paper, when it was published, a bitter attack on
Hooke’s own work and attitude towards himself. He accused him
of borrowing most of his own ideas from Descartes and others,
merely changing that philosopher’s pressing or progressive motion
of the medium into a vibrating one. Then he asserted, that Hooke’s
and his hypotheses had little in common; while his own two main
experiments, “without which the manner of the production of those
colours is not to be found out, were not only unknown to him
[Hooke] when he wrote his Micrography, but even last spring, as I
understood, in mentioning them to him.” His first assertion is open
to question, but his second is an indisputable fact, and is the factor
in Newton’s work which makes him stand out from his contempora¬
ries. He closed his vindication in these words: “He left me to find
out and make such experiments about it, as might inform me of the
manner of the production of those colours, to ground an hypothesis
on; he having given no further insight to it than this, that the colour
depended on some certain thickness of the plate; though what that
thickness was at every colour, he confesses in his Micrography, he
had attempted in vain to learn; and therefore, seeing I was left to
measure it myself, I suppose he will allow me to make use of what I
took the pains to find out. And this I hope may vindicate me from
what Mr. Hooke has been pleased to charge me with.” 24

We may judge that the discourse excited the admiration of the
Society but that many, at least, still favoured the opinions of their
Curator, Hooke. After the close of the reading of the paper, there
followed a formal debate on the question whether “the rays of light,
which, though alike incident in the same medium, yet exhibit dif¬
ferent colours, may not reasonably be said to owe that exhibition of
different colours to the several degrees of the velocity of pulses, rather
than, as Mr. Newton thought, to the several connate degrees of re-
frangibility of the rays themselves? Mr. Hooke was of opinion,
that the former of these ways was sufficient to give a good account
of the diversity of colours.” 25

24 Birch, III, p. 279.

25 Ibid., Ill, p. 295.

CHEMISTRY AND MATHEMATICS

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The controversy had reached an acute stage, and we can assume
that pressure was put on Hooke to appease the wounded feelings of
the younger man. At least he, although he had not been the one to
indulge in personalities, took the first step towards a conciliation by
sending the following letter:

Hoo\e to Newton

Robert Hooke—These to my much esteemed friend, Mr. Isaac
Newton, at his chamber in Trinity College in Cambridge.

S r ,—The hearing a letter of yours read last week in the meeting of
the Royal Society, made me suspect that you might have been some
way or other misinformed concerning me; and this suspicion was the
more prevalent with me, when I called to mind the experience I
have formerly had of the like sinister practices.*" 6 I have therefore
taken the freedom, which I hope I may be allowed in philosophical
matters to acquaint you of myself. First, that I do no ways approve
of contention, or feuding or proving in print, and shall be very un¬
willingly drawn to such kind of war. Next, that I have a mind very
desirous of, and very ready to embrace any truth that shall be dis¬
covered, though it may much thwart or contradict any opinions or
notions I have formerly embraced as such. Thirdly, that I do justly
value your excellent disquisitions, and am extremely well pleased to
see those notions promoted and improved which I long since began,
but had not time to complete. That I judge you have gone farther
in that affair much than I did, and that as I judge you cannot meet
with any subject more worthy your contemplation, so I believe the
subject cannot meet with a fitter and more able person to enquire
into it than yourself, who are every way accomplished to complete,
rectify, and reform what were the sentiments of my younger studies,
which I designed to have done somewhat at myself, if my other
more troublesome employments would have permitted, though I
am sufficiently sensible it would have been with abilities much in¬
ferior to yours. Your design and mine are, I suppose, both at the
same thing, which is the discovery of truth, and I suppose we can
both endure to hear objections, so as they come not in a manner of
open hostility, and have minds equally inclined to yield to the
plainest deductions of reason from experiment. If, therefore, you
will please to correspond about such matters by private letters, I
shall very gladly embrace it; and when I shall have the happiness

20 These references are, of course, to Oldenburg.

176

ISAAC NEWTON

to peruse your excellent discourse, (which I can as yet understand
nothing more of by hearing it cursorily read,) I shall, if it be not
ungrateful to you, send you freely my objections, if I have any, or
my concurrences, if I am convinced, which is the more likely. This
way of contending, I believe, to be the more philosophical of the
two, for though I confess the collision of two hard-to-yield contend¬
ers may produce light, [yet] if they be put together by the ears by
other’s hands and incentives, it will [produce rathjer ill concomi¬
tant heat, which served for no other use but . . . kindle—coal. S r ,
I hope you will pardon this plainness of, your very effectionate

humble serv* _ TT 27

Robert Hooke.

1 675 / 6 -

Newton to Hoo\e

Cambridge, February 5, 1675/6.

D r Sir,—At the reading of your letter I was exceedingly pleased
and satisfied with your generous freedom, and think you have done
what becomes a true philosophical spirit. There is nothing which
I desire to avoid in matters of philosophy more than contention, nor
any kind of contention more than one in print; and, therefore, I
most gladly embrace your proposal of a private correspondence.
What’s done before many witnesses is seldom without some further
concerns than that for truth; but what passes between friends in
private, usually deserves the name of consultation rather than con¬
tention; and so I hope it will prove between you and me. Your
animadversions will therefore be welcome to me, for though I was
formerly tired of this subject by the frequent interruptions it caused
to me, and have not yet, nor I believe ever shall recover so much
love for it as to delight in spending time about it; yet to have at once
in short the strongest objections that may be made, I would really
desire, and know no man better able to furnish me with them than
yourself. In this you will oblige me, and if there be any thing else in
my papers in which you apprehend I have assumed too [. . .] if
you please to reserve your sentiments of it for a private letter, I hope
you [will find that I] am not so much in love with philosophical
productions, but that can make them yield. . . . But, in the mean
time, you defer too much to my ability in searching into this subject.
What Descartes did was a good step. You have added much several
ways, and especially in considering the colours of thin plates. If l

27 Portsmouth Collection.

CHEMISTRY AND MATHEMATICS

177

have seen farther, it is by standing on the shoulders of giants . But
I make no question you have divers very considerable experiments
beside those you have published, and some, it’s very probable, the
same with some of those in my late papers. Two at least there are,
which I know you have often observed,—the dilatation of the col¬
oured rings by the obliquation of the eye, and the apparition of a
black spot at the contact of two convex glasses, and at the top of
a water-bubble; and it’s probable there may be more, besides others
which I have not made, so that I have reason to defer as much or
more in this respect to you, as you would to me. But not to insist
on this, your letter gives me occasion to enquire regarding an ob¬
servation you was [sic] propounding to me to make here of the
transit of a star near the zenith. I came out of London some days
sooner than I told you of, it falling out so that I was to meet a friend
then at Newmarket, and so missed of your intended directions; yet
I called at your lodgings a day [or] two before I came away, but
missed of you. If, therefore, you continue ... to have it observed,
you may, by sending your directions, command . . . your humble

servant > Is. Newton. 29

These two letters have all the earmarks of an attempt towards a
formal reconciliation which had been urged by others, and recog¬
nised as proper by themselves. Each of the writers expresses great
admiration for the other’s ability; each deprecates the public and
partisan discussion of their opinions; and each requests the other to
criticise rigorously his work, but to do it privately.

Two such men may indulge in general sentiments of a high and
abstract order, and use elaborate expressions of personal esteem; but
there could not be found two men, who were so temperamentally
incapable to form a lasting friendship. Both were suspicious and
sensitively vain. In Hooke, these qualities showed themselves by
wrathful explosions and by reiterated accusations that he had been

28 This celebrated saying is usually quoted as being original with Newton, but it really
goes back much earlier. Burton, in his Anatomy of Melancholy, quotes Didacus Stella, In
Luc. 10. tom. 2, as saying, “Pigmei Gigantum humeris impositi plusquam ipsi Gigantes
vident.” The idea, that pygmies can see farther than giants merely by being elevated on their
shoulders, is a specious one. We should remember that, however high a pygmy may be raised,
he will still interpret what he sees with the mind of a pygmy. Newton saw farther and he
understood better because he was Newton. Perhaps, even, our complacent idea that wc sec
farther, and thus better than the giants of earlier times may also be specious,—unless there
be a modern Newton. Italics mine.

29 Portsmouth Collection.

178

ISAAC NEWTON

robbed of the fruits of his work; in Newton when opposed, they
were equally apparent in a cold assumption of a disdain for fame
and a silent retirement into his ivory tower. It is needless to say that
their correspondence was limited to official communications; the
embers of hostility still existed and needed only a new occasion to
make them blaze up in public. They never forgave each other;
Hooke continued to claim that he had anticipated Newton’s work,
and Newton maintained his aloof attitude towards the Society till
Hooke’s death relieved him from the fear of his insinuations.

It is not necessary to dwell on Hooke’s letter but there is a need
for criticising Newton’s as it impresses me differently from the com¬
mon opinion. 30 The point in question is his striking illustration of
having seen farther because he stood on the shoulders of giants. This
sentence is universally quoted as a generous tribute to the genius of
others, and an extraordinary example of his own modesty. I confess
that I cannot agree with such an opinion. We should bear in mind
that this was the expression of a young man who was known to the
world for having done one piece of work excellent in itself, but one
whose far reaching effects could not then have been foreseen. If it
had been made towards the close of his life when the world recog¬
nised him as having seen farther than the giants of intellect, and
when he had fulfilled to his own satisfaction the promise of his
youth; then I might agree that it could be termed modest, although
I should rather deem it a cold and exact statement of fact.

Consider also how little credit, and in how slighting a manner,
Newton concedes to the giants, on whose shoulders he was standing.
To Descartes, whom he persistently ignored or slighted, he admits
only that he had taken “a good step” and Hooke, who had enriched
the whole field of science, he compliments only to the extent of

30 Brewster, and his opinion as the standard biographer of Newton has been unquestion¬
ably accepted, comments: “These beautiful letters, emulous of good feeling and lofty prin¬
ciple, throw some light on the character and position of two of the greatest of our Eng¬
lish philosophers.” He lays entirely too much blame on poor Oldenburg, who may have in¬
creased, but who did not cause the enmity. His only criticism of Newton is the mild state¬
ment “that he did not do justice to the valuable communication of this rival.” The fact is,
that Newton had given him no credit, and had persistently either ignored or condemned his
work. Brewster, however, dealing with Hooke, lamely says that he cannot give his sanction
to so harsh a judgement as that pronounced by a distinguished philosopher who “ventured to
describe him as a ‘bad man’ but “that influenced by the charity which thinketh no evil,
we may find in the physical constitution and social position of Hooke, and to a certain extent
in the injustice of his enemies, some apology for that jealousy and quickness of temper which
may have been more deeply regretted by himself than it was felt by others.” Certainly the
faults of character of the two men are very differently treated, and Brewster is a flagrant
example of those whom he accuses of having tried to add ‘ to the intellectual fame of Newton
by the moral depreciation of his rival.” Cf. Brewster, vol. I, pp. 143-145.

CHEMISTRY AND MATHEMATICS

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having “added much in several ways,” and especially in one limited
field. It should be remembered that in addition to those two, the
other giants were Copernicus, Kepler, Galileo, and Huygens; was it
modest, or calculated to promote peace, to say that he then saw
farther than they? Those who have approved Newton’s modesty
so unreservedly may have forgot that their judgement is one of ret¬
rospect, and might have been different if they, like Hooke, had read
the letter when it was written. It should be borne in mind that I
am not seriously criticising Newton’s use of the phrase. In my opin¬
ion it was but a more or less stereotyped reply to Hooke s formal
compliment to him. Just as the signature of “your humble and
obedient servant” was a social custom of the day and not meant to
be taken literally, so also the mutual depreciation of their work was
merely a form of politeness. The need for discussion arises from the
fact that Brewster, following the example of Newton’s contempo¬
raries, cites the phrase as a proof of his extreme modesty, and it is
frequently quoted in the same spirit today as a rebuke to the pre¬
tensions of mediocrity. Newton was piously humble in the presence
of God; but he had no illusions of what would have been false
modesty when he compared his work with that of other men.

Two minor incidents of this year may be noted. On December
1st, he gave a copy of St. Irenaeus, just published in Paris, to the
College Library. This is the first instance of a donation of a book to
his College; the giving of books to the College, and to the Royal
Society, became a frequent occurrence. And Mercator stated in his
new Astronomical Institutions that the celebrated Isaac Newton had
explained to him most elegantly the cause of the moon’s libration.
Newton had discovered in 1673 that, if the rotation of the moon on
its axis corresponded exactly with the period of its revolution about
the earth, then we could see only the same hemisphere of its surface;
but, owing to irregularities in its orbital motion, we can observe
somewhat more than half the surface.

The year, 1676, was an important and busy time in Newton’s life.
He carried on a long correspondence with Oldenburg and the Royal
Society in connection with his electrical experiment which has been
described. His long hypothesis on the nature of light and the aether
was read to the Society,—the last paper he communicated to it on
that branch of science. The discussion with Hooke had ended with
a temporary truce, but the personalities indulged in had left a feel¬
ing of bitterness with both; and the controversy with Linus and his

i8o

ISAAC NEWTON

colleagues had also drifted into a disagreeable phase. One of them,
Gascoines, had accused him of deceit by sending private directions
which differed from the printed accounts of his experiments; and
this charge Newton indignantly and truthfully denied. He had also
insinuated that both Newton and Oldenburg had maliciously tried
to involve him in an unpleasant controversy. To meet this charge,
he wrote to Oldenburg: “This is the history of Mr. Linus’s business,
so far as I know it; which I have set down that his friends may see
he has not been dealt with obliquely, as they seem to apprehend.
All that I think they can object to you is, that you were at a stand,
because you could not engage me in the controversy, and to me, that
I had no mind to be engaged: a liberty every body has a right to,
and may gladly make use of, sometimes at least, and especially if he
want leisure, or meet with prejudice or groundless insinuations. But
I hope to find none of this in Mr. Gascoines. The handsome genius
of his present letter makes me hope it for the future. In the mean
time I desire, with him, that you would publish Mr. Linus’s letters
as soon as you can conveniently, to prevent further misapprehen¬
sions.” 31

In spite of the fact that Newton was displeased with the attitude
of some of the members of the Royal Society and absented himself
from the meetings, he maintained a theoretical interest in its welfare
and, at some period of his life, drew up a memorandum for improv¬
ing and enlarging its usefulness. The scheme was found by Brew¬
ster amongst the Portsmouth Papers and was never published. His
main idea was to appoint a small number of Fellows, perhaps three
or four, in each of the principal branches of science, who should
devote themselves to the advancement of their specialties. They
would be obliged by pensions, or forfeits, to attend the meetings,
report on books and experiments of others, and demonstrate new
inventions and experiments of their own. It is quite evident that
Newton had been influenced by Bacon and was advocating a closer
adherence to his scheme for enlisting a concerted scientific army,
divided into companies and led by captains for each science. The
plan has never been adopted and, as the Society increased in age
and in importance, the honour of being elected a member, and of
presenting papers, has become so great, that there is no lack of volun¬
tary contributions.

Newton’s mind was groping for a general explanation of the

31 Macclesfield, II, p„ 387.

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cause of phenomena, and he was evidently turning to the conception
of a mechanistic universe in which a universal aethereal substance
would, by its actions, account for all phenomena, both organic and
inorganic. Since he later amplified and perfected his first outline of
a cosmical hypothesis, it will be sufficient here to give only its main
features. According to his ideas, the nature of this medium is as¬
sumed to be similar in “constitution with air, but far rarer, subtiler,
and more elastic.” It is not to be supposed, however, that this me¬
dium is one uniform matter, since it is composed partly of the main
phlegmatic body of aether, and partly of other various aethereal
spirits, much after the manner that air is compounded of the phleg¬
matic body of air intermixed with various vapours and exhalations.
“For the electric and magnetic effluvia, and the gravitating principle,
seem to argue such variety.... Nature is a perpetual circulatory work¬
er, generating fluids out of solids, and solids out of fluids, fixed things
out of volatile, and volatile out of fixed, subtile out of gross, and gross
out of subtile, some things to ascend and make the upper terrestrial
juices, rivers, and the atmosphere, and by consequence others to
descend for a requital to the former, and as the earth, so perhaps
may the sun imbibe this spirit copiously, to conserve his shining, and
keep the planets from receding further from him.” Not only do the
protean changes of this medium produce all the phenomena we
perceive in the physical world, but this aether also composes the
animal spirits which he says are “of an aethereal nature, subtile
enough to pervade the animal juices as freely as the electric, and
perhaps magnetic, effluvia do glass. . . . Thus may therefore the
soul, by determining [driving] this aethereal animal spirit or wind
into this or that nerve, perhaps with as much ease as air is moved
in open spaces, cause all the motions we see in animals. . . . And
what is said of muscular motion may be applied to the motion of
the heart, only with this difference; that the spirit is not sent thither
as into other muscles, but is continually generated there by the
fermentation of the juices with which its flesh is replenished and as
it is generated, let out by starts into the brain, through some con¬
venient ductus to perform those motions in other muscles by in¬
spiration, which it did in the heart by generation.” 32

In an explanatory letter to Oldenburg, which accompanied this
scheme and was not to be published, he added his idea of God, as

32 Brewster I, p. 390 et seq .—Printed in full from the paper which Newton submitted to
the Royal Society on December 9, 1675.

182

ISAAC NEWTON

creator and governor of this mechanistic universe; who first created
the fermental aether and its principles of action, and then assigned
to a lesser power, Nature, the duty of forming and operating the
perceptible mechanical universe. This idea bears a close resemblance
to the Platonic hypothesis of dual real and imaginary worlds as
decribed in the Timaeus; and it leads one to suspect the influence
of Henry More and the Cambridge Platonists. His conception of
Nature, as “a perpetual circulatory worker,” is the Renaissance echo
of the universal flux of Heraclitus as interpreted by the Stoics.

“Where I say that the frame of nature may be nothing but aether
condensed by a fermental principle, instead of those words write,
that it may be nothing but various contextures of some certain
aethereal spirits, or vapours, condensed as it were by precipitation,
much after the manner that vapours are condensed into water, or
exhalations into grosser substances, though not so easily condensible;
and after condensation wrought into various forms, at first by the
immediate hand of the Creator, and ever since by the power of
Nature, who by virtue of the command, ‘Increase and multiply,’
became a complete imitator of the copies set her by the Protoplast.
Thus perhaps may all things be originated from aether, etc.” 33

For one who reproached his critics with the rebuke that hypothesis
was not science, Newton could match the best of them in unbridled
speculation, when he gave free rein to his imagination; but, in
justice to him it should be added, that he rarely confused such
speculations with science.

The personal incidents of Newton’s life are so meagre that a
biographer should be pardoned if he makes too much of a rather
trifling matter about the planting of apple trees and the making of
cider. At least it shows that he was, as a country gentleman, keen
about agriculture. He enquired of Oldenburg for information about
the best kind of apple trees for cider which could be obtained from
a Mr. Austin, an Oxonian planter. The growers about Cambridge
made good profit from cherry trees but had not succeeded with
apples for cider. The difficulty was “that Red Streaks” [the famous
fruit for cider in other parts] did not maintain their reputation in
that country. “The tree,” he wrote, “thrives well here, and bears as
much fruit, and as good to look as in other countries; but the cider
made of it they find harsh and churlish” and also the cider will
not keep above a year whereas that made of “Red Streaks” in other

33 Macclesfield, II, p. 389.

CHEMISTRY AND MATHEMATICS

183

places will keep three years or more. So he enquired whether he
could obtain grafts, rather than sprags, from Mr. Austin for im¬
proving their trees. His letters show an intimate knowledge of the
subject. It would be interesting to know whether the cider of Cam¬
bridge is, at present, improved, and, if so, whether the improvement
is due to Newton’s efforts.

During this year, Newton’s correspondence with Collins was lim¬
ited to one or two letters, and the only news of a general nature is
his denial of a rumour that he was finally about to publish a book
on mathematical series. He supposed the rumour had its origin
from the fact that his edition of Kinkhuysen’s Algebra had been
declined by the University Press on account of other work on hand,
but was now in the hands of a Cambridge book-seller who had
undertaken to get it printed. It should be a satisfaction to writers
of rejected manuscripts to learn that a work by Newton was de¬
clined by the University Press because of other work on hand. He
also advised James Gregory to publish his work on infinite series,
and not to wait for the appearance of anything of his own: he adds
that Gregory’s improvement of the method of infinite series does
not interfere with his ideas and is, also, of a limited usefulness. He,
therefore, approved the publication lest the public should be hin¬
dered from “enjoying a thing so valuable.” 34

This same year is also memorable in the history of science as the
time when the seeds of the great controversy on the invention of
the calculus were sown between Newton and Leibniz. This un¬
fortunate dispute smouldered for a third of a century before it burst
into a blaze of recrimination which smirched the reputation of the
two greatest philosophers of the age. Even at the risk of some
repetition this controversy must be touched upon currently, although
a detailed discussion of its tangled history will be given in a later
chapter.

Previous to the Renaissance, mathematicians had followed the
Greek method of regarding a curved line as a series of points placed
as closely together as one wished. Thus, a curve was to them a series
of geometric points connected together by imaginary straight lines.
In consequence of this static idea the length of a circle, or other
curved line, was merely the limit between the lengths of two in¬
scribed and circumscribed polygons of an indefinitely large number
of sides. Beginning with the Renaissance, interest had shifted from

34 Macclesfield, II, p. 397.

184

ISAAC NEWTON

problems relating to such static lines to an enquiry of how they had
been made; that is, to regarding them as the truly curved paths of
a continuously moving small body. The chief creator of this new
field of dynamics was Galileo, whose principal work lay in deter¬
mining the laws of motion of bodies, and the nature and measure of
force. The problem of geometry had thus been changed from a
consideration of straight lines to the necessity of finding an expres¬
sion for the lengths and properties of continuously curved paths of
motion. If one desires to study the path of a stone whirled on the
end of a string it is easy to see that there is then no question of
rectilinear jumps from position to position, but a steadily flowing
motion. One of the important results of Galileo’s dynamical dis¬
coveries was the invention of the analytical geometry by Descartes.
The purpose of this geometry was to express the paths of moving
bodies in terms of algebraic equations, and it developed into an
efficient aid in solving these new problems in mechanics. The ad¬
vance of mathematics during the seventeenth century was extraor¬
dinarily rapid and, especially, in those branches which were con¬
cerned with the problems involved in the sciences of astronomy and
mechanics. It will be sufficient to point out that it was quickly rec¬
ognised that such problems of moving bodies were associated with
the expansion of functions in infinite series. In England, Wallis had
advanced so far in this analysis that he had reached the threshold of
the discovery of the infinitesimal calculus.

When considering Newton’s early mathematical work, we should
bear in mind that he studied chiefly the work of Descartes, Wallis,
and his master, Barrow. He, himself, acknowledged that he had been
led to his first discoveries in analysis and fluxions by Wallis’s Arith-
metica Infinitorum. It is now thoroughly established that during
his undergraduate days, and especially during his period of leisure
at Woolsthorpe because of the plague, he had extended Wallis’s
work on the expansion of quantities into infinite series, had found
expressions of a general nature for the lengths and tangents of
curves, and had evolved a method for calculating the areas subtended
by curved lines. Extraordinary as were these extensions to Wallis’s
work by a youth in his twenties, Newton had far surpassed them by
his capital discovery of what he termed Fluxions. The basis of this
discovery lay in his clearly recognised idea that the path of a moving
body should be regarded, not as a series of points, but as the graph
made by a continuously moving point. Since the velocity of a point

i8 5

CHEMISTRY AND MATHEMATICS

moving in a direction x is the distance traversed, divided by the
time, or x/t, we can express the same velocity by constantly reducing
the length, x, if we at the same time reduce, t, proportionately; thus,
a continuous and finite motion is equal to the quotient of an infini-
tesimal distance and an infinitesimal time. To the moving point, he
gave the name of a fluent, and for the velocity, he used the term,
fluxion, which he sometimes indicated by the symbol x, and some¬
times by the letter o placed before it. For changes in velocity, or ac¬
celeration, he at times used the symbol x.

Professor Child 38 who has made a very careful study of the se¬
quence of Newton’s mathematical ideas is of the opinion that in
1669, when his tract De Analyst was sent by Barrow to Collins and
by him to other scholars, “wonderful as is the work that has been ac¬
complished, yet the methods employed are merely a correlation of
what he has learned from Descartes, Wallis and Barrow, combined with
his original methods of infinite series and their reversion. In the true
sense of the word, he could not differentiate or integrate, except, as
we say nowadays, by first principles.’ He places the discovery o
the fluxions or calculus seven years later, on the ground that the
De Analyst contained all Newton knew at the time and does not
present the Binomial Theorem in its generalised form, without
which the development of a differential caculus, in any real sense, is
impossible. Now, the first authentic statement of this Theorem
occurs in a letter to Oldenburg, dated June 13, 1676. That this state¬
ment fixes the date of the discovery of the Binomial Theorem is sup¬
ported by another letter to Oldenburg written just four months later,
in which occurs the following passage italicised by me: “This is my
first entry into these meditations; and truly I should have forgotten
it, but that, some weeks ago, I once more referred to certain notes.

85 I found in the Portsmouth Collection, Sect. I, 5 XI, No. 3 o, the draught of a letter which
has never been published. As it gives an important, and new light, on the sources from
which Newton derived the fluxions I shall give an extract from it at this time. The docu¬
ment is most carefully written with many erasures and variants: I had the hint of this
method from Fermat's way of drawing tangents and by applying it to abstract equations,
directly and invertedly, I made it general. Mr. Gregory and Dr. Barrow used and improved
the same method in drawing of tangents. A paper of mine gave occasion to Dr. Barrow
r who PI showed me his method of tangents before he inserted it into this toth Geometrical
Lecture For I am that friend which he then mentioned.” As I stated in a previous chapter,
Laplace and Lagrange both give the credit to Fermat as the inventor of the calculus. But this
is the first time that direct evidence has been given of Newton s indebtedness to Fermat.

36 Greenstreet, p. H 7 > et ^eq. . , _ . , . , . .

37 The generalised form of the Binomial Theorem gives the expansion of a binomial

(x _j_ y) a into the infinite series, x n + nx 1> Y + (D!) y 2 + etc -> where n is any

integer or fraction.

i86

ISAAC NEWTON

. . . And thus became known to me, a general reduction of radicals
to infinite series, by the rule which I placed at the beginning of the
former letter, before that I had found the extraction of roots! > Pro¬
fessor Child s opinion carries the more weight since these two letters
were written to be forwarded to Leibniz, who had enquired about
Newton’s new method as he himself was interested in the same sub¬
ject. As we shall see later, Newton was, in these letters, describing
the sequence of his work accurately and, at the same time, protecting
his rights of discovery for fear that Leibniz would anticipate the
same method. The date of the discovery of the complete Binomial
Theorem seems settled without doubt as 16765 there remains only
the question whether a real differential calculus could be evolved
without the aid of that Theorem, a question which must be decided
by mathematicians.

The relations between Newton and Leibniz, which ended so
shamefully, began pleasantly enough with mutual esteem. They
were both young men, nearly of the same age, and on the threshold
of those remarkable careers which bulked so large in the history of
the thought of the seventeenth century. Leibniz had entered the
service of the Elector of Mainz and, in 1672, was summoned to Paris
by Louis XIV to explain a plan for an invasion and conquest of
drawn up by him, it is said, to distract Louis from a threat¬
ened attack on Germany. He had early been interested in mathe¬
matics and while he was in Paris he cultivated the friendship of its
learned society and, especially, of Huygens, who directed his atten¬
tion to mathematics and taught him the new Cartesian analysis. The
year before, he had sent a short tract, entitled Theoria Motus Ab¬
stract!, to the Paris Academy of Sciences which Dr. Hales thought
contained no obscure seeds of his differential calculus.”

In 1673, Leibniz travelled to London 38 in the train of the Duke
of Hanover and there he met the distinguished men of science, Boyle,

It will be of interest to give the intercourse of Leibniz with the Royal Society from the
actual records of the year, 1673. “At this meeting (January 22) was present Mons. Leibniz,
the author of the printed discourse, intitled, Hypothesis Physica Nova, dedicated by him in
1 -V u° f • ,£ lety - He now shewed them a new arithmetical instrument, contrived as he
said, by himself, to perform mechanically all the operations of arithmetic with certainty and
expedition.—He gave some proof of what he said, but acknowledged the instrument to be
imperfect, which he promised to get perfected, as soon as he should be returned to Paris
where he had appointed a workman for it.” ’

On February fifth, the irrepressible Hooke mentioned, “that he intended to have an
arithmetical engine made, which should perform all the operations of arithmetic with meat
expedition and certainty, without making use of the rhabdology [computation by means of

CHEMISTRY AND MATHEMATICS

187

Pell, Oldenburg, and others, and eagerly enquired into the new
matters occupying their attention. He was admitted to the Royal
Society, and presented for their criticism an intricate calculating
machine which he had invented. He stayed in London but a brief
time and returned to Germany where he was shortly afterwards ap¬
pointed librarian at Hanover. He maintained, however, his interest
in English scholarly work, and corresponded frequently with Olden-
burg.

In order to prepare the reader to follow the tangled story of the
early relations between Leibniz and Newton, a brief summary of
Newton’s mathematical work prior to the year, 1673, is now given.

Newton’s attention was first directed to the study of infinite series
in 1663, the year he graduated, by reading Wallis’s Arithmetica In -
finitorum and Barrow’s lectures. The year following, he derived a
method of determining lengths of curves, tangents, and the area of
circular sectors by the use of these series; and in 1669 he calculated
the area of an hyperbola.

He also discovered, in the same period, the essentials of the Bino¬
mial Theorem, which, besides its general importance, ultimately
provided him with the apparatus for inventing his fluxions; al¬
though Professor Child believes he did not develop the theorem to
its complete statement until 1676.

In 1665 and 1666, during his retirement to Woolsthorpe on account
of the pest, he made his great discovery of fluxions and wrote several
short papers which he laid away because he thought that others
would certainly discover the same method before he would be old

small rods, called Napier’s bones] and that much more simply than that of Mons. Leibniz.”
A month later, he produced his arithmetic engine and showed the manner of its operation.
He was asked to explain how it differed from Mons. Leibniz’s. In answer to this request, he
read a discourse on May seventh discussing such engines in general and remarked caustically:
‘‘As for the arithmetical instrument [of Leibniz] it seemed to me so complicated with wheels,
pinnions, cantrights, springs, screws, stops, and truckles, that I could not perceive it ever
to be of any great use, especially common use.—The design, indeed, is very good, which is
the only thing I was able to understand of it.—But I have an instrument now making, which
will perform the same effects with the German, which will not have a tenth part of the
number of parts, and not take up a twentieth part of the room.” I doubt whether either in¬
strument was ever made, although I have not discoverd notices of their further history..

At the meeting of February 19, “Mr. Oldenburg produced and read a letter in Latin, left
with him by Mons. Leibniz, dated at London, Pgth February, 167!, containing his desire
of being received into the Society.—This gentleman having been lately present at several
meetings of the Society, and at one of them having produced and shewed an ingenious
arithmetical engine, and in other respects given testimony of his abilities, and of his great
esteem for the Society, Sir Robert Moray having taken public notice hereof proposed him as
candidate.—April 9. Mr. Edward Barnard and Mons. Leibniz were unanimously elected into
the Society.—June 11. Mr. Oldenburg read a Latin letter to the Society from Mons. Leibniz,
dated at Paris, 1st June, 1673, giving them thanks for his election into their body.” Birch,
vol. Ill, pp. 76, 82, 92.

i88

ISAAC NEWTON

enough to write for the public. In these papers he sometimes used
dots above the letters to indicate a fluxion, but more often a small
letter in place of a capital. He, apparently, did not attach much
importance to specific notation; a serious error since appropriate
symbols are as important in mathematics as an alphabet and written
words are to a language.

His De Anaiysi per Aequationes was sent by Barrow to Collins
in 1669. This work contained probably all he knew about series up
to that time. There is much difference of opinion as to whether
this work contained anything on fluxions or the calculus. Newton’s
partisans hold that it did, and that an able mathematician could
have worked out his secret from it. Brewster, who was sufficiently
biased, is doubtful, but such critics as De Morgan, Professor Child,
and the continental mathematicians, hold that it did not. No part
of it was published until 1693 when Wallis, “having learned that
Newton’s Method of Fluxions passed in Europe as Leibniz’s Dif¬
ferential Calculus,” inserted a notice of Newton’s claim to the
method in the preface of the first volume, and some extracts in the
second volume of his Works. Collins had, however, made the
existence of the work known, and had intimated that an important
discovery had been made. The curiosity about the secret was wide¬
spread as he had written of it to James Gregory in Scotland; Bertet
and Vernon in Paris; Slusius in Holland; Borelli in Italy; Strode,
Oldenburg, Dary, and others, in England. It has been established
that Leibniz was acquainted with the work, and extracts from it
have been found in his note-books.

At this point, Leibniz enters the scene. His visit in London had
established an intimacy with the leading scholars of the country, and
he maintained an active correspondence with Oldenburg to keep in
touch with them. During the year 1673, we have preserved for us
two letters of his, dated at London, and four written from Paris.
These letters treat of mathematical subjects and describe freely and
fully his discoveries in the properties of numbers. The following
year, in two letters, he indicated clearly that he was becoming in¬
terested in the problem of determining the lengths and areas of
curved lines by the method of infinite series as developed by Wallis.
In an answer to these letters, Oldenburg hinted at the extensions
and improvements which James Gregory 39 and Newton were then

39 James Gregory (1638-1675), born in Aberdeen, became professor of mathematics at
St. Andrews, and later at Edinburgh. His reputation rests on his discovery of the reflecting

CHEMISTRY AND MATHEMATICS

189

busied with. Leibniz became keenly interested and asked for further
information. In reply, Oldenburg forwarded a communication, of
date December 10, 1672, from Collins describing the results which
Gregory and Newton had sent him in 1671. 40 Leibniz answered that
he was distracted by other business, and could not compare the
results with a certain method of great power upon which he had hit.
In the meanwhile, Oldenburg and Collins had been urging Newton
to disclose his astonishing discoveries, and especially his fluxions, as
it was evident that his rival was rapidly advancing along the same
lines and might eventually supplant him in the honour of the dis¬
covery.

Newton, overborne by these entreaties, wrote his epistola prior to
Oldenburg, dated 13 June, 1676, and requested him to forward it to
Leibniz. This he did, and enclosed in it extracts from Gregory’s
work. In the letter, while Newton explained his new method of
series and included a number of important examples, he did not
make any reference to his secret discovery of fluxions. He did, how¬
ever, give a vague hint that he had a more important method in his
mind: “From these examples, it may be seen how far the limits
of analysis are extended by infinite series of this sort: in fact their
aid may be employed for almost all problems excepting some nu¬
merical ones similar to those of Diophantus. But, it still lacks being
a universal method without some further method of extending in¬
finite series.—How this may be done, there is not now time to ex¬
plain (jam non vacat dicere).”

Such an evasion naturally whetted Leibniz’s curiosity the more
keenly, and he sent an answer to Oldenburg for Newton, on 27
August, 1676, asking for further information and adding a theorem
for transmuting figures into one another. This theorem made it
evident that he had travelled far towards the discovery of the cal¬
culus. He must have guessed that his and Newton’s methods were

telescope and on his work in the new geometry. He was an admirer and friend of Newton.
His nephew, David Gregory (1661-1708), was also a distinguished mathematician. He was
first appointed professor at Edinburgh and afterwards Savilian professor of astronomy at Ox¬
ford, largely on the recommendation of Newton. He was one of the heartiest admirers and
friends of Newton, and supported his new gravitational mechanics.

40 This letter figured largely in the final phase of the controversy. It was used as one of
the principal documents against Leibniz by the investigating Committee of the Royal Society.
It is now generally agreed that the letter could not have given a clue to the invention of the
calculus. But the discussion on the point is academic as it has been proved by De Morgan
that Oldenburg sent only a review of the letter to Leibniz and omitted the illustrative ex¬
ample on which the charge of plagiarism rested. For proof of this statement, cf. De Mor¬
gan, Essays, p. 69, and also infra, Chapter XV.

190

ISAAC NEWTON

probably similar in principle and would hope that he might have a
frank reply. It succeeded so far as to arouse Newton to write a long
and elaborate letter to Oldenburg on 24 October, 1676, to be for¬
warded.

This celebrated epistola posterior gave in detail the history of
Newton’s first discovery of the method of series and its later devel¬
opments. In it also, he enlarged on his tract De Analyst and gave the
solution of several problems; and then, having reached the point
when an explanation of his method of fluxions, or calculus, would
logically follow, he abruptly broke off with the statement, “the basis
of these operations, sufficiently obvious (since now I cannot continue
my explanation) I have thus rather concealed 6a 2c d x 13c 2f
yi 3I 9n 40 4q 2r 4s 9t 12V x.” 41 After the solution of certain
problems by series he, at the end of the letter wrote: “But yet, lest I
seem to have said too much, the inverse [integration] problem of
tangents is more difficult to expand in powers than the others. For
solving them I use a double method; the one more elegant, the other
more general. It seems best to write down both, at present, in tran¬
scribed letters, lest if others should discover the same, I should be
compelled to change the method into another. 5a 2c d x ioe 2f h i2i
4I 3m ion 60 2q r 7s nt iou 3X: 11a b 3c 2d ioe x g ioi
2I 4m 7n 60 3p 3q 6r 5s nt 7U x, 3a c x 4c g h 6i 4I 4m
5 n 80 q 4r 3s 6t 4U, 2a 2d x 5e 3i 2m 2n 20 p 3r 5s 2t 2u.” 42

On the same day he wrote the following letter which lacks an
address.

Newton to [Collins or Oldenburg?]

October 24, 1676.

To M. Leibniz’s ingenious letter I have returned an answer, which
I doubt is too tedious. I could wish I had left out some things, since
to avoid greater tediousness I left out something else, on which they
may have some dependence. But I had rather you should have it

41 The sentence published later by Wallis from this jumble of letters was “Data ^Tquatione
quotcumque, fluentes quantitates involvente, fluxiones invenire, et vice versa,”—given any
equation, involving fluent quantities, to find the fluxions, and vice versa.

42 The sentence to be derived is, as given by Wallis: Una Methodus consistit in extractionc
fluentis quantitatis ex asquatione simul involvente fluxionum ejus: altera tantum in assump-
tione Seriei pro quantitate qualibet incognita ex qua caetera commoda derivari possunt, et in
collatione terminorum homologorum aequationis resultantis, ad eruendos terminos assumptae
Seriei (Commercium Epistolicum, ed. 1722, p. 144).

CHEMISTRY AND MATHEMATICS

191

any way, than write it over again, being at present otherwise en¬
cumbered. Sir, I am in great haste,

y° urs ’ Is. Newton.

P. S. I hope this will so far satisfy M. Leibniz, that it will not be
necessary for me to write any more about this subject; for having
other things in my head, it proved an unwelcome interruption to
me to be at this time put upon considering these things. 43

The correspondence, from which I have derived my account of the
friendly and appreciative relations between Newton and Leibniz, is
of the greatest importance in his life. The letters are all preserved
in the Letter-Books of the Royal Society and were, when the con¬
troversy about the invention of the calculus broke out, examined and
certified by its Committee appointed to decide on the question of
priority. They were printed, in whole or in extracts, in the Com-
mercium Epistolicum and were adduced as the principal evidence
of Newton’s priority, and of Leibniz’s plagiarism. Of Newton s
priority, there could have been little doubt and Leibniz had frankly
admitted it; but the partisans of Newton, with his approval, at¬
tempted to disgrace Leibniz’s reputation on evidence taken prin¬
cipally from the epistola prior and the epistola posterior from which
I have just given extracts. It was claimed that a man of Leibniz’s
genius could have discovered the secret of the fluxional method from
the epistola posterior of October 24th; although it is now generally
conceded that it does not refer to that method. It is evident Newton
was certain that he had successfully concealed his method by his
jumble of letters and had, at the same time, given warning of his
priority to possible other discoverers, or why should he have em¬
ployed that stratagem ? These jumbled letters have been frequently
referred to, even by so recent writers as Brewster, as ciphers, or
anagrams, or transposed letters, which of course they are not. The
significance of such a designation is only too obvious. A cipher has a
key, and is not only capable of solution, but often is worked out by
others; thus the impression is made on the mind of the unwary that

43 Macclesfield, vol. II, p. 400.—Rigaud, the editor of the Collection remarks in a foot-note,
“There is no address to this letter. It seems to have been written to Collins, from the subject
of the preceding communication; and there are a number of figures in Collins’s handwriting
on the back.” To me, however, it seems far more likely to have been written to Oldenburg.
It was dated the same day as the epistola posterior to Oldenburg and has all the signs of being
a personal note referring to the letter to be forwarded to Leibniz. Edleston ( cf . p. li, note
55) is also of the sgme opinion.

ISAAC NEWTON

192

in some way Leibniz might have deciphered the sentences and so
have got information from them. Now, it is evident that no transla¬
tion could by any possibility be made, and it was intended by the
author that no one should be able to make any sense out of it till he
chose to publish his key sentences. Furthermore, no mathematician
could have obtained any help from such brief and obscure sentences
if they had been written in plain English. While the partisans of
Newton hinted that, in some way, Leibniz had received a clue from
Newton which enabled him to hit upon the invention of the calculus,
they were cautious enough to avoid being explicit in the charge,
only Raphson had the audacity to state that Leibniz had re-dis¬
tributed the jumble of letters and from the hidden sentences had
found his method. Raphson, in 1715, published a short History of
Fluxions and, with the permission of Newton, added some of the
correspondence and documents on the controversy. In the Preface
is the following outrageous statement: “He [Newton] communi¬
cated the same [his general method of quadratures] in a letter in the
year 1676 to Mr. Leibniz (of Germany) in letters transposed [sic]
as underneath [6a, etc.], which Mr. Leibniz having deciphered,
found this sentence contained under them, viz. [Data . . . vice
versa]: In English thus, [Having . . . vice versa\ \ and, some time
after, he perceived his meaning in it, and writ in answer that he had
found out a method not unlike it, as Sir Isaac himself had hinted,
p. 253, Princ. Phil. Nat. Math., but deferred publishing anything of
his own invention, till the month of October, in the year 1684.” 44

Unfortunately for the reputation of the partisans of Newton and
even more unfortunately for his own, the above does not cover the
facts. The time between Newton’s epistola posterior of 24 October,

44 Raphson, History of Fluxions, London, 1715. In the same year, a Latin translation was
published. Some copies have letters of Wallis, Leibniz, and Newton, added as an appendix.

I was able to secure copies of the Latin edition with, and without, the letters. But the Eng¬
lish edition is extremely rare and I desire to thank the Director of the British Museum for his
courtesy in sending me a photostatic copy of the part I needed. De Morgan calls Raphson
the unscrupulous man of the time. His unscrupulous statement of the deciphering the sen¬
tences, and the equally false one that Newton had hinted in the Principia, whereas he had
generously acknowledged, Leibniz’s independent discovery, justify the epithet. It may be
added, that Raphson changed and softened the charge of plagiarism in his Latin edition. In
that edition he omitted the statement that Leibniz “deciphered” the sentence and uses only the
expression, “Mente Newtoni ex epistolis ejus percepta”; also he omitted the word hinted and
merely states, “Newtonus ergo Ann. 1665, et 1666, methodum adinvenerit, et anno 1676,
notitias suae inventionis inter caeteros e [ e foot-note. Princ. Nat. Ph. Math. p. 253] cum Leib-
nitio communicaverit.” Raphson was sly enough to think that English readers would stand
a stronger dose than foreigners. As Newton gave to Raphson the documents, which he pub¬
lished, it is more than probable that he knew, and approved of, the contents of the book.

CHEMISTRY AND MATHEMATICS 193

1676, and the announcement to Oldenburg by Leibniz of his dis¬
covery of the Differential Calculus on 21 June, 1677, would have
been absurdly short for him to have invented the calculus even if he
had deciphered Newton’s sentences. But, the fact is, the forwarding
of Newton’s letter was delayed for months. This is verified by
incontestable evidence. Brewster, whose integrity forbade him to
ignore facts and yet whose partisanship was so strong that his entire
account of the controversy favours Newton or, at least, softens the
faults of his own, and of his British contemporaries’ conduct, can
be quoted with safety. “This letter,” he states, though dated 24th
October, (1676), had not been forwarded to Leibniz on the 5^
March, 1676/7. At the time Newton was writing it, Leibniz spent
a week in London, on his return from Paris to Germany, but it must
have reached him in the spring of that year, as he sent an answer to
it dated June 21, 1677.” 40 In other words, Leibniz had at his disposal
less than four months to force a meaning out of a mere jumble of
letters, which if straightened out would give but a vague hint, and to
develop out of this hint a finished mathematical analysis! For, in
his answer he frankly described his differential calculus, gave its
algorithm, or symbolic nomenclature, so perfectly that it is used to¬
day, and expressed his opinion that the method of drawing tangents
which Newton wished to conceal did not differ from his own.

We may assume that, during his week s visit in London, Leibniz
enquired for further information about Newton’s method and, if
so, he must have become convinced that he could not expect to over¬
come Newton’s innate reluctance to disclose his thoughts. He could
then, with perfect propriety, feel that the field was open to anyone
interested in the subject. So many were engaged along similar lines
that, if he would reap the honour of his great discovery, he must dis¬
regard the fact, which he suspected, that Newton’s method was
essentially similar to his own, and not delay longer to complete his

own work. ,

Be this as it may, Leibniz had invented the differential calculus by

his own efforts, as is now admitted by all unbiased and competent
critics. Soon after the receipt of Newton’s delayed epistola posterior,
he sent his answer on 21 June, 1677, addressed to Oldenburg. He
began the letter with a compliment to Newton: “I received your
long expected letter with the enclosed most excellent one from New¬
ton, which I shall read at once with the care and attention that it

45 Brewster, vol. II, p. 26..

194

ISAAC NEWTON

certainly merits, no less than it needs. Now, I shall note down
immediately a few points that occurred to me at a first glance. I am
immensely pleased that he has described the method by which he
arrived at some of his truly elegant theorems.” He then, as frank as
Newton was secretive, gave a full and clear statement of his com¬
plete differential calculus, with the notation still in use, so that others
could readily work with it. This letter, undoubtedly, marks an
epoch in pure mathematics as notable as that of Newton’s Principle*
in the physical sciences.

We should bear in mind that the relations between Newton and
Leibniz, at this time, were friendly and harmonious. Their corre¬
spondence was carried on through the intermediation of their
mutual friends Collins and Oldenburg, the latter of whom was the
countryman and deep admirer of Leibniz. The letters which passed
were couched in the stately manner of the day, and expressed full
recognition of each other’s commanding ability. Leibniz was frank
and eager in his desire to know what Newton had done; he showed
no jealousy, and readily admitted the claims of Collins and Olden¬
burg that Newton had been first in the field. On the other hand,
Newton was surprisingly indifferent, he never once asked his rival
to explain his method; he had to be urged to write at all and, when
he did so, the impression is given that he was bored and looked upon
the subject as of little interest. Certainly, we can find no trace of a
feeling, that he felt any obligation to give to the public a new, and
powerful, mathematical tool. It is one of the most baffling and in¬
explicable incidents in the history of science.

It was years later, after the calculus of Leibniz had established its
value on the continent, that the friends of Newton published his
prior claim, and he was aroused sufficiently to assert himself. Even
then, he did not publish his method with a notation so that others
could use it, he merely claimed that it was his property, and that no
other person was entitled to any share of the honour. The friends,
who urged him to assert himself, were the companions of his later
years, and the active ones amongst them, Fatio de Duillier, Raphson,
and Keill, were flatterers who could profit from his great reputation.
Their aim was not to establish Newton’s priority of discovery, that
was not disputed, but to strip from Leibniz every shred of merit by
accusing him of plagiarism of the most inexcusable kind,—of having
stolen Newton’s ideas from personal letters solicited from him, and
from private conversations with his friends. If Collins and Olden-

CHEMISTRY AND MATHEMATICS 195

burg had been alive at the time, those jackals of the lion would not
have dared to pursue their concerted plan to smirch the reputation

of one of the greatest ornaments of the age.

We shall have to apportion blame, and much blame, to both of
the principals of the controversy but we fortunately do not have to
question the direct statements of fact of either of them. If there had
been no documentary evidence that Newton had discovered the
germ of the fluxional calculus in 1665 or 1666, our knowledge of his
intellectual integrity would lead us to give full credit to his assertion.
And we ought also to give an unqualified acquiescence to the solemn
statement of Leibniz: “II n’y a pas,” he wrote in a letter to the Abbe
Conti, 46 “la moindre trace ni ombre du calcul des Differences ou
Fluxions dans toutes les anciennes Lettres de M. Newton que j’ai
vues, excepte dans celle qu’il a ecrite le 24 d’Octobre 1676, ou il n en
a parle que par enigme; et la solution de cette enigme, qu il n a
donnee que dix ans apres, dit quelque chose, mais elle ne dit pas

tout ce qu’on pourroit demander.”

This belief in their direct statements does not preclude the beliet
that they may have received, unconsciously, aid from each other.
The subject was in the air. It was from reading the Arithmetica of
Wallis, and the work of Fermat, that Newton turned his attention
to the subject of infinite series and found the idea of his calculus;
Leibniz had his interest aroused in the same subject by Huygens
and Pascal, and the mere knowledge, that Newton had found a
new method, may have given him an additional stimulus. The
opinion of the mathematician, Bernoulli, should be given weight;
it was his belief that, of the two, Newton received more assistance
from Leibniz. I am inclined to agree with that opinion so far as the
later development of fluxions is concerned. The work of Leibniz
was much more systematically developed; it could be quickly under¬
stood and extensively used by others. Newton’s methods were sui
generis, he could use them, but others could not. He never worked
out his methods in detail and it took years for others to learn to
follow his processes. There can be no doubt that some, at least, of
the theorems of his Principia were worked first by the fluxional
method and that he destroyed the evidence of its use when he
recast them in the classic geometric form. Before he was engaged
on that work, he had had Leibniz’s letter giving clearly his method
of the calculus, which he acknowledged in a Lemma. Would he not

46 Gerhardt, Briefwechsel Liebniz, Bd. I, p. 283.

196

ISAAC NEWTON

have improved his own method by adopting something from the
more systematic method and notation of his rival?

There is but little to add, at this time, to this episode in Newton’s
life. He had exhausted any interest he had had in the subject when
he wrote his epistola posterior of over fourteen folio pages to Leibniz;
and he announced his purpose to be quit of it forever in the note of
the same date which has been quoted. Although Collins then tried
to move him from this unfortunate decision, his plea was unavail¬
ing; the following reply left no doubt that Newton’s decision was
final.

Newton to Collins

Cambridge, Novemb. 8, 1676.

You seem to desire that I would publish my method, and I look
upon your advice as an act of singular friendship, being, I believe,
censured by divers for my scattered letters in the Transactions about
such things, as nobody else would have let come out, without a
substantial discourse. I could wish I could retract what has been
done, but by that I have learned what is to my convenience, which
is to let what I write lie by till I am out of the way. As for the appre¬
hension that M. Leibniz s method may be more general, or more easy
than mine, you will not find any such thing. His observation, about
reducing all roots to fractions, is a very ingenious one, and certainly
his way of extracting adfected roots is beyond it: but in order to
series they seem to me laborious enough in comparison of the ways
I follow, though for other ends they may be of excellent use. ... I
say there is no such curve line, but I can, in less than half a quarter
of an hour, tell whether it may be squared, or what are the simplest
figures it may be compared with, be those figures conic sections or
others. And then, by a direct and short way, (I dare say the shortest
the nature of the thing admits of, for a general one,) I can compare
them. And so, if any two figures expressed by such equations be
propounded, I can by the same rule compare them, if they may be
compared. This may seem a bold assertion, because it is hard to
say a figure may or may not be squared or compared] with another,
but it is plain to me by the fountain I] draw it from, thou[gh] I
will not undertake to prove it to others. The same method extends

CHEMISTRY AND MATHEMATICS

197

to equations of four terms, and others also, but not so generally. But
I shall say not more at present, but that I am,

your’s to serve you,

Is. Newton. 47

This determination to avoid making public his ideas had gone
much further than merely to break off his correspondence with
Leibniz; it made Newton resolve to forsake science altogether as a
profession, and it foreshadowed his later eagerness to leave Cam¬
bridge and to enter public life. Lest there should be any doubt of
the finality of his decision, he wrote a few days later to Oldenburg
the letter previously quoted 48 which expresses only too clearly the
bitterness that had replaced his ingenuous enthusiasm: “I see I have
made myself a slave to philosophy, but if I get free of Mr. Linus’s
business, I will resolutely bid adieu to it eternally, excepting what I
do for my private satisfaction, or leave to come out after me; for I
see a man must either resolve to put out nothing new, or to become
a slave to defend it.” The pity of it is that, judged on ordinary
standards, we can feel no justification for his disgust but, under the
cold and restrained demeanour of Newton there must have lain
hidden a hypersensitive spirit which shrank from the rough contacts
of life. And while we must, at times, judge his conduct adversely,
we must not forget the delicate organisation of his mind, nor the
self-discipline which overcame his natural temperament. In spite of
the fact that he was spurred on neither by ambition nor pleasure, he
later gave to the world his incomparable Principia and Optics. And
we can be grateful that his genius was recognised, and that he was
given during his life the homage which he deserved.

This year Newton contributed ^40 towards the building of the
new college library which was slowly approaching completion. One
other incident may be mentioned; Collins wrote to him that Loggan
had reported that he was engraving a portrait of Newton which was
to be prefixed to a treatise on light and colours. 49

Newton’s determination to be quit of scientific correspondence,

47 Macclesfield, II, p. 403. 48 Cf. Chapter IV, p. 91.

49 David Loggan was then engaged in making his plates for his Cantabrigia lllustrata. His
Plate of St. Mary’s Church was dedicated to Newton in the following style: “Clariss 0 . Viro D°.
Isaaco Newton Matheseos apud Cantabrigienses Professori Lucasiano SS tae Trinitatis Coll n
ibidem, et Regies Society Socio, Mathematico Philosopho, Chymico consummates 0 . ^Nec minus
suavitate Morum et Candore Animi, Cum rerum Humanarum Divinarumq: Peritia spectabili,
Hanc Tabulam Observantiae ergo D. D. C. Q. Dav. Loggan.” Edleston, note 61. Loggan has
left little unsaid in praise of his patron.

198

ISAAC NEWTON

which he had so often before threatened, he now carried out literally,
and for some years his life is practically concealed from us. Al¬
though Leibniz wrote at least two more letters, they were not an¬
swered. The death of Oldenburg may have been partly the cause,
but it is more probable that the correspondence would have stopped
under any circumstances.

During the next two years he was absent from college several
times but where he was, or what engaged his time and thoughts, we
do not know.

CHAPTER VII

LIFE IN CAMBRIDGE. ON THE NATURE OF THE TETHER.
FRIENDSHIP WITH MONTAGUE. EARLY WORK

ON GRAVITATION

1676-1685

H owever retired and isolated Newton’s life in Cambridge un¬
doubtedly was, he had, till the age of thirty-five, three
sources of contact with the scientific world,—Barrow,
Oldenburg, and Collins; but he was destined to lose all three in the
short space of a year. The unexpected death of Isaac Barrow, in
1677, at the early age of forty-seven was noted by Collins in a letter
to a friend: “Lamentation makes the next paragraph. The most
learned and pious Dr. Barrow, Master of Trinity College in Cam¬
bridge, coming up to make the customary Easter election of some
Westminster boys, to be admitted into the University, did here fall
sick of a malignant fever, which ended his days, to the very great
grief of all, that either knew or heard of his worth.” He was one of
the most versatile and distinguished men of his age: as a theologian,
his sermons are masterpieces of virile English and are still read with
interest and profit; as an administrator, he was rapidly restoring
Trinity College to its former prestige; as a mathematician and clas¬
sical scholar he attained a leading position. But his value to the world
came no less from the fact that he was the patron and friend of
Newton. That his unfailing help was appreciated is shown by the
brief statement made by Newton to Conduitt, many years later,
when he remarked that no one had greater cause to regret Barrow’s
death than he. 1 Barrow was Master of Trinity only five years, too
short a period to effect a permanent reform and, after his death, the
College declined in influence during the remainder of Newton’s life
in Cambridge. It is reasonable to suppose that this state of affairs
contributed to his desire to leave the University and the scholarly
life. In spite of Newton’s apparent detachment from society, he must
already have impressed influential men not only with his profound

1 Portsmouth Collection.

199

200

ISAAC NEWTON

scholarship, but also with his common sense and executive ability.
In confirmation of this opinion, I found the hitherto unpublished
memorandum by Conduitt in the Portsmouth Collection: “Arch¬
bishop Tenison offered him the Mastership [of Trijnity College
when it was given [to John Mjontague if he would take orders.” As
Montague was the successor of Barrow, this offer must refer to this
time. It certainly throws a new light on Newton’s standing and
influence in the University.

Till the year 1678 all of Newton’s correspondence with the Royal
Society, and with men of science, had been conducted through the
friendly mediation of Henry Oldenburg and John Collins. The al¬
most simultaneous loss of their stimulating influence accounts for
the sudden cessation of his correspondence till he found their suc¬
cessor in Edmond Halley, two years later.

Oldenburg (1626-1678) was born in Bremen and according to the
fashion of the day, assumed sometimes the transliterated name of
Grubendol. For several years, he acted as agent, or consul, for the
republic of Lower Saxony in England, and afterwards continued to
live in that country. His interest in science dates from his entry in
Oxford as a student; in 1662 he became Secretary of the Royal
Society. Much of the growth and success of the Society in its early
days is due to his love and indefatigable zeal for its interests. For
years, he worked for no compensation but the proceeds from the sale
of the Transactions which never amounted to more than ^40 a
year; afterwards he received an additional salary of the same amount.
He was a voluminous correspondent, serving as the medium of
scientific news between England and the Continent, and he edited
the first twelve volumes containing 142 numbers of the Transactions .

A letter from him to Boyle throws an interesting light on the
terrors of the plague and shows that he, like Pepys, was ready to risk
death in the discharge of his duties: “If the plague should come into
this row where I am, I think I should then change my thoughts and
retire into the country, if I could find a sojourning corner. In the
meantime, I am not a little perplexed concerning the books and
papers belonging to the Society that are in my custody; all I can
think of to do in this case is, to make a list of them all, and to put
them up by themselves in a box, and seal them together with a
superscription, that so in case the Lord should visit me, as soon as I
find myself not well, it may be sent away out of mine to a sound
house, and sic deinceps.”

LIFE IN CAMBRIDGE

201

Oldenburg’s passion for letter writing involved him in an un¬
expected and serious difficulty. His large foreign correspondence
awoke the suspicions of government officials who, in those corrupt
and unsettled times, could imagine no reason for communicating
with foreigners except to betray political information for money.
He was arrested on the following warrant:

C. R.

Warrant to seize the person of Henry Oldenburg for dangerous
designs and practices, and to convey him to the Tower.

June 20, 1667 By or( j er

Arlington.

Pepys, who rarely missed a bit of gossip, noted in his Diary five
days later: “I was told, yesterday, that Mr. Oldenburg, our Secretary
at Gresham College, was put into the Tower, for writing news to
a virtuoso in France, with whom he constantly corresponds on
philosophical matters; which makes it very unsafe at this time to
write, or almost do any thing.” 2 He was not released until August
26, and even a short imprisonment on a vague political charge was
a matter likely to have serious results. “I was so stifled,” he wrote
to Boyle, “by the prison-air, that, as soon as I had my enlargement
from the Tower, I widen’d it, and took it from London into the
country, to fan myself for some days in the good air of Craford in
Kent. Being now returned, and having recovered my stomach,
which I had in a manner quite lost, I intend, if God will, to fall to
my old trade, if I have any support to follow it. My late misfortune,
I fear, will much prejudice me; many persons unacquainted with
me, and hearing me to be a stranger, being apt to derive a suspicion
upon me. Not a few came to the Tower, merely to enquire after
my crime and to see the warrant, in which when they found that it
was for dangerous designs and practices, they spread it over London,
and made others have no good opinion of me.”

Oldenburg not only did yeoman service in promoting the scien¬
tific reputation of the Society, but he had to struggle against its
imminent dissolution from poverty. Dues were always sadly in
arrears, and he and Hooke were given a mere pittance, in spite of
the devotion of their entire lives to its furtherance,—their ability to

2 Weld, who quotes this passage from Pepys’s Diary, wrongly gives the date June 28.

202

ISAAC NEWTON

live on £80 a year, or less, is an interesting side-light on the sup¬
position of Newton’s resignation from inability to pay the fees. In
addition, he had to meet criticism from within and from without.
He and Hooke, his rival in the active management of the Society’s
affairs, were jealous of each other and caused dissensions amongst
the members. Once, at least, their mutual dislike broke out into an
open accusation by Hooke, that his invention of the coiled spring
for driving clocks had been maliciously assigned to Huygens and so
published by the Secretary in the Transactions . It is significant that
the Council publicly exonerated Oldenburg. Some, also, of its mem¬
bers were doubtful of the wisdom of an organised scientific body,
which might become the dictator of scientific thought and publica¬
tion. The most influential man of science of the day, Robert Boyle,
was certainly luke-warm towards it and, in letters to him, Olden¬
burg tried to remove his scruples. Boyle, like Hooke and Newton,
was intensely religious and considered the chief purpose of scientific
discovery to be the means of disclosing the design and laws of God.
The imminence and awe of the Divine Power were so real and so
constantly present with Boyle that he is said never to have failed to
make a distinct pause in his conversation before uttering the name of
God, and he had conscientious scruples against binding himself by
an oath. He, gradually, became a supporter of the Society, but he
declined the presidency for reasons which shew his extreme ten¬
derness and delicacy in all matters of conscience.” He wrote to his
much respected friend, Hooke, “hearing that an acquaintance of
mine was come to town, whose eminent skill in the law had made
him a judge, if he himself had not declined to be one, I desired his
advice (which because he would not send me till he had perused the
Society’s charter, I received not till late last night) and by it I found,
that he concurred in opinion with the two lawyers already men¬
tioned, and would not have me venture upon the supposition of my
being unconcerned in an act of parliament, to whose breach such
heavy penalties are annexed. His reasons I have not now time to tell
you, but they are of such weight with me, who have a great (and
perhaps peculiar) tenderness in point of oaths, that I must humbly
beg the Royal Society to proceed to a new election, and to so easy a
thing, as among so many worthy persons, that compose that illus¬
trious company, to choose a president, that may be better qualified
than I for so weighty an employment.” 3

3 Life of Boyle — Boyle's Wor\$, Vol. I, p. cxix.

LIFE IN CAMBRIDGE

203

Besides the indifference of many of the members and the reluc¬
tance to pay their dues, the Society aroused the jealousy and the
fears of the fundamentalists of the day, who accused the Fellows, in
print, with undermining the Universities, destroying the established
religion, and upsetting the ancient and solid learning. To meet such
attacks, Bishop Sprat published a history of the Royal Society and
Glanville wrote his Plus Ultra, in which he affirms that “the im¬
pertinent taunts of those who accused the Society of doing nothing
to advance knowledge, were no more to be regarded than the little
chat of idiots and children.” The amiable John Evelyn did not hes¬
itate to implicate the Devil in these plots against the New Learning.
“There is nothing,” we find in his Diary, “which does more confirm
me in the nobleness of the design, than this spirit of contradiction
which the Devil (who hates all discoveries of those false and presti¬
gious ways that have hitherto obtain’d), does incite to stir up men
against it.” Oldenburg, also, came to the defense of the Society in
his preface to the fifth volume of the Transactions. “Let envy snarl,”
he wrote, “it cannot stop the wheels of active philosophy in no [sic]
part of the known world.” Fie then gave a list of the nations which
had felt the stir of the new science, and added, “even the frozen
Muscovite and Russian, have all taken the operative ferment, and
it works high, and prevails every way to the encouragement of all
sincere lovers of knowledge and virtue.”

Oldenburg’s death naturally caused changes in the Royal Society.
Dr. Nehemiah Grew and Robert Flooke were elected joint Secre¬
taries, and the publication of the Transactions was suspended the
following year. In 1679, Flooke commenced publishing the Phil¬
osophical Collections, “a sheet or two every fortnight, of such
philosophical matters as he shall meet with from his correspondents.”
This abbreviated edition continued until 1683, when the Transac¬
tions were started again under the editorship of Dr. Plot, the suc¬
cessor of Flooke, and have continued without a break to the present
time.

The permanent break-down in health of Collins was perhaps an
even greater loss to Newton than the death of Oldenburg. Collins
writing to the mathematician, Thomas Strode, mentioned that he
had been prevented from being with Leibniz during his short visit
to London in October, 1676, because, “troubled with a scorbutic
humour, or saltness of the blood, and, taking remedies for it, they
made me ulcerous and in an uneasy condition.” And again, three

204

ISAAC NEWTON

months later, he was still suffering: “In this severe winter I have
been troubled with an ebullition of the blood caused by its thinness
and saltness, whence ensued a great itching, to remove which taking
physic before phlebotomy, it caused boils and an inflammation in
my right arm, which hindered not only all correspondence with
you ever since August last, but likewise my private affairs, being out
of the farthing office, or public concern, on account of tin farthings
that are to ensue.” Although Collins lived until November io, 1683,
the drastic physicking of the day had done its deadly work; his corre¬
spondence ceased, and his last years were evidently a period of suf¬
fering and debility. His last relation with Newton was characteristic
of him, as he offered to print his Algebra along with Wallis’s and
Barrow’s if the Royal Society would agree to subscribe for sixty
copies.

No history of science in the seventeenth century would be satis¬
factory which did not take notice of the activities of John Collins.
Although he was a self-educated man, knowing no Greek and but
little Latin, he attained to a mastery of science such that he corre¬
sponded constantly, and on terms of easy familiarity, with nearly
all the important scientists. He criticised their work with skill and
with the greatest tact; and he had a genius for getting information
about new books, passing it on to his friends and acting as an agent
for their purchase and sale. Styling himself a “midwife for the
press,” he published and edited scientific books, which were too
limited in sale to tempt the commercial printers and publishers. He
left behind him a large correspondence, docketed and annotated
with clerkly neatness, which now forms a part of the valuable scien¬
tific correspondence known as the Macclesfield Collection. Collins
had an unerring flare for detecting and appreciating genius. He
quickly estimated Newton to be the greatest mathematician of the
age; but he also recognised the genius of Leibniz and could ap¬
preciate that, as a creator of a new calculus, his systematic mind
would carry him further than the too individualistic temperament
of Newton. This may explain his apparently contradictory state¬
ment that Leibniz outtopped English mathematicians as a moon
amongst the lesser stars. 4 With his just estimate of the mental char¬
acteristics of the two rivals, and his intimate knowledge of the
opening scenes of the invention of the calculus, he would certainly
have prevented the tragic ending of the controversy. In my judge-

4 Macclesfield, vol. II, p. 454.

LIFE IN CAMBRIDGE

205

ment, Collins was the most valuable of Newton’s friends. One
needed to possess a cheerful disposition, a total lack of vanity, and
an unqualified appreciation of his transcendant powers, to penetrate
the reserved and timid shell which encrusted Newton’s otherwise
amiable character. Too many of those who sought his friendship did
so by unqualified flattery, in order to advance their own interests.

At this time, John Wickins was still the chamber-fellow of New¬
ton and perhaps continued so until he was presented to the living of
Stoke Edith, near Monmouth, in 1684. 5 Shortly after Newton’s
death, Conduitt began collecting materials for a proposed life of his
uncle and requested, by letters, any information that could be given.
It was natural to suppose that Wickins not only would have made
memoranda about their common life, but also would have passed
on to his family many anecdotes of their Cambridge days. Professor
Smith, then Lucasian Professor, wrote to his son for information.
To the everlasting reproach of the Wickins family the following
meagre account is all that could be extracted. It is exasperating that
the idea of preserving the habits and familiar talk of a Newton was
neglected for the duties of a rural parish, and that their most vivid
remembrance was of being aided in their dispensing of many dozens
of Bibles. The following letter is his reply:

Nic. Wickins to Professor Smith

Stoke Edith, Jan. 16th, 1827/8.

Dear Sir,—It was an unspeakable pleasure to me to see the hand of
my old acquaintance; and I wish, in return, I could send something
considerable to give you a pleasure relating to the great man you
write about, but I am so unhappy as to find very little under Sir
Isaac’s own hand of what passed between him and my father.

I guess from a small book I found among my father’s papers, that
he had a design to collect into one all that he had of Sir Isaac’s writ¬
ing, but he went no farther than transcribing three short letters he re¬
ceived from him, and a Common Place of his, part of which I find
under Sir Isaac’s own hand; the rest, with the original of these three
letters, is lost. Besides these transcribed letters and the Common
Place, I can meet with nothing but four or five letters under Sir
Isaac’s own hand, very short, and relating to dividends and chamber

5 Humphrey Newton, secretary to Newton, in 1685, states that he had no room-mate at
that time.

20 6

ISAAC NEWTON

rent, which he was so kind as to receive for my father when at Mon¬
mouth, where he was most part of the time he continued Fellow.
There being so little in these letters, I do not now send them, but
wait for your commands; for whatever I can meet with of this
worthy man, shall be at your service.

My father s intimacy with him came by mere accident. My
fathei s first chamber-fellow being very disagreeable to him, he re¬
tired one day into the walks, where he found Mr. Newton solitary
and dejected. Upon entering into discourse, they found their cause
of retirement the same, and thereupon agreed to shake off their
present disorderly companions and chum together, which they did
as soon as conveniently they could, and so continued as long as my
father staid at college.

I have heard my father often say that he has been a witness of
what the world has so often heard of Sir Isaac’s forgetfulness of his
food when intent upon his studies; and of his rising in a pleasant
manner with the satisfaction of having found out some proposition
without any concern for a seeming want of his night’s sleep, which
he was sensible he had lost thereby.

He was turning grey, I think, at thirty, and when my father ob¬
served that to him as the effect of his deep attention of mind, he
would jest with the experiments he made so often with quick-silver,
as if from hence he took so soon that colour. 6

He sometimes suspected himself to be inclining to a consumption,
and the medicine he made use of was the Leucatello’s Balsam, 7
which, when he had composed himself, he would now and then
melt in quantity about a quarter of a pint, and so drink it.

It is now eight years since my father’s death, in which time many
things my father used to relate of him are slipped out of my mem¬
ory; but being mostly of such a nature as I have now mentioned, I
suspect would be of no service could I recollect any more.

But there is one thing, upon account of which not only my father,
but myself also, shall always pay a peculiar regard to his memory,
which was a charitable benefaction which has privately passed from

6 Stukeley also refers to his white hair and assigns the cause to a hot and dry temperament.

Cf. Portsmouth Collection. y

7 Newton evidently thought the Balsam was a sovereign remedy for many ills since he
preserved its recipe in his papers. Its principal ingredient was what he calls Venus turpen¬
tine, a curious misspelling for Venice. He recommends “For the measell, plague, or small-

J ,1 ha k f - an T Ce in a llttle bro fh ; take it warm, and sweat after it. And against poison
and the biting of a mad dog; for the last you must dip lint and lay it upon the wound, be¬
sides taking it internally. There are other virtues of it; for wind, cholic, anoint the stomach,
and so tor bruises.

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207

him through my father’s, and since his death through my own
hands. We have been the dispensers of many dozens of Bibles sent
by him for poor people, and I have now many by me sent from him
for the same purpose, which, as it shows the great regard he had for
religion, I cannot but desire that by you it may be made public to
the world.

Dear Sir, my thoughts dwell with wonderful delight upon the
memory of this great and good man, and therefore I have troubled
you with so long a letter, which I now beg pardon for, and in hope
of again hearing soon from you, conclude with my brother’s hearty
service and respects to you. I beg my humble service to all my old
acquaintance, and am,

Dear Sir, your much obliged humble servant, j^ c Wickins

To Mr. Professor Smith, at

Trinity College, Cambridge. 8

Like many a bachelor scholar, Newton cultivated apprehensions
about his health, and had a fondness for dosing himself; Dr. Stuke-
ley, whom I have already quoted, says that “his breakfast was orange-
peel boiled in water, which he drank as tea, sweetened with sugar,
and with bread and butter. He thinks this dissolves phlegm.” And
Lord Pembroke told the Doctor that when Newton “got a cold, he
lay in bed till it was gone, though for two or three days’ continuance,
and thus came off the illness by perspiration.” 9 One can but wonder
what kind of a constitution he had. He was probably not robust,
and he was certainly lethargic in habit. He took no exercise, in¬
dulged in no amusements, kept no regular hours and was indifferent
to his food. Yet he lived to what, in that time, was an extraordinarily
old age with but one known serious illness, and his mind could
work indefinitely without any ill effects from lack of sleep or food.
His exemption from illness may be partly attributed to the simples
he concocted, and his avoidance of the drastic dosing and phle¬
botomy of medical practice.

Newton had now attained a position of authority, and he was
frequently solicited for advice and criticism. He was invariably
courteous in his answers to such enquiries and spared no pains to
give his opinions fully and clearly. It was a marked trait of his char¬
acter that he became bored by a scientific correspondence which in-

8 'Portsmouth Collection.

9 Portsmouth Collection.

208

ISAAC NEWTON

volved any enquiry or critical discussion of his own work; and he
soon declined to continue it on the plea that it distracted him. Yet he
would cheerfully interrupt his work in order to answer any requests
for information or help by others. Also, while correspondence of
the first sort was invariably carried on by an intermediary so that we
have scarcely a letter addressed to a well-known man of science, let¬
ters of the second sort were, on the contrary, sent direct to the en¬
quirer.

A Dr. Maddock had hit upon the idea that there might be radia¬
tions which would not affect sight, and sent to Newton some specu¬
lations on the properties of such dar\ rays. I should hardly look
upon this supposition of Dr. Maddock as a prophecy of our now
known electro-radiation any more than I think Anaximander was a
corner stone of evolution, because he opined that all life originated
in the ocean. In fact, Maddock seems to have based his hypothesis
on the legend that Tiberius, with his enormous protruding eyes,
could see at night and in the dark. Newton’s answer was eminently
kindly and tactful. He wrote that, unless some experimental evi¬
dence of such rays could be given, and it could be shown whether
they have the same laws of refrangibility as visible rays, or if not,
how they differ, then their existence must be doubtful. If, however,
he concluded, one grants the existence of such rays, the remainder
of your thesis is correct.

At what time Newton became interested in the problem of vision,
we do not know. But, that he had made dissections and careful
measurements of the optical system of the eye was proved by Brew¬
ster, who found amongst the family papers a drawing to scale of an
enlarged sheep’s eye with the dimensions tabulated. He had also
developed a theory of binocular vision which was later published as
Query 15 in his Optics. In 1682, Dr. William Briggs, Fellow of
Corpus Christi College, Cambridge, published a new theory of vision
in Hooke’s Philosophical Collections. He included a fantastic ex¬
planation of binocular sight, according to which the optic nerves
from corresponding points of the two retinas go to the brain in pairs
of equal length and tension. The nerve fibres, he further assumed,
are stretched like the strings of two harps and each pair of fibres of
equal length and tension give but one impression to the mind, as
two strings struck in unison seem but one sound. The author ap¬
pealed to Newton for criticism and, to his surprise, found that he
had been far surpassed in accuracy and breadth of knowledge of the

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subject. Newton answered with the freedom of a friend, praising
portions of what he politely named an ingenious theory, but making
it quite clear that he found this explanation of binocular vision to
be quite untenable. When Briggs pressed him to put his objections
in writing, he generously took the time to answer in a long letter,
covering in detail the whole subject, and incorporating his own ex¬
planation of binocular vision. According to his usual custom, he
began the letter with an apology, and a request that it be considered
confidential. “Though I am,” he wrote, “of all men grown the most
shy of setting pen to paper about any thing that may lead into dis¬
putes yet your friendship overcomes me so far as that I shall set
down my suspicions about your theory, yet in this condition, that
if I can but write plain enough to make you understand me, I may
leave all to your use without pressing it further on. For I design
not to confute or convince you but only to present and submit my
thoughts to your consideration and judgment.” He then, first, crit¬
icises adversely the hypothesis that the optic nerve fibres are under
different tensions according to their lengths by using a homely
illustration from the fibres of bent apple trees, a fact which must
have come under his acute observation in his boyhood. His own idea
of binocular vision was, that the object does not appear as one to the
mind because of the same colour, form, and bigness of the image in
each eye, but because the two images fall in the same relative situa¬
tions or places on the two retinas. His proof was that pressure on
one eye causes such coincident images to separate and one of them
will seem to move upwards, downwards, or sideways according to
the direction of the pressure applied to that eye. He then, wisely,
excluded the explanation of vision from the field of physics as being
a question to be answered only by a knowledge of the processes of
the mind.

In some unknown way, he thought the sensorium of the brain
interprets the two images as one, [perhaps by analogy to the inverted
images on the retina being interpreted in their correct position by
the mind]. “But you will say, how is this coincidence made? I
answer, what if I know not? Perhaps in the sensorium, after some
such way as the Cartesians would have believed, or by some other
way. Perhaps by the mixing of the marrow of the nerves in their
junction before they enter the brain, the fibres on the right side of
each eye going to the right side of the head, those on the left side to
the left.” After giving what facts he can to support his ideas he

210

ISAAC NEWTON

concluded: “You have now seen the sum of what I can think of
worth objecting, set down in a tumultuary way, as I could get time
from my Stourbridge Fair friends. If I have anywhere exprest my¬
self in a more peremptory way than becomes the weakness of the
argument pray look on that as done not in earnestness but for the
mode of discoursing. Whether any thing be so material as that it
may prove any way useful to you I cannot tell. But pray accept of
it as written for that end. For having laid philosophical speculations
aside, nothing but the gratification of a friend would easily invite
me to so large a scribble about things of this nature.”

As usually happens, the author paid little attention to his critic,
but continued in his own opinion. He published his Theory of
Vision in 1685, and prefixed to it a Latin letter by Newton. In the
same spirit with which Dr. Johnson wrote laudatory prefaces for all
sorts of books, Newton extolled Briggs’s theory of binocular vision
as similar to consonance of sounds, because Nature loves to accom¬
plish different ends by the same means. 10

Whenever a great advance is made in a particular subject of
physics, it naturally absorbs the attention not only of physicists, but
its influence spreads into the other sciences. Today, for example,
electrical phenomena are the most fertile field of study, and we are
making rapid advances in the discovery of new phenomena, the
formulation of new laws, and their application to the arts. During
such a period of expansion, there seems to be no limit to what may
be accomplished. In spite of past experience, we indulge the hope
that, at last, we have found a universal substance whose attributes
will account for all phenomena. Such systems were evolved in the
past with atoms of matter as the substratum of reality and, although
they failed, yet we are willing to begin again the same course of
speculation under the delusion that electricity, as a substance, may
evade the limitations which were discovered in matter. To be sure, ions
of electricity seem to be merely atoms of matter, reduced to a smaller
size and given a greater velocity; and their essential similarities are
disguised only by a change of name. Not only has electricity sup-

• .u T r F e A S f 0ndence T ! S pnnted , in ful ( m Edleston, pp. 264, 273, from the original MSS.
in the British Museum. Brewster also prints it with a comprehensive critique. Vol. I, pp.

2i« 236, 420-436 Those interested in the subject will find it well worth the study. In my
judgement, the subject of binocular vision lies, for the most part, outside the field of physics
and mechanics. After the image is formed on the retina, its future history and interpretation
as vision have no mechanical explanation. y

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211

planted matter as a basis of physical and chemical phenomena but
it somehow pleases us, or at least gives an anodyne to scepticism, to
say that nervous stimuli, the processes of life, and even consciousness,
are merely electrical actions. In the seventeenth century, due to the
invention of the air pump which enabled Boyle to vary, and to meas¬
ure, the pressure of gases, the properties of matter in the gaseous
state were enthusiastically investigated, and all phenomena, both of
the inorganic and organic worlds, were ascribed to modifications of
a subtile gas, or aether.

In Newton’s mind, there was gradually evolving a universal me¬
chanical system which would embrace all physical phenomena; the
postulates for this system required only the specification of inertia,
motion, and a force of attraction by a material substance. He had
found, from the criticism of his published work on light, that he
must postulate a luminiferous aether in order to account for such
phenomena as diffraction and the colours shown by thin transparent
films; his search for a general chemical principle had carried him
back to an atomic theory of matter; and lastly his discovery of an
universal law of gravitation had forced on him the dilemma of either
assuming for bodies an occult property of attracting at a distance,
or of postulating a gaseous medium which caused these attractions by
its pressure. Newton had met Robert Boyle, the acknowledged mas¬
ter of chemistry and the discoverer of the laws of gases, but a few
times. Their conversation turned on the properties of material gases
and on those of a universal aethereal gas which would serve as a sort
of dens ex machina of the physical world. Newton mentioned to him
his own idea of such an aether, and, at Boyle’s solicitation, he sent to
him an elaborate statement of his views of the constitution of such a
medium. The letter was first published in Boyle’s Wor\s and,
while it is quite long, it should be given with only the omission of
unimportant details as it is the fundamental document of the
mechanistic philosophy of the seventeenth and eighteenth centuries.

'Newton to Boyle

Honoured Sir,—I have so long deferred to send you my thoughts
about the physical qualities we spoke of, that did I not esteem myself
obliged by promise, I think I should be ashamed to send them at all.
The truth is, my notions about things of this kind are so indigested,
that I am not well satisfied myself in them; and what l am not satis -

212

ISAAC NEWTON

fied in, I can scarce esteem fit to be communicated to others;
especially in natural philosophy, where there is no end of fancying . n
But because I am indebted to you, and yesterday met with a friend,
Mr. Maulyverer, who told me he was going to London, and in¬
tended to give you the trouble of a visit, I could not forbear to take
the opportunity of conveying this to you by him.

It being only an explication of qualities which you desire of me, I
shall set down my apprehensions in the form of suppositions as fol¬
lows. And first, I suppose, that there is diffused through all places
an ethereal substance, capable of contraction and dilatation, strong¬
ly elastic, and, in a word, much like air in all respects, but far more
subtile.

2. I suppose this aether pervades all gross bodies, but yet so as to
stand rarer in their pores than in free spaces, and so much the rarer,
as their pores are less; and this I suppose (with others) to be the
cause why light incident on those bodies is refracted towards the
perpendicular; why two well-polished metals cohere in a receiver
exhausted of air; why mercury stands sometimes up to the top of a
glass pipe, though much higher than thirty inches; and one of the
main causes why the parts of all bodies cohere; also the cause of
filtration, and of the rising of water in small glass pipes above the
surface of the stagnating water they are dipped into; for I suspect the
aether may stand rarer, not only in the insensible pores of bodies,
but even in the very sensible cavities of those pipes; and the same
principle may cause menstruums [solvents] to pervade with violence
the pores of the bodies they dissolve, the surrounding aether, as well
as the atmosphere, pressing them together.

3. I suppose the rarer aether within bodies, and the denser with¬
out them, not to be terminated in a mathematical superficies, but to
grow gradually into one another; the external aether beginning to
grow rarer, and the internal to grow denser, at some little distance
from the superficies of the body, and running through all inter¬
mediate degrees of density in the intermediate spaces; and this may
be the cause why light, in Grimaldo’s experiment, passing by the edge
of a knife, or other opaque body, is turned aside, and as it were re¬
fracted, and by that refraction makes several colours. . ..

4. When two bodies moving towards one another come near to¬
gether, I suppose the aether between them to grow rarer than before,

11 Italics mine. One wonders whether those who are today so fancifully describing the
universe have satisfied themselves. If not, they might heed Newton’s advice with profit to
themselves and others.

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213

and the spaces of its graduated rarity to extend further from the
superficies of the bodies towards one another; and this, by reason that
the aether cannot move and play up and down so freely in the strait
[narrow] passage between the bodies, as it could before they came so
near together.... And as the other body approaches more and more,
I suppose the aether between them will grow rarer and rarer. These
suppositions I have so described, as if I thought the spaces of gradu¬
ated aether had precise limits. . . . But really I do not think they have
such precise limits, but rather decay insensibly, and, in so decaying,
extend to a much greater distance than can easily be believed or need
be supposed.

5. Now, from the fourth supposition it follows, that when two
bodies approaching one another come so near together as to make
the aether between them begin to rarefy, they will begin to have a
reluctance from being brought nearer together, and an endeavour to
recede from one another; which reluctance and endeavour will in¬
crease as they come nearer together, because thereby they cause the
interjacent aether to rarefy more and more. But at length, when
they come so near together that the excess of pressure of the external
aether which surrounds the bodies, above that of the rarefied aether,
which is between them, is so great as to overcome the reluctance
which the bodies have from being brought together; then will that
excess of pressure drive them with violence together, and make them
adhere strongly to one another, as was said in the second supposition.
. . . Now hence I conceive it is chiefly that a fly walks on water
without wetting her feet, and consequently without touching the
water; that two polished pieces of glass are not without pressure
brought to contact, no, not though the one be plain, the other a
little convex, that the particles of dust cannot by pressing be made
to cohere, as they would do, if they did but fully touch; that the par¬
ticles of tingeing substances and salts dissolved in water do not of
their own accord concrete and fall to the bottom, but diffuse them¬
selves all over the liquor, and expand still more if you add more
liquor to them. Also, that the particles of vapours, exhalations, and
air do stand at a distance from one another, and endeavour to recede
as far from one another as the pressure of the incumbent atmosphere
will let them; for I conceive the confused mass of vapours, air, and
exhalations which we call the atmosphere, to be nothing else but the
particles of all sorts of bodies, of which the earth consists, separated
from one another, and kept at a distance by the said principle.

214

ISAAC NEWTON

From these principles the actions of menstruums upon bodies may
be thus explained: suppose any tingeing body, as cochineal or log¬
wood be put into water; so soon as the water sinks into its pores and
wets on all sides any particle which adheres to the body only by the
principle in the second supposition, it takes off, or at least much
diminishes, the efficacy of that principle to hold the particle to the
body, because it makes the aether on all sides the particle to be of a
more uniform density than before. And then the particle being
shaken off by any little motion, floats in the water, and with many
such others makes a tincture; which tincture will be of some lively
colour, if the particles be all of the same size and density; otherwise
of a dirty one. For the colours of all natural bodies whatever seem
to depend on nothing but the various sizes and densities of their par¬
ticles, as I think you have seen described by me more at large in an¬
other paper. 12 .. .

Nor does the size only, but the density of the particles also, con¬
duce to the permanency of aerial substances; for the excess of density
of the aether without such particles above that of the aether within
them is still greater; which has made me sometimes think that the
true permanent air may be of a metallic origina; the particles of no
substances being more dense than those of metals. This, I think, is
also favoured by experience, for I remember I once read in the
Philosophical Transactions, how M. Huygens at Paris, found that
the air made by dissolving salt of tartar would in two or three days
time condense and fall down again, but the air made by dissolving a
metal continued without condensing or relenting in the least. If
you consider then, how by the continual fermentations made in the
bowels of the earth there are aerial substances raised out of all kinds
of bodies, all which together make the atmosphere, and that of all
these the metallic are the most permanent, you will not perhaps
think it absurd, that the most permanent part of the atmosphere,
which is the true air, should be constituted of these, especially since
they are the heaviest of all other, and so must subside to the lower
parts of the atmosphere and float upon the surface of the earth, and
buoy up the lighter exhalations and vapours to float in greatest plenty
above them. Thus, I say, it ought to be with the metallic exhalations
raised in the bowels of the earth by the action of acid menstruums,

12 Here follows a long passage giving many illustrations from various chemical actions to
show that they depend on the size of the particles, or atoms as we would say, and whether
the constituent substances are “sociable” or “unsociable” towards each other. These illustra¬
tions are ingenious, but obsolete, and may be omitted.

LIFE IN CAMBRIDGE

215

and thus it is with the true permanent air; for this, as in reason it
ought to be esteemed the most ponderous part of the atmosphere, be¬
cause the lowest, so it betrays its ponderosity by making vapours as¬
cend readily in it, by sustaining mists and clouds of snow, and by
buoying up gross and ponderous smoke. The air also is the most
gross unactive part of the atmosphere, affording living things no
nourishment, if deprived of the more tender exhalations and spirits
that float in it; and what more unactive and remote from nourish¬
ment than metallic bodies ?

I shall set down one conjecture more, which came into my mind
now as I was writing this letter; it is about the cause of gravity. For
this end I will suppose aether to consist of parts differing from one
another in subtilty by indefinite degrees; that in the pores of bodies
there is less of the grosser aether, in proportion to the finer, than in
open spaces; and consequently, that in the great body of the earth
there is much less of the grosser aether, in proportion to the finer,
than in the regions of the air; and that yet the grosser aether in the
air affects the upper regions of the earth, and the finer aether in the
earth the lower regions of the air, in such a manner, that from the top
of the air to the surface of the earth, and again from the surface of
the earth to the centre thereof, the aether is insensibly finer and
finer. Imagine now any body suspended in the air, or lying on the
earth, and the aether being by the hypothesis grosser in the pores,
which are in the upper parts of the body, than in those which are
in its lower parts, and that grosser aether being less apt to be lodged
in those pores than the finer aether below, it will endeavour to get
out and give way to the finer aether below, which cannot be, with¬
out the bodies descending to make room above for it to go out into.

From this supposed gradual subtilty of the parts of aether some
things above might be further illustrated and made more intelligible;
but by what has been said, you will easily discern whether in these
conjectures there be any degree of probability, which is all I aim at.
For my own part, I have so little fancy to things of this nature, that
had not your encouragement moved me to it, I should never, I think,
have thus far set pen to paper about them. What is amiss, therefore,
I hope you will the more easily pardon in

Your most humble servant and honourer,

Cambridge, Feb. 28, 1678/9. 13 Isaac Newton.

13 First published in Boyle’s Wor\s, Vol. I, p. cxii. Copied in Brewster, Vol., I, p. 409,
and Macclesfield, Vol. II, p. 407.

2 l6

ISAAC NEWTON

This year can be marked as a fortunate and influential one for
Newton, as it saw the beginning of a new relationship which was
destined to have a profound effect on all his future life. On Novem¬
ber 8, Charles Montague matriculated at Trinity College as a Fel¬
low-Commoner and, between the brilliant young man and the
Lucasian Professor nineteen years his senior, there quickly grew up a
friendship which was broken only by the death of Montague. It is
difficult to understand what drew two such unlike men together. It
must have been a strong tie, because in the beginning, one occupied
the position of an undergraduate student, and the other was one of
the distinguished scholars of the world; while later the positions
became reversed, and the younger man grew to be a great nobleman
and statesman, the patron and employer of his former master. Such
a reversal of fortune is not conducive to ingenuous friendship and, in
this case, it would have seemed to be especially unexpected, for one
was vain and arrogant, and the other vain and sensitive. Yet it did
last and, so far as we know, there was but one temporary display of
ill temper between them. To understand Newton’s life rightly, we
must know what manner of a man Montague was, and follow his
dazzling career.

Charles Montague, the fourth son of a younger son of the first earl
of Manchester, was born at Horton, Northamptonshire, in 1661, the
year Newton went to college. He was educated at Westminster
School, and then entered Trinity College. As a younger son, of a
younger branch of the family, he was not wealthy and was, like
many younger sons, intended for the church. He early showed great
ability and had evidently a warm and generous nature, for it was
told of him that he went to college a year before the proper time, as
he was unable to bear the thought of being separated from his “dear¬
est friend.” Although the cold facts of dates prove the story to be
apocryphal, we may rely on it as an expression of his unspoiled temp¬
erament and attribute his later pride and unpopularity to his heady
successes in politics. As a Fellow-Commoner, he would meet the
Fellows of the College intimately in hall and commons, and it was
during those times that his friendship with Newton would grow.
His career at College was a brilliant one as he surpassed his competi¬
tors in logic and ethics, and read widely in the classics. At the same
time, his attention was applied sufficiently to mathematics and science
for him to turn from the Cartesian system in vogue to the new
philosophy then being so brilliantly developed by Newton. His

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217

biographers say that “he was one of the small band of students who
assisted Newton in forming the Philosophical Society of Cam¬
bridge”; but we shall see, at the proper time, that the attempt failed.
In 1681, he was made M.A. by Royal Mandate, as befitted a young
gentleman of a noble family.

However able as a student Montague may have been, it was his
talent for fluent verse-making which opened up the way to fortune.
A clever and absurdly eulogistic ode, written on the death of
Charles II, 14 secured him favourable notice of the earl of Dorset, the
great patron of the day, who took him to London and introduced
him to the principal wits of the town. Although he had been a Fel¬
low of his college for some years past, we can be sure that he now
spent most of his time in London and, with powerful patronage be¬
hind him, began to look forward to making his fortune by his pen.
The opportunity came to him, and nothing is more surprising to us
than the sort of opportunities which then opened the road to polit¬
ical preferment; a clever lampoon or eulogy, an amorous intrigue, or
a genuine literary ability, all were regarded as the equipment for a
statesman, and oddly enough often correctly. Such an opportunity
came to him and to seize it he did not hesitate to enter the lists
against Dryden, the dictator of letters. With the accession of James
II, Dryden had become a Roman Catholic, some say from conviction,
and others to gain royal favour. However that may be, he wrote and
published The Hind and the Panther in which, with all the fervour
of a new convert, he portrayed the Roman Church as a timid and in¬
nocent hind drooping in the cruel jaws of a carnivorous and venge¬
ful Church of England. Montague saw his chance and, with the
collaboration of Matthew Prior whom he had recently met, he wrote
a parody on this ode, in 1687, which was called the Country Mouse
and the City Mouse. The burlesque carried the city by storm, and

14 As this ode started Montague on a career which incidentally made Newton Master of
the Mint, the reader may wish a specimen of it:

“Farewell, Great Charles, Monarch of Blest Renown,

The best Good Man that ever fill’d a Throne:

Whom Nature, as her highest Pattern, wrought
And mixt both Sexes Virtues in one Draught.

Wisdom for Councils, Bravery in War,

With all the mild Good-Nature of the Fair,

The Woman’s Sweetness, temper’d Manly Wit,

And Loving Power, did crown’d with Meekness fit;

His awful Person Reverence engag’d,

Which mild Address and Tenderness assuag’d:

Thus the Almighty Gracious King above,

Does both command our Fear, and win our Love.”

2 l8

ISAAC NEWTON

his reputation was made, not only as a man of letters but as a poten¬
tial statesman. The following year, he resigned his fellowship and
left Cambridge. As a further step towards fortune he married, at
about, the same time, the Countess Dowager of Manchester, his
uncle’s widow. We can be fairly certain that it was ambition rather
than affection which influenced him, as his wife was from ten to
twenty years older than himself and had borne nine children to her
first husband. In 1689, he became a member of the Convention Par¬
liament for Malden through the patronage of Dorset. Dr. Johnson
says that when he entered Parliament he still intended to take orders,
but his success as a debater turned him permanently to public life.
As during the sessions, he again met Newton, who had been elected
to represent the University, we can defer his future history. 15

The attention of the world has been so concentrated on Newton as
the scholar and man of science that another side of his character
has been neglected. He was known as a man of sound judgement
and of executive ability by his colleagues before he attained his com¬
manding reputation in science or he would not have been selected
by the University to serve as its representative during a delicate and
dangerous religious controversy with James II before the High
Court of Commission, and also in the Convention Parliament which
reorganised the government after the Revolution of 1687. We should
also remember that Montague, in his student days, had been so
impressed with the same qualities as later to entrust to him the com¬
plicated and hazardous problems of the recoinage. That he had a
strong pride of family and longed to be a gentleman of social rank
and gentle birth, as that title then signified, rather than to be a
scholar, is equally certain. He held stiffly to the distinction of his
lordship of a manor, insignificant as the manor was; he acted gen¬
erously towards the members of his family, whether they were
worthy or worthless, as would be becoming of the head of a county
family; and he endeavoured to trace his genealogy to another county
family of the same name, but of higher rank, on very doubtful ev¬
idence. And, lastly, he showed in the later period of his life the
greatest satisfaction as the dispenser of an easy hospitality, as the
companion of the gentry and nobility, and as the favourite of a very
dull Court. And when he became a gentleman, he abandoned science
and scholarship without any apparent regret. This opinion is given

15 See the Wor\s and Life of the Earl of Halifax. Printed for E. Curll, London, 1715.
A rare and not altogether reliable history as it was written in a tone of uncompromising
eulogy.

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219

without the least intention to cast a slur on Newton’s reputation or
character. If so, I should have to include Shakespeare, who also
abandoned his career and literary fame to be a landed gentleman; to
be a gentleman in those days meant much more than it does now,
and to be a scientist meant far less. Newton had the unusual dis¬
tinction of satisfying both ambitions.

It was this side of his character which his intimacy with Montague
brought to self-consciousness and to maturity. It was the first time
that the scholar had come in contact with what we call the great
world. The wit, the buoyancy of spirits, and the social manners of
this brilliant youth attracted and fascinated the college don. The
reminiscences we have give no details of this intimacy, but the
scholar’s long vigils of work must have been frequently broken by
conversations with his young friend. Although it is natural that his
scholarly habits should have been emphasized, he was not quite the
solitary figure he has been depicted, and his time was not entirely
absorbed in his laboratory and study. There were the almost daily
meetings with the Fellows in the Combination Room; he had a small
circle of acquaintances in the other colleges and occasional guests
from out of town; he frequently took part in the philosophical dis¬
cussions of the Platonists who made Christ Church their rendezvous.
Then, too, it should not be forgotten that Wickins, who was his
room-mate for many years and thus his constant companion, would
also bring his friends to their rooms. But most significant of all, the
intimacy with Montague points to frequent and familiar visits. We
can imagine that the brilliant young man would delight and charm
the older scholar with his wit and with his accounts of the country
life of a great house. And, in return, he would receive from Newton
a first hand knowledge of the new philosophy and the new science
which was stirring in the scholarly world. Nor should we doubt that
Newton described his personal work and sketched those ideas of a
cosmical system which were unfolding in his mind; and if so, there
were few to be more envied than he, who had the unique opportunity
of hearing those profound ideas at first hand, and in their inception.
The influence of Halley in giving us the publication of the Principia
has been frequently extolled; but no one has linked Montague’s
name with it; and yet his sympathy and eager enthusiasm may have
done much to encourage Newton during the early days of its incu¬
bation. We have suffered an irreparable loss by the failure of Monta¬
gue to leave us a record of his long and intimate association with

220

ISAAC NEWTON

Newton; how many disputed points such a record would have
solved.

The reconciliation with Hooke, which resulted from the exchange
of the courteous letters previously quoted, was only a temporary
truce. Their natures were too incompatible to endure any contact
with patience, and the first indication that Newton gave of a renewed
willingness to make public his ideas was certain to arouse the
watchful and jealous irritation of Hooke. The cause of the final and
permanent break between them arose from a casual suggestion made
by Newton to the Royal Society that it would be useful to undertake
an experiment on falling bodies. Although the result of the sugges¬
tion led to bitterness, it must be looked upon as one of the greatest
and most fortunate of events, since it was the direct cause of the com¬
position of the Principia.

Before giving the history of this episode, a summary of the prin¬
cipal questions involved will be useful. 16 A month after Oldenburg’s
death, Hooke, the new Secretary, wrote a courteous letter, at the re¬
quest of the Royal Society, begging Newton to continue his corre¬
spondence on scientific matters with its members, as it was feared
that his interest in its affairs might cease with the death of his friend.

Hoo\e to Neu/ton, Nov. 24, i6yg
Sir,

Finding by our registers that you were pledged to correspond with
Mr. Oldenburg, and having also had the happiness of receiving some
letters from you myself make me presume to trouble you with this
present scribble—Dr. Grew’s more urgent occasions having made
him decline the holding correspondence. And the Society hath de-

16 The sources of this most important event in Newton’s life are seven letters which passed
between Newton and Hooke in the years 1679 and 1680 and seventeen between Newton and
Halley in the years 1686 and 1687., Ball has published the Hooke-Newton correspondence
with the exception of two letters which had not been found; fortunately one of these, New¬
ton to Hooke, Dec. 13, 1679, has just been discovered and published with an interesting
comment on the whole incident by M. Pelseneer. This leaves only one letter, Hooke to New¬
ton, Dec. 9, 1679, unaccounted for, and its tenor is known from atn extract in the R. S.
Record. Of the seventeen letters of Halley and Newton relating to the publishing of the
Principia all but one, which was lost, are given in Ball’s Essay. The quarrel between New¬
ton and Hooke which occurred in the years 1679 and 1680 can be described from the con¬
temporary first series; as it flared up again when the Principia was published, Newton’s atti¬
tude can be seen in retrospect from his letters to Halley.. The reader should consult: W. W.
Rouse-Ball, Essay on Newton’s Principia, Macmillan, 1893.—Rigaud, First Publication of the
Principia, Oxford, 1838.—Jean Pelseneer, Une lettre inedite de Newton, Isis, Vol. XII (2),
No. 38, 1929.

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221

volved it on me. I hope therefore that you will please to continue
your former favours to the Society by communicating what shall oc¬
cur to you that is philosophical, and for return I shall be sure to ac¬
quaint you with what we shall receive considerable from other parts
or find out new here. And you may be assured that whatever shall
be so communicated shall be no otherwise further imparted or dis¬
posed of than you yourself shall prescribe. I am not ignorant that
both heretofore, and not long since also, there have been some who
have endeavoured to misrepresent me to you, and possibly they or
others have not been wanting to do the like to me, but difference in
opinion if such there be (especially in philosophical matters where
interest hath little concern) me thinks should not be the occasion of
enmity—’tis not with me I am sure. For my part I shall take it as a
great favour if you shall please to communicate by letter your objec¬
tions against any hypothesis or opinion of mine; and particularly if
you will let me know your thoughts of that of compounding the
celestial motions of the planets of a direct motion by the tangent and
an attractive motion towards the central body, or what objections you
have against my hypothesis of the laws or causes of springyness.

I have lately received from Paris a new hypothesis invented by Mo r
Mallemont de Messanges, D r of the Sorbonne, who desires much to
have what can be objected against it. He supposes then a centre of
this our vortex about which all the primary planets move in perfect
circles, each of them in his own equal spaces in equal times. The next
to it he places the Sun; and about the Sun, Mercury as a satellite;
the next Venus; the next the earth, about which the Moon as a
satellite; then Mars; then Jupiter and his satellites; and Saturn with
his. He supposes the Sun to make its revolution in about half the
time the earth makes its, and the plane of it to be inclined to the
plane of the ecliptic as much as the trepidation requires. He is not
precise in defining any thing, as reserving a liberty to himself to help
him out where objections might stick.

I am informed likewise from Paris that they are there about an¬
other work, viz. of settling the longitude and latitude of the most
considerable places: the former of those by the eclipses of the satellites
of Jupiter. M r Picart and De la Hire travel, and Mo r Cassini and
Romer observe at Paris. They have already found that Brest in Brit¬
tany is 18 leagues nearer Paris than all the maps make it. I have writ¬
ten to a correspondent in Devonshire to see if we can do somewhat

222

ISAAC NEWTON

of that kind here, and I should be glad if by perpendicular observa¬
tions, we could determine the difference of latitude between Lon¬
don and Cambridge. If you know of any one that will observe at
Cambridge, I will procure it to be done here very exactly.

M r Collins shewed me a book he received from Paris of De la Hire
containing first a new method of the conic sections and secondly a
treatise De locis solidis. I have not perused the book but M r Collins
commends it. M r Flamsteed by some late perpendicular observations
hath confirmed the parallax of the orb of the earth.

But I fear I have too much trespassed, and therefore to put an end
to your further trouble I shall subscribe myself, Sir,

Your very humble Servant,

Gresham Colledge, Nov. 24,1679. 17

As a personal document, this letter is important as it shows Hooke’s
better nature and amounts almost to an apology for his, and the
Society’s, past treatment of Newton. Philosophically it is much more
important. Hooke’s question about the law of attraction turned New¬
ton’s attention to his early work on the subject and induced him to
take it up again in a serious manner; the reference to Picart’s work
may have led him to substitute the more correct diameter of earth in
his former calculations of the attraction of the moon although I have
shown this not to be probable; and lastly, the hypothesis of Mes-
sanges 18 was the direct cause of the discovery of the law of attraction
of a solid sphere on an exterior or interior point—a theorem essential
to expanding the law of gravitation into one of universal applicability.

Newton answered Hooke’s letter almost immediately. It is one
of the most revealing documents we have from him, because of the
light it throws on his intentions for the future. There can be no rea¬
son to doubt that he had determined to abandon science and philos¬
ophy permanently. What his plans were, we shall probably never
know, but we can guess that he intended to follow Barrow into the

17 An Essay on Newton’s Principia, W. W. Rouse-Ball, p. 139.

18 The hypothesis of Messanges can be explained somewhat more clearly than it is in the
letter. Mallemont de Messanges published his Nouveau systeme du Monde in 1679, and im¬
mediately sent a copy to the Royal Society for criticism. He imagined that there was a fixed
centre of the solar system and that about it the planets were carried in exact circles by a Car¬
tesian vortex. The Sun, with Mercury as its moon, was the nearest of the planets to this im¬
aginary centre and the others at increasing distances were Venus, Mars, Earth, etc. The
revolution of the Sun required something more tha;n six months. The whole idea is, of
course, absurd; and when he later wrote a dissertation on comets, the astronomer Lalande
caustically remarked that “il n’est pas aussi absurde que de coutume.”

LIFE IN CAMBRIDGE

223

field of theology or to try to join Montague, as he afterwards did,
in some public career.

Newton to Hoo\e

Nov. 28, 1679. 10
Sir,

I cannot but acknowledge my self every way, by the kindness of
your letter, tempted to concur with your desires in a philosophical
correspondence. And heartily sorry I am that I am at present un¬
furnished with matter answerable to your expectations—for I have
been this last half year in Lincolnshire cumbered with concerns
amongst my relations till yesterday when I returned hither; so that I
have had no time to entertain philosophical meditations, or so much
as to study or mind any thing else but country affairs. And before
that, I had for some years last been endeavouring to bend myself
from philosophy to other studies in so much that I have long
grutched the time spent in that study unless it be perhaps at idle
hours sometimes for a diversion; which makes me almost wholly
unacquainted with what philosophers at London or abroad have of
late been employed about. And perhaps you will incline the more
to believe me when I tell you that I did not, before the receipt of
your last letter, so much as hear (that I remember) of your hypoth¬
esis of compounding the celestial motions of the planets, of a direct
motion by the tangent to the curve, and of the laws and causes of
springyness, though these no doubt are well known to the philos¬
ophical world. And having thus shook hands with philosophy and
being also at present taken of with other business, I hope it will not
be interpreted out of any unkindness to you or the R. Society that I
am backward in engaging my self in these matters, though formerly
I must acknowledge I was moved by other reasons to decline, as much
as M r Oldenburg’s importunity and ways to engage me in disputes
would permit, all correspondence with him about them. However I
cannot but return my hearty thanks for your thinking me worthy of
so noble a commerce and in order thereto frankly imparting to me
several things in your letter.

As to the hypothesis of Mons r Mallemont, though it should not be
true yet if it would answer to phenomena it would be very valuable
by reason of its simplicity. But how the orbits of all the primary

19 Rigaud in his Essay on the Principia gives a surprisingly accurate account of this episode
although he was compelled to reconstruct the story from very scanty materials since the letters
here quoted had not then been discovered., Brewster gives it but little space.

224

ISAAC NEWTON

planets but Mercury can be reduced to so many concentric circles
through each of which the planet moves equal spaces in equal times
(for that’s the hypothesis if I mistake not your description) I do not
yet understand. The readiest way to convince the world of this truth
would be I conceive to set forth first in some two of the planets, sup¬
pose Mars and the earth, a specimen thereof stated and determined
in numbers.

I know nobody in the University addicted to making astronomi¬
cal observations: and my own short sightedness and tenderness of
health makes me something unfit. Yet it’s likely I may sometime
this winter when I have more leisure than at present attempt what
you propound for determining the difference of latitude between
Cambridge and London.

I am glad to hear that so considerable a discovery as you made of
the earth’s annual parallax is seconded by M r Flamsteed’s observa¬
tions.

In requital of this advertisement I shall communicate to you a
fancy of my own about discovering the earth’s diurnal motion. In
order thereto I will consider the earth’s diurnal motion alone, with¬
out the annual, that having little influence on the experiment I
shall here propound. Suppose then BDG represents the globe of the
earth carried round once a day about its centre C from west to east
according to the order of the letters BDG; and let A be a heavy
body suspended in the air, and moving round with the earth so as
perpetually to hang over the same point thereof B. Then imagine
this body A [the MS. has B, which is obviously a slip] let fall, and
its gravity will give it a new motion towards the centre of the earth
without diminishing the old one from west to east. Whence the mo¬
tion of this body from west to east, by reason that before it fell it was
more distant from the centre of the earth than the parts of the earth
at which it arrives in its fall, will be greater than the motion from
west to east of the parts of the earth at which the body arrives in its
fall; and therefore it will not descend the perpendicular AC, but
outrunning the parts of the earth will shoot forward to the east side
of the perpendicular describing in its fall a spiral line ADEC, quite
contrary to the opinion of the vulgar who think that, if the earth
moved, heavy bodies in falling would be outrun by its parts and fall
on the west side of the perpendicular. The advance of the body from
the perpendicular eastward will in a descent of but twenty or thirty
yards be very small, and yet I am apt to think it may be enough to

LIFE IN CAMBRIDGE

225

determine the matter of fact. Suppose then in a very calm day a
pistol bullet were let down by a silk line from the top of a high
building or well, the line going through a small hole made in a plate
of brass or tin fastened to the top of the building or well, and that
the bullet when let down almost to the bottom were settled in water
so as to cease from swinging, and then let down further on an edge
of steel lying north and south to try if the bullet in settling thereon
will almost stand in aequilibrio but yet with some small propensity
(the smaller the better) decline to the west side of the steel as often
as it is so let down thereon. The steel being so placed underneath,
suppose the bullet be then drawn up to the top and let fall by cut¬
ting, slipping, or burning, the line of silk, and if it fall constantly on
the east side of the steel it will argue the diurnal motion of the earth.
But what the event will be I know not, having never attempted to
try it. If any body would think this worth their trial, the best way
in my opinion would be to try it in a high church or wide steeple,
the windows being first well stopped; for in a narrow well the
bullet possibly may be apt to receive a ply from the straitened air
near the sides of the well, if in its fall it come nearer to one side than
to another. It would be convenient also that the water into which
the bullet falls be a yard or two deep or more, partly that the bullet
may fall more gently on the steel, partly that the motion which it
has from west to east at its entering into the water may by means of
the longer time of descent through the water, carry it on further
eastward and so make the experiment more manifest.

If I were not so unhappy as to be unacquainted with your hypoth¬
esis abovementioned (as I am with almost all things which have of
late been done or attempted in philosophy) I should so far comply
with your desire as to send you what objections I could think of
against them, if I could think of any. And on the other hand I could
with pleasure hear and answer any objections made against any no¬
tions of mine in a transient discourse for a divertisement. But yet my
affection to philosophy being worn out, so that I am almost as little
concerned about it as one tradesman uses to be about another man’s
trade or a countryman about learning, I must acknowledge myself
averse from spending that time in writing about it which I think I
can spend otherwise more to my own content and the good of others:
and I hope neither you nor any body else will blame for this averse¬
ness. To let you see that it is not out of any shyness, reservedness, or
distrust that I have of late and still do decline phi[losophi]cal com-

226

ISAAC NEWTON

merce but only out of my applying myself to other things, I have
communicated to you the notion above set down (such as it is) con¬
cerning the descent of heavy bodies for proving the motion of the
earth; and shall be as ready to communicate in oral discourse any¬
thing I know, if it shall ever be my happiness to have familiar con¬
verse frequently with you. And possibly if anything useful to man¬
kind occurs to me I may sometimes impart it to you by letter. So
wishing you all happiness and success in your endeavours, I rest,

Sir,

Your humble Servant

to command
Is. Newton.

P. S. Mr. Cock has cast two pieces of metal for me in order to a
further attempt about the reflecting tube which I was the last year
inclined to by the instigation of some of our Fellows. If I do any¬
thing you may expect to hear from me. But I doubt the tool on which
they were to be ground, being in the keeping of one lately deceased
who was to have wrought the metals, is lost.

Cambridge.

Novemb. 28, 1679

Endorsed . For his ever Hon d Friend M r Robert Hook at his Lodg¬
ings in Gresham College in London. 20

This letter was read to the Royal Society at the meeting of De¬
cember 4th and aroused great interest; the members were particularly
enthusiastic about the experiment proposed to demonstrate the rota¬
tion of the earth. The minutes read:

“Mr. Hooke produced and read a letter of Mr. Newton to himself,
dated 28th November, 1679, containing his sentiments of Mons.
Mallemont’s new hypothesis of the heavens; and also suggesting an
experiment, whereby to try, whether the earth moves with a diurnal
motion or not, viz. by the falling of a body from a considerable
height, which, he alleged, must fall to the eastward of the perpen¬
dicular, if the earth moved.

“This proposal of Mr. Newton was highly approved of by the
Society; and it was desired, that it might be tried as soon as could be
with convenience.

20 An Essay on Newton’s Principia, W. W. Rouse Ball, p. 141. From the original letter
in Trinity College Library.

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227

“Sir Christopher Wren supposed, that there might be something
of this kind tried by shooting a bullet upwards at a certain angle
from the perpendicular round every way, thereby to see whether the
bullets so shot would all fall in a perfect circle round the place, where
the barrel was placed. This barrel he desired might be fixed in a
frame upon a plain foot, and that foot placed upon a true plain
every way, and the mouth of the gun be almost in the same point

over the plain, which way soever shot.

“Mr. Flamsteed hereupon alleged, that it was an observation of the
gunners, that to make a ball fall into the mouth of the piece, it must
be shot at eighty-seven degrees; and that he knew the reason thereof,
and that it agreed with his theory: and that a ball shot perpendic¬
ularly would never fall perpendicularly: and he mentioned the re¬
coiling of a perpendicular jet of waters. But this was conceived to
arise from some mistake of the gunners, in not well taking notice of
all circumstances; since a body shot perpendicularly would also
descend perpendicularly; and a body shot at eight-seven degrees
would fall considerably distant from the place where it was shot.”

It should be remembered that the Copernican theory, involving
the rotation of the earth on its axis, as well as its revolution about
the sun, was still a matter of doubt and dispute. One argument
against the earth’s rotation had been made that a body projected
vertically upwards should strike the earth to the westward of its
original position, as during the time or its flight the surface of the
earth would have moved under it to the east. The fallacy of this ob¬
jection had been shown; it is evident that the body, having originally
the same horizontal velocity as the surface of the earth, would main¬
tain this motion unaffected by its vertical flight and so would return
to the same spot from which it started, if we omit the friction of the
air. That the problem was not clearly understood is shown by the
suggestions of Wren and Flamsteed who entirely misunderstood the
fundamental principle involved in Newton’s experiment. Its value
will be appreciated by the following explanation. If a body be held
at a considerable distance above the earth’s surface, it will have the
same angular velocity as the earth; but its linear horizontal velocity
eastward will be greater than that of a point on the earth immediately
beneath it, in proportion to the ratio of their distances from the
centre of the earth. If, then, the body is allowed to fall freely it will
preserve its initial horizontal velocity, which was greater than that

21 Birch, Vol. Ill, pp. 512-513.

228

ISAAC NEWTON

of the point originally beneath it, and so strike the earth to the east
of that point. The experiment is theoretically a proof of the earth’s
rotation; but it is an exceedingly delicate one, because the distance
the body can be raised above the earth is necessarily small in com¬
parison with the earth’s radius of approximately 4000 miles; the result
is also greatly confused by the friction of the air.

At this point, Hooke’s unfortunate vanity and jealousy again
overcame his better nature. He was undoubtedly still smarting over
the victory which Newton had won in the controversy about the
nature of light. He could not help recognising the importance of
Newton’s new suggestion, but he also saw that the letter had been
hastily written and contained obvious errors. Although his reply
has been lost, we know that he bluntly pointed out these errors and
what was worse, as it broke his agreement that their mutual
criticisms should be made privately, he read his answer publicly to
the Society at the same time that he sent it to Newton. At the next
meeting on December n, it was recorded in the minutes:

Upon the mentioning of Mr. Newton’s letter, and the experiment
proposed in it, Mr. Hooke read his answer to him upon that subject,
wherein he explained what the line described by a falling body must
be supposed to be, moved circularly by the diurnal motion of the
earth, and perpendicularly by the power of gravity: and he shewed,
that it would not be a spiral line, as Mr. Newton seemed to suppose,
but an excentrical elliptoid, supposing no resistance in the medium:
but supposing a resistance, it would be an excentric ellipti-spiral,
which, after many revolutions, would rest at last in the centre: that
the fall of the heavy body would not be directly east, as Mr. Newton
supposed; but to the south-east, and more to the south than the east.
It was desired, that what was tryable in this experiment might be
done with the first opportunity.” 22

Hooke was, in the main, correct in his criticism. The ball, suppos¬
ing the earth to be pervious, would not fall in the spiral hastily drawn
by Newton, and it would fall somewhat to the south owing to the
northerly latitude of London. At the time, no one knew what the
path would be after the surface of a pervious earth was reached; and
what Hooke meant by “an excentrical elliptoid” can only be guessed
by us, and certainly had not been calculated by him. No means
could have been taken more likely to irritate Newton; he could not
endure even private correction unless offered in the most tactful

22 Birch, Vol. Ill, p. 516.

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229

way; but to correct him categorically, and in public, was simply un¬
endurable. His answer was supposed to have been destroyed, but it
has fortunately been discovered just at the present writing by M.
Pelseneer. 23 Its tone is dry and irritated in the extreme and, as he
later wrote to Halley, “I could scarce persuade myself to answer his
second letter.”

'Newton to Hoo\e
Sr

I agree with you that the body in our latitude will fall more to the
south than east if the height it falls from be anything great. And also
that if its gravity be supposed uniform it will not descend in a spiral
to the very centre but circulate with an alternate ascent and descent
made by its vis centrifuga and gravity alternately overbalancing one
another. Yet I imagine the body will not describe an ellipsoeid but
rather suit a figure as is represented [here follows a long discussion
of the probable path of the body, which shows that he had not yet
solved the general problem of attraction and would be of interest to
mathematicians only]. . . .

Your acute letter having put me upon considering thus far the
species of this curve, I might add something about its description by
points quam proxime. But the thing being of no great moment I
rather be[g] your pardon for having troubled you thus far with this
second scribble wherein if you meet with anything inept or erroneous
I hope you will pardon the former, and the latter I submit and leave
to your correction, remaining S r

Trin. Coll. Y 38

Flamsteed noted on the back of this letter. “Mr. Paget was chosen
master of the mathematical school on my recommendation: for I
found an able mathematician of him to the hospital about a month
after. And the hospital governors were so well pleased with the
choice, that, to show their gratitude, they sent me a staff, and made
me of their number the summer following.—Ebrietati deinde post
annos 7 nimium addictus immemor officii, pueros neglexit, in
Flandriam transiit, deposuit mimas, in Indiam tandem navigavit:
faxit Deus ut sanus et sobrius redeat.”

In the interval before dissipation lost him his place and drove
him as far as India, his name occurs three times in connection with
Newton. He is said to have carried Newton’s demonstration of the
law of gravitation to Halley in London, in 1684; three years later
Halley sent to him one of the few presentation copies of the Pnnctpia

88 Baily, p. 125.

244

ISAAC NEWTON

at the author’s request; and Newton mentioned that he had pointed
out a few errata in the book. Then this friend of two great men,
having acquired a certain immortality because of his contact with
them, drops out of sight. We can only echo Flamsteed’s pious wish
that God may have restored him to a wholesome and sober life.

The next five years centre about the composition of the Principia.
There can have been few, if any, instances in history of such profound
and sustained mental effort, or of such a monumental work accom¬
plished in so short a time. He left Cambridge only for brief and
infrequent intervals. Biot states that Newton was present at a meet¬
ing of the Royal Society, in London, in June, 1682, and there learned
of the accurate measurement of a degree of longitude recently ex¬
ecuted in France, by Picard. Having noted down this length, he re¬
turned home immediately and, taking up his former calculation on
the attractive force on the moon which he had made in 1665, now ob¬
tained the correct result verifying the law of gravitation. 39 It is a
matter of great importance in the history of the discovery of the law
of gravitation to know when Newton became acquainted with
Picard’s measurement, and whether he really needed to know it. The
subject must be discussed fully later, but a few words should be said
now. Biot is correct in saying it was discussed at the meeting of June
7, 1682. 40 But there is doubt in my mind whether he was then
present. His Muniment Room record shows that he left Cambridge
on May 10, but not again later in the year; unfortunately his Redit
is not given. He certainly very rarely went to London, and then for
only a few days, so that if he did go there at this time he must have
remained a full month, or else have stopped there during a course of
other visits, both of which were contrary to his habit. He was in
Cambridge on June 20 as we know by his letter to Dr. Briggs. Also,
Biot says the measurement had been made recently. The fact is, it had
been published in Paris eleven years previously, in 1671, 41 and it was
discussed several times in the Royal Society, notably in 1672. At that
time Oldenburg was supplying Newton regularly with its Trans¬
actions, and an item so important for his work would have slight
chance of escaping his attention. 42 It is certain that he attended the
meeting of May 27, 1683, for Sir Thomas Molyneux wrote that he
had been a guest then, saw Halley make some magnetical experi-

39 Biot, p. 17. 40 Birch, IV, p. 150.

41 The Biographia Britannica erroneously gives the date as 1679.

42 An exhaustive discussion of this point has been made by Professor Cajori, the results
of which will be given in Chapter IX.

LIFE IN CAMBRIDGE

245

merits, and had also the opportunity of seeing several noted men,
amongst whom was Newton. 43

There seems to be little doubt that Cambridge was lagging behind
Oxford and London in its cultivation of the new natural philosophy.
If we omit Newton, who was a solitary worker, and his friends, the
group of Platonists in Christ’s College, there was little interest ex¬
cept in the traditional learning. We can imagine that this indiffer¬
ence had been lamented by the little group who met to discuss
philosophy and science. The matter was brought to a focus by Paget,
who tried to organise a philosophical society similar to the one at
Oxford. The plan, however, fell through as the following letter ex¬
plains :

Newton to Aston

[Sir,]

The design of a philosophical meeting here Mr. Paget, when last
with us, pushed forward, and I concurred with him, and engaged
Dr. More to be of it, and others were spoke to partly by me, partly
by Mr. Charles Montague; but that, which chiefly dashed the busi¬
ness, was the want of persons willing to try experiments, he whom
we chiefly relied on refusing to concern himself in that kind: and
more what to add further on this business I know not, but only this,
that I should be very ready to concur with any persons for promot¬
ing such a design, so far as I can do it without engaging the loss of
my own time in those things.

I thank you for entering in your Register my notions about mo¬
tion. I designed them for you before now, but the examining sev¬
eral things has taken a greater part of my time than I expected, and a
great deal of it to no purpose. And now I am to go into Lincolnshire
for a month or six weeks. Afterwards I intend to finish it as soon as
I can conveniently, Etc. 44 ^ Newton ]

Cambridge, Feb. 23, 1684/5.

The letter is valuable as it shows who were Newton’s closest
friends at this time. I think we can make a shrewd guess that the
person who refused to try experiments was Newton, himself, for
who else was there in Cambridge to make them. It is fortunate that

43 Weld, Vol. I, p. 293.

44 From the copy in the Letter Book of the Royal Society (Vol. X, p. 28). The original has
not been found., (Rigaud, Essay, App. p. 24). Aston is the early friend of Newton and was
now Secretary of the Society.

ISAAC NEWTON

246

he was not induced to fritter away his time on the concerns of a
society as had been the fate of Hooke; we might have had a society,
but we should have missed far greater things. Such societies do foster
the advancement of science; they help the rank and file, but they
ruin the man of original genius who becomes engrossed in their
activities.

Work was now pressing so heavily on Newton that he wrote to
Mr. Walker, who was schoolmaster at Grantham, to engage for him
an assistant and amanuensis. A certain Humphrey Newton of that
town was recommended, and acted in that capacity from 1685 to
1690. 45 Conduitt, when he was collecting materials for a life of his
uncle, applied to the secretary for his reminiscences. We thus have
some intimate facts of Newton’s manner of living during this most
important period.

Humphrey Newton to Conduitt

Sir,—Receiving yours, I return as perfect and faithful an account
of my deceased friend’s transactions, as possibly does at this time oc¬
cur to my memory. Had I had the least thought of gratifying after
this manner Sir Isaac’s friends, I should have taken a much stricter
view of his life and actions.

In the last year of King Charles II, Sir Isaac was pleased, through
the mediation of Mr. Walker, (then schoolmaster at Grantham,) to
send for me up to Cambridge, of whom I had the opportunity, as
well as honour, to wait of [sic] for about five years. In such time he
wrote his Principia Mathematica, which stupendous work, by his
order, I copied out before it went to the press. After the printing,
Sir Isaac was pleased to send me with several of them in presents to
some of the heads of Colleges, and others of his acquaintance, some
of which (particularly Dr. Babington of Trinity) said that they
might study seven years before they understood any thing of it. His
carriage then was very meek, sedate, and humble, never seemingly
angry, of profound thought, his countenance mild, pleasant, and
comely. I cannot say I ever saw him laugh but once, which was at
that passage which Dr. Stukeley mentioned in his letter to your
honour, which put me in mind of the Ephesian philosopher, who
laughed only once in his lifetime, to see an ass eating thistles when

45 Brewster, who quotes the letter (Vol.. II, p. 90), wrongly gives these dates as 1683-
1689. H. Newton, in his letter, stated that he became secretary “in the last year of King
Charles II, and held the position for about five years.”

LIFE IN CAMBRIDGE

247

plenty of grass was by. He always kept close to his studies, very
rarely went a visiting, and had as few visitors, excepting two or three
persons, Mr. Ellis, Mr. Laughton of Trinity, and Mr. Vigani, a chem¬
ist, in whose company he took much delight and pleasure at an eve¬
ning when he came to wait upon him. I never knew him to take
any recreation or pastime either in riding out to take the air, walking,
bowling, or any other exercise whatever, thinking all hours lost that
was [sic] not spent in his studies, to which he kept so close that he
seldom left his chamber except at term time, when he read in the
schools as being Lucasianus Professor, where so few went to hear
him, and fewer that understood him, that ofttimes he did in a man¬
ner, for want of hearers, read to the walls. Foreigners he received
with a great deal of freedom, candour, and respect. When invited to
a treat, which was very seldom, he used to return it very handsomely,
and with much satisfaction to himself. So intent, so serious upon his
studies, that he ate very sparingly, nay, ofttimes he has forgot to eat
at all, so that, going into his chamber, I have found his mess un¬
touched, of which, when I have reminded him, he would reply—
‘Have I?’ and then making to the table, would eat a bit or two
standing, for I cannot say I ever saw him sit at table by himself. At
some seldom entertainments, the Masters of Colleges were chiefly
his guests. He very rarely went to bed till two or three of the clock,
sometimes not until five or six, lying about jour or five hours,
especially at spring and fall of the leaf, at which times he used to
employ about six weeks in his elaboratory, the lire scarcely going
out either night or day; he sitting up one night and I another, till he
had finished his chemical experiments, in the performances of which
he was the most accurate, strict, exact. What his aim might be I was
not able to penetrate into, but his pains, his diligence at these set
times made me think he aimed at something beyond the reach of
human art and industry. I cannot say I ever saw him drink either
wine, ale, or beer, excepting at meals, and then but very sparingly.
He very rarely went to dine in the hall, except on some public days,
and then if he has not been minded, would go very carelessly, with
shoes down at heels, stockings untied, surplice on, and his head
scarcely combed.

As for his Optics being burned, I knew nothing of it but as I had
heard from others, that accident happening before he writ his Prin -
cipia. He was very curious in his garden, which was never out of
order, in which he would at some seldom time take a short walk or

ISAAC NEWTON

248

two, not enduring to see a weed in it. On the left end of the garden
was his elaboratory, near the east end of the chapel, where he at
these set times employed himself in with a great deal of satisfaction
and delight. Nothing extraordinary, as I can remember, happened
in making his experiments; which, if there did, he was of so sedate
and even temper, that I could not in the least discover it. He very
seldom went to the chapel, that being the time he chiefly took his
repose; and, as for the afternoon, his earnest and indefatigable studies
retained him, so that he scarcely knew the house of prayer. Very
frequently, on Sundays, he went to St. Mary’s church, especially in
the forenoon. I knew nothing of the writings which your honour
sent, only that it is his own hand, I am very certain of, believing he
might write them at some leisure hours, before he set upon his more
serious and weighty matters. Sir Isaac at that time had no pupils nor
any chamber-fellow, for that, I would presume to think, would not
have been agreeable to his studies. He was only once disordered with
pains at the stomach, which confined him for some days to his bed,
which he bore with a great deal of patience and magnanimity, seem¬
ingly indifferent either to live or die. He seeing me much concerned
at his illness, bid me not trouble myself; ‘For if,’ said he, ‘I die, I shall
leave you an estate,’ which he then mentioned.

Sir, this is what I can at present recollect, hoping it may in some
measure satisfy your queries.

My wife at this time is brought to bed of a son, whom I intend to
nominate after my dear deceased friend. Would you please to hon¬
our me so far as to substitute Dr. Stukeley to stand as witness. I
should take it as a very singular favour, and would very much oblige,
Sir, your most humble and obedient servant,

Humphrey Newton. 46

Grantham, January 17, ’27/8.

Owing to the lapse of time, about forty years, he was unable to re¬
call much of any value. After a month’s delay he evidently re¬
membered other details, and their past daily life grew to be more dis¬
tinct. He consequently sent Conduitt a second letter.

Humphrey Newton to Conduitt

Sir,—I return your honour a great many thanks for the favour you
have done me in deputing Dr. Stukeley to stand in your stead as

46 Portsmouth Collection. Also quoted by Brewster, Vol. II, p. 91.

LIFE IN CAMBRIDGE

249

witness to my son. It is out of my sphere to make any grateful re¬
turn, therefore doubt not but your goodness will in that point ex¬
cuse my deficiency. I have bethought myself about Sir Isaac s life as
much as possibly I can. About 6 weeks at spring, and 6 at the
fall, the fire in the elaboratory scarcely went out, which was well
furnished with chemical materials as bodies, receivers, heads, cruci¬
bles, etc., which was [sic] made very little use of, the crucibles ex¬
cepted, in which he fused his metals; he would sometimes, tho very
seldom, look into an old mouldy book which lay in his elaboratory,

I think it was titled Agricola de Mctallis, the transmuting of metals
being his chief design, for which purpose antimony was a great
ingredient. Near his elaboratory was his garden, which was kept in
order by a gardener. I scarcely ever saw him do anything as prun¬
ing, etc., at it himself. When he has sometimes taken a turn or two,
has made a sudden stand, turn’d himself about, run up the stairs like
another Archimedes, with an evpr/fca fall to write on his desk stand¬
ing without giving himself the leisure to drew a chair to sit down on.
At some seldom times when he designed to dine in the hall, would
turn to the left hand and go out into the street, when making a stop
when he found his mistake, would hastily turn back, and then some¬
times instead of going into the hall, would return to his chamber
again. When he read in the schools he usually staid about half an
hour; when he had no auditors, he commonly returned in a 4th part
of that time or less. Mr. Laughton who was then the library keeper
of Trin. Coll, resorted much to his chamber; if he commenced Dr.
afterwards I know not. His telescope, which was at that time, as
near as I could guess, was near 5 foot long, which he placed at the
head of the stairs going down into the garden, butting towards the
east. What observations he might make I know not, but several of
his observations about comets and the planets may be found scattered
here and there in a book entitled The Elements of Astronomy, by
Dr. David Gregory. He would with great acuteness answer a ques¬
tion, but would very seldom start one. Dr. Boerhaave (I think it is),
Prof. Lpzg., in some of his writings, speaking of Sir Is.: “That man,”
says he, “comprehends as much as all mankind besides.” In his
chamber he walked so very much that you might have thought him
to be educated at Athens among the Aristotelian sect. His brick
furnaces, pro re nata, he made and altered himself without troubling
a brick-layer. He very seldom sat by the fire in his chamber except¬
ing that long frosty winter, which made him creep to it against his

250

ISAAC NEWTON

will. I can’t say I ever saw him wear a night gown, but his wearing
clothes that he put oh at night, at night do I say, yea, rather towards
the morning, he put on again at his rising. He never slept in the
daytime that I ever perceived; I believe he grudged the short time he
spent in eating and sleeping. ’A ve^ov /cal aireyov may well and truly
be said of him, he always thinking with Bishop Saunderson, temper¬
ance to be the best physic. In a morning, he seemed to be as much re¬
freshed with his few hours’ sleep as though he had taken a whole
night’s rest. He kept neither dog nor cat in his chamber, which
made well for the old woman his bedmaker, she faring much the
better for it, for in a morning she has sometimes found both dinner
and supper scarcely tasted of, which the old woman has very
pleasantly and mumpingly gone away with. As for his private pray¬
ers I can say nothing of them; I am apt to believe his intense studies
deprived him of the better part. His behaviour was mild and meek,
without anger, peevishness, or passion, so free from that, that you
might take him for a stoic. I have seen a small paste-board box in his
study set against the open window, no less as one might suppose than
a 1000 guin. in it crowded edgeways, whether this was suspicion or
carelessness I cannot say; perhaps to try the fidelity of those about
him. In winter time he was a lover of apples, and sometimes at a
night would eat a small roasted quince. His thoughts were his
books; tho’ he had a large study seldom consulted with them. When
he was about 30 years of age his grey hairs was [sic] very comely,
and his smiling countenance made him so much the more graceful.
He was very charitable, few went empty handed from him. Mr.
Pilkington, [his nephew-in-law] who lived at Market Overton,
died in a mean condition, (tho’ formerly he had a plentiful estate,)
whose widow with 5 or 6 children Sir Is. maintained several years
together. He commonly gave his poor relations, (for no family so
rich but there is some poor among them,) when they apply’d them¬
selves to him, no less than 5 guineas, as they themselves told me. He
has given the porters many a shilling not for letting him [in?] at the
gates at unreasonable hours, for that he abhorred, never knowing
him out of his chamber at such times. No way litigious, not given to
law or vexatious suits, taking patience to be the best law, and a good
conscience the best divinity. Says Seneca, somebody will demonstrate
which way comets wander, why they go so far from the rest of the
celestial bodies, how big, and what sort of bodies they are, which
had he been contemporary with Sir Is. he might have seen this

LIFE IN CAMBRIDGE

25 1

prophecy of his fulfilled by the wonder of his age. Could your Hon¬
our pick somethings out of this indigested mass worthy to be inserted
into the life of so great, so good, and so illustrious a person as Sir
Isaac Newton, it would be of infinite satisfaction to him, Sir, who is
your Honour’s most humb. and most obedient servant,

H. Newton. 47

Feb. 14,1727/8, Grantham.

While these letters are not to be despised, as they give us at least a
valuable first hand information of Newton, they are exasperatingly
disappointing. It is almost incredible that an educated man could
occupy such a position for so long and not make notes of what took
place or remember many more details of Newton’s life and habits.
He must have known, even if not till later years, that he had been in
intimate intercourse with a man whose every action would be of
interest to the world. It merely confirms Dr. Johnson’s conviction
that “Biography is rarely well executed. They only who live with a
man can write his life with any genuine exactness and discrimina¬
tion; and few people who have lived with a man know what to re¬
mark about him.” 48 It is one of the extraordinary and inexplicable
facts of Newton’s life that those who lived with him should not only
have neglected to write their memoirs or remembered his conversa¬
tion, but also have been surprised when their recollections were
desired.

The letters omit much of the information we should like to have.
The description of Newton’s appearance and character is probably
reliable. The statement of his ability to work incessantly with little
sleep or food and his absent-mindedness is undoubtedly correct. It
should be remembered, however, that the secretary knew him only
during an exceptional time. The impression is rather general that
this was his normal custom of life, but the evidence is pretty clear
that he was, on the whole, systematic and careful in his habits. We
must remember also that the work of these years broke his health,
and seems to have exhausted his creative ability. The amount of time,

47 The two letters of H. Newton are preserved in the Portsmouth Collection. I also found
an unpublished anecdote in a letter to Conduitt written by Stukeley who had been present
at the christening of the Isaac mentioned in the letters of H. Newton. “Good Sir, Last
Thursday we performed the initiation ceremony upon the young Sr Isaac Newton. The Dr.
[Humphrey Newton] gave us a very handsome entertainment and your health and your
Lady’s were frequently remembered., I gave the midwife a guinea, the chief nurse half a
guinea, and eleven shillings away among the servants.”

48 Birkbeck Hill’s edition of Boswell’s Johnson, VoL II, p. 446.

ISAAC NEWTON

252

he is said to have spent in his chemical laboratory, makes the rapidity
with which he wrote the Pnncipia even more extraordinary. It may
be that chemical work was omitted during the eighteen months he

was actually engaged in its composition.

His life was undoubtedly lonely, but he did have more associates
than are mentioned, and it is odd that Masters of Colleges should
have been such favoured guests. Of the friends mentioned, Mr. Ellis
was afterwards Master of Caius College, Mr. Laughton was a great
personal friend of Montague and was afterwards Canon of Worces¬
ter and Lichfield. Mr. Vigani was a native of Verona who drifted
to Cambridge and taught chemistry there for twenty years. In 1702,
he was made Professor of Chemistry and six years later Bentley, then
Master of Trinity, fitted up an old lumber room as an elegant chem¬
ical laboratory and attached him to his college. But the plan for a
permanent school of chemistry failed. It is of this same Vigani,
that this anecdote was told by Newtons niece, Catherine Barton, to
show her uncle’s purity of mind: “Upon Vigani’s (with whom he
was very intimate, and took pleasure in discoursing with him on
chemistry) telling him a loose story about a nun, he broke off all
acquaintance with him.” 50

Newton seems to have rivalled Lord Chesterfield in the rarity of
laughing. “When Sir Isaac once laughed, ’twas upon occasion of
asking a friend, to whom he had lent Euclid to read, what progress
he had made in that author, and how he liked him? He answered
by desiring to know what use and benefit in life that study would be
to him. Upon which Sir Isaac was very merry.” 01

Like every one else who came in contact with Newton, his secre¬
tary was especially impressed with his frequent and great generosity.
It must have been a notable trait. But we must put the open box,
with a thousand guineas, in the class of fictions or gross exaggera¬
tions. How could Newton have collected such a great sum of gold
or have carelessly left it about, when, without any subsequent in¬
crease in income, he had ten years previously been grateful for being
excused from paying the dues of the Royal Society of a shilling a
week ? To have used it for a bait “to try the fidelity of those about
him” does not consort with his frugality and business carefulness.

49 Monk’s Life of Bentley, 2d ed., Vol. I, p. 204.

50 Portsmouth Collection. It is signed C. C.—Also quoted by Brewster, Vol. II, p. 93 -

51 Portsmouth Collection. Also quoted by Brewster, Vol. II, p. 91*

CHAPTER VIII

THE MECHANISTIC HYPOTHESIS FROM DEMOCRITUS

TO NEWTON

T he history of natural philosophy from the classic period down
to the present time has been largely a development of the
mechanistic hypothesis. In essence, this hypothesis assumes
that all phenomena are due to the positions and motions of an uni¬
versal substance which has an objective existence unaffected by our
perceptions . 1 Its chief difficulty, and if I may say so its ultimate fail¬
ure, has been to find some cause which will explain how an essen¬
tially inert substance can create in the mind those manifold and com¬
plex perceptions which are received from the external world. That
is, what is the cause of motion and action, and how can they be dif¬
ferentiated into the various categories of phenomena?

However we may attempt to explain the cause of action of sub¬
stance, the fact remains that we accept, as the fundamental expres¬
sion of action, Newton’s law that all bodies mutually attract each
other with a force which varies inversely as a function of the dis¬
tances between their centres of mass. And, in accepting that as a
fact, we must give to Newton the supreme honour of creating out of
the guesses of his predecessors an almost perfect theory of mechanics.

At least to the present time, the science of mechanics most nearly
satisfies our needs for a science, in that it deals with sensible bodies
from which have been abstracted all their attributes except the
seemingly universal one of mass, or force of inertia (the vis inertiae
of Newton); and its laws, dealing as they do with only position and
motion, lend themselves readily to mathematical expression. We can,
on the basis of satisfying our desire for qualitative classification and
quantitative measurement, rate the sciences according to the degree

1 There are but few treatises on scientific subjects which do not discuss the atomic and
mechanistic hypotheses. Out of this vast literature, the following may be consulted with
profit. Whittaker, History of the /Ether, Dublin, 1910; Abel Rey, Theorie de la physique,
Paris, 1923; Hannequin, Hypothese des atomes, Paris, 1899; Stallo, Concepts of Modern
Physics, London, 1900; Karl Pearson, Grammar of Science, London, 1911; Eddington, Na¬
ture of the Physical World, Cambridge, 1929; More, Limitations of Science, New York, 1915;
lastly, that most scholarly and exhaustive Geschichte der Atomistic, 2 vols., by Lasswitz,
Leipzig, 1890.

253

254

ISAAC NEWTON

with which their laws are expressible in mechanical terms. Accord¬
ing to such a classification, subjects which consider the problems of
consciousness and mind are not sciences at all; and the biological
sciences lag far behind physics and chemistry in their ability to pre¬
dict future events with quantitative accuracy.

This does not mean that natural philosophy has advanced only
along mechanistic lines, or that all men of science have been mecha¬
nists. For example, out of many which could be cited, Aristotle in
classic, and Bergson in modern, times definitely opposed the mecha¬
nistic theory; while Plato restricted it to purely objective phenomena,
and taught that the subjective world of ideas lay entirely outside the
field of science. But I do assert that the main stream of scientific
thought has flowed in the channel formed by the conflation of obser¬
vation and mechanistic formulation.

The mechanistic method began with Leucippus and Democritus.
It was opposed by Plato and Aristotle, although they were influenced
by it. It languished during the Middle Ages; was revived at the
Renaissance; and completed by Newton. In modern times, it has
been so expanded that it is now the dominant factor in thought. The
first explicit statement of a mechanistic universe was made by Democ¬
ritus, said to be the most learned of the Greeks. In its essential ideas,
his atomic theory has persisted unchanged, but its details, as he con¬
ceived them, have become entirely negligible with the increase of
experimental knowledge.

Democritus first postulated that substance ultimately consisted of
an indefinitely large number of indivisible atoms. Thus, all bodies
differ only because of the number and relative positions and mo¬
tions of their constituent atoms. As the beginning of a reign of order¬
liness from what may be termed chaos, which is the definition of
creation, he and his disciples assumed that the atoms all had a pri¬
mordial motion towards a fixed point, the common centre of the
earth and of the universe, and that they differed amongst themselves
only in size, shape, speed, and sequence. In addition to this down¬
ward motion, they were supposed to possess a sideways slip, which
resulted in innumerable impacts between them and produced rota¬
tory motions, the cause of variety. Thus all bodies are mere chance
aggregations of atoms which in their flight come together and main¬
tain their contiguity by a fortunate provision of hook-like antennae . 2

2 In giving this short statement of the atomic theory of Democritus, I am well aware that
it is almost impossible to separate his own ideas from the interpretations and additions given

THE MECHANISTIC HYPOTHESIS

255

It was a marvelous prophecy, or guess; the modern physicist, the
chemist, the biologist, and the behaviouristic psychologist still postu¬
late the same atomic universe as did Democritus. We have vastly ex¬
tended our experimental knowledge of phenomena, but the essential
nature of substance and the cause of action is still a complete mys¬
tery. Our atom, or electron, is still but the name of a thing endowed
with all the potential properties which it is supposed to explain and,
because of our vastly increased knowledge, the inadequacy of the
electron is more apparent to us than the atom of Democritus was to
the Greeks. As Professor Armstrong caustically remarked, “we are
told that the electron does everything but how it does anything we
are not informed.”

Reduced to its simplest terms, the atomic theory, as interpreted by
the Epicureans, is the expression of the laws of probability of chance
impacts. But, the absolute denial of purpose, or design, in the laws
of nature is so repugnant to the mind that even its founder, whose
name is a synonym for materialism and necessity, can hardly be called
a pure mechanist since there are indications that he gave his atoms
a tendency, or purpose, to move. At least, when he declared that the
souls of men were but atoms of a finer size and of a more nimble
motion, he either denied the attribute of will and purpose to the soul,
or else endowed its atoms with the power of choice. And his disciple,
Empedocles, certainly maintained the principle of choice, under^the
terms of love and hate, as guiding the creation of living beings.

It was because of their search for a principle of design that the
two greatest Greek thinkers, Plato and Aristotle, opposed the ideas
of Democritus. The much heralded opposition of the Church to
science, during the Middle Ages, was limited to the interdict of the
teaching, and belief in, the atomic theory and a mechanistic universe.
And the age-long conflict between science and religion narrows down

to it by his disciples, the Stoics and Epicureans. It is likely Democritus supposed his atoms
to move in all directions and that the uniformly downward motion, the sideways slip, and

the hook-like antennae, were later modifications. . . .

3 The atomic theory of Democritus has been generally characterised as synonymous with
mechanistic materialism and fortuitous chance. It is well to point out that Professor Hack
(God in Greek Philosophy, Princeton Press, 193O takes an opposing view: The tact that
Leucippus and Democritus are habitually called ‘Atomists’ is responsible for the dense cloud
of misunderstanding that has enveloped their doctrine” (p. 128). This false conception e
lays at the door of Aristotle, who “attributed to other philosophers opinions which are ob¬
vious fabrications of his own.” According to Professor Hack Democritus believed there
were, in addition to inert material atoms, also an “infinite number of indivisible Beings that
possessed Spherical Form with Mind, Psyche, Fire, and God” (p. 133)- He quotes passages
from the classical commentators to prove that these spherical atoms animate even stones, and

direct otherwise chance motions.

ISAAC NEWTON

256

to the same question. There can be no doubt that the logical con¬
clusion of this hypothesis is a denial of every form of free will; and
in that sense it is atheistic. Even today there are few, and one may
almost venture to say no, men of science who are willing to live in the
unbreathable atmosphere of such a stultifying philosophy. In their
studies and laboratories, they may theoretically subscribe to, and
search for, rigorous and mechanical laws of nature, but their daily
lives and actions are based on the conviction of free will and purpose.

Although Plato was singularly indifferent to experimental science,
and has contributed little or nothing to its body of knowledge, he
nevertheless in the Timaeus* grasped one of the fundamental prin¬
ciples of the scientific method and pointed out its inherent limita¬
tions. According to his philosophy, the world was created according
to a plan or design by the Demiurgos or Worldbuilder; and man,
being endowed with an innate knowledge of this plan, can by the
right sort of education penetrate more and more deeply into a just
knowledge of the Creator’s design and laws. There are thus two
realms, the real world of the mind and the apparent world of objec¬
tive phenomena. Since our contact with the phenomenal world
comes to us only through our fallible sensations the best information
we can obtain of objects is limited to an opinion, or conjecture, which
cannot be based on conviction, or strengthened by judgement. For
example, our own observations can never be exact, nor can we be
certain that our impressions closely correspond with those of others;
our picture of the external world is a mere seeming one which must
be modified to conform to the real, or mental, world of ideas based on
the divine laws. A simple illustration will show how essentially true
is this definition of the scientific method. If there be a fundamental
law of science, it is that substance is conservative. Without such a
conviction there is no more stability in the world than in the tricks
of legerdemain where rabbits pop out of a hat. If one enquires of
the average student what is the proof of this law the answer will in¬
variably be that if one weighs a candle, enclosed in a box, before and
after burning it, the weights will be the same. In brief, the claim is
made that the law is not a matter of faith in the orderliness of nature

4 There must always remain a doubt whether Plato is giving his own ideas in the Timaeus,
or whether he is, for the most part, interpreting the philosophy of the Pythagoreans as it was
understood by an educated Athenian. The appearance of Socrates in a minor role lends sup¬
port to the belief that he did not regard the essay as an integral part of his own philosophic
system. This point of view is taken by A. E. Taylor in his Commentary on Plato’s Timaeus,
Oxford, 1928.

THE MECHANISTIC HYPOTHESIS 257

and of the reliability of reason, but an induction drawn from experi¬
mental evidence. One might retort that there is some faith necessary
in the assumption that matter in a star, for example Betelgueuse, is
identical with that on the earth; it must be admitted that our experi¬
mental evidence derived from weighing objects in Betelgueuse is
slight. But we need not go so far afield to show that the general and
fundamental laws of science are not formulated from the data of
experience; on the contrary, our experimental data are revised and
changed to conform to preconceived deductive laws. If one weighs
any object ten times there will certainly be ten different numerical
results, if the balance be sufficiently delicate and the experiments be
done with care; and the greater the accuracy of the experimenter, the
greater will be the differences of his readings. Or, if ten persons
weigh the same object, the chances are that there will be ten different
results, and the certainty is that they will not all agree. Which of
these is the true weight, we have no means of knowing. We are
driven to the dilemma of either assuming that the object has one
real weight which we can obtain only approximately by taking the
average of all the trials, 5 or else that it has simultaneously as many
weights as there are observations; we adopt the former as the truth
and tacitly admit that our opinions of the objective world must in
all cases be altered to conform to preconceived subjective ideas. Let
us give another illustration which does not involve measurement.
The retinas of a few eyes are insensible to a difference of colour be¬
tween the leaves and blossoms of a geranium. There are no objective
experiments which can make these so-called red colour blind persons
aware of a colour difference of sensation. As it happens, they form
a small minority, and they submit to the opinion of the numerical
majority that their eye-sight is defective, but their subjective convic¬
tion must still remain unchanged. If the contrary happened to be
the case, and only rare individuals could perceive a distinction of
colour between such leaves and blossoms, does any one doubt that
their objective opinions would be changed to agree with the opinion
of the majority? As Plato held, since objective things and their phe¬
nomena can be recognised only by observation, the most that we can
derive from them is an opinion, based on belief and conjecture, and
modern science follows Plato in so far that it attempts to portray not
a real world but an interpretation of observed phenomena as a logi-

5 The mathematical law of probability and chance, which governs all experimental work,
is based on the axiom that errors of observation disappear only with an infinite number of

trials.

ISAAC NEWTON

258

cal system in conformity with our mental ideas. And both Plato
and modern science agree that the laws of the objective world can be
expressed fully only in mathematics.

So far as the physical world is concerned, Plato accepted an atomic
theory in which the original Democritean atom was replaced by the
four elementary substances introduced by Empedocles,—earth and
fire which provide us with tangibility and visibility, and water and
air which are symbolically linked to the other two by a mathematical
law of mean proportion. However, these substances are but names
for elementary geometrical solids built up from triangles and squares,
—the cube, the tetrahedron, the octahedron, and the icosahedron.
Although Plato added nothing to experimental science, yet his clearly
expressed doctrine, that to the determination of things by mathe¬
matical formulae is linked at the same time their reality and their
perceptibility, was an undying service to science. Unfortunately, the
neo-Platonists, instead of developing this fruitful idea, turned rather
to the mysticism of the Timaeus\ and science, till the Renaissance,
looked to Aristotle as its guide.

In estimating the influence of Aristotle on science, it must be re¬
membered that he was an almost unquestioned dictator of scientific
opinion during the Middle Ages, and that he was opposed to the
atomic and mechanistic theories. He was by temperament a biolo¬
gist, indifferent to experimental physics, and suspicious of mathe¬
matical logic. Our discussion of his influence must be here limited
to his ideas on physics in general, and on the mechanistic theory in
particular. As a biologist we may well leave the estimate of hE genius
to the greatest of all naturalists, Darwin, who at the end of his life
wrote to Dr. Ogle to acknowledge his translation of Aristotle’s De
Partibus Animcdium: “From quotations which I had seen, I had a
high notion of Aristotle’s merits, but I had not the most remote no¬
tion what a wonderful man he was. Linnaeus and Cuvier have been
my two gods, though in very different ways, but they were mere
schoolboys to old Aristotle .” 6 But when we consider his influence as
a physicist, it is more than probable that, on the whole, it was harm¬
ful in its effect on later thinkers. He has to his credit no body of ex¬
perimental discoveries in physics, as he had in biology, nor does he
seem to have thought them necessary. He discarded the atomic
theory and mathematical formulation of quantitative measurement,
and substituted a set of preconceived metaphysical principles deeply

6 Life of Darwin, by Francis Darwin, Vol. II, p. 427. Appleton, 1887.

THE MECHANISTIC HYPOTHESIS

259

tinged with animism, such as: nature abhors a vacuum; matter see\s
its own kind . 7

When considering the natural philosophy of Aristotle, we should
not forget that in the essential belief in the reality of the ideal uni¬
verse he agreed with Plato. Both also regarded the universe as a
manifestation of design and purpose; but Aristotle made a less dis¬
tinction between the designer and the designed. While he also
agreed with his teacher in postulating the existence of elementary
substantial bodies, he accused Plato of assuming those elements to
be mere geometric forms.

The discussion of Aristotle’s scientific ideas is made more difficult
because they are scattered in several books. Apparently, he pursued
two main lines of thought, which are irreconcilable with each other:
in the one, he viewed the universe as variations of substance; and, in
the other, as a dynamic manifestation of motion. He seems to have
foreseen the present cleavage between those physicists who start from
the material atom, and those who build on atoms of energy.

In his first scheme, Aristotle identified substance with space, as
did later Descartes, and for the same reason, since they both denied
the possibility of a vacuum. The essential element of a material body
is form, but the existence of bodies does not result from an act of
creation out of nothing, rather it is the passage from a potentiality
(dynamis) of substance to become form. This conception of poten¬
tiality is, perhaps, his greatest contribution to science. By it, the
physicist accounts for the beginning of the downward motion of a
body which has been raised to a height, and it is the essential idea
in the laws of the conservation of energy, and of matter. Aristotle
also accepted the four elementary forms of earth, water, air, and fire;
but these were not fixed and could be changed one into another by
the active agents of heat and cold, moisture and dryness. As he was
a dualist, he made a definite break between the living and the inani¬
mate worlds. To provide for life and the soul (psyche), he added a
fifth, or quintessence. As matter is the form of physical bodies, so

7 My use of the word metaphysical, in this sense, is frequently criticised as if I attributed
to metaphysics only crude guesses. This is not at all my idea, but I know no other word to
express a fundamental difference between the physical method of deduction from objective
experimentation, and what I designate as metaphysical deduction from subjective experience.
For example, the study of light is a physical problem and ends with the absorption of the
light energy by the retina; whereas, the study of sight, I term metaphysical, as it involves
sense perception and mental interpretation. Perhaps, the term psychological could be used,
but psychology is generally defined as an objective and scientific study of the sensations and
of the mind; and I wish to distinguish between the mental interpretation of material phe¬
nomena, and of sense perceptions.

260

ISAAC NEWTON

the soul is the form of living bodies. In the plant world, the soul is
limited to generative and nutritive functions; in animals, the appeti¬
tive function is added; in man, alone, there is also the rational soul.

Although Aristotle remained true to the Platonic philosophy of
ideal universals and viewed the universe as the result of design, yet
he was so essentially a scientist by temperament that he failed to dis¬
tinguish sharply between the Designer and the designed. As the
modern scientist substitutes Nature, or natural law, for God, so he
constantly sought for a mechanistic scheme for the objective world;
thus, he proposed motion, or change, as the efficient cause of phe¬
nomena. While he classified change in four categories,—spatial,
qualitative, quantitative, and temporal,—all changes are dependent
on motion in space. So far his mechanistic world of material ele¬
ments, motion, and energy, is truly modern, since, for example,
physicists explain light, heat, etc., as mechanical motion, and many
biologists attribute life to the same cause. But, when he attempted
to connect his active cause, mechanical energy, with his final cause,
the Designer, he was forced to introduce the principle of animism
and floundered in a morass of inconsistency.

In his mechanistic scheme, Aristotle assumed that the heavens are
pure, celestial substance, the quintessence, and that, since the circle is
the only invariable curve, they of necessity eternally revolve in that
path. He, first, placed the stars in one outermost shell which re¬
volves daily about the stationary earth as a fixed centre. This shell
is the Primum Mobile whose perpetual rotation is the cause of all
other motions. Next, each planet is attached to a concentric shell
whose radius corresponds with its distance from the earth. The
rotary motion of these secondary shells is caused by having their
polar axes embedded in the substance of the circumjacent shell. That
of the moon, being nearest to the earth, is the least in diameter; and
all told, there are fifty-five of these shells.

Aristotle’s first insuperable difficulty was to account for the motion
of the Primum Mobile. This, he accomplished by making God the
final cause of motion; for this purpose he was designated the Prime
Mover, or the Unmoved Mover; and, by direct linkage, produces the
rotation of the Primum Mobile and thus, indirectly, of all the other
spheres. If we ask, how can that, which is itself unmovable, cause
motion ? The answer was, by love and desire. And if we again ask,
how can love be a cause of motion? We find that Aristotle aban¬
doned the mechanistic hypothesis and endowed the Primum Mobile

THE MECHANISTIC HYPOTHESIS

261

with soul; and the heavenly bodies are living being. As they are
necessarily perfect, they desire a life as like the everlasting and un¬
changing spiritual existence of the Unmoved Mover as possible. Since
they cannot copy that love in kind, their desire causes them perpetu¬
ally to move in circles, as the best possible substitute. Aristotle, thus,
introduced an unfortunate connection between physical motion and
moral principles which was to plague thought for centuries; just as
the biological evolutionists of the nineteenth century are plaguing us
by their unfortunate phrase of an evolution from lower to higher
forms, and thus gave a moral significance to mere structural varia¬
tions. Our theologians have discarded the association between mo¬
tion and morals, but they still connect morals and muscles.

It has been shown that Aristotle accepted the fundamental pos¬
tulates of the mechanistic hypothesis, and could escape its conclu¬
sions only by introducing the principle of animism. A discussion of
the false system of science which the Schoolmen built on his dicta
may be omitted; but two permanent contributions, which he gave to
the scientific method, should be emphasized.

One of these contributions, the idea of potential, has already been
mentioned. The other is Aristotle’s discovery that science is not
concerned with the problem of creation, or the beginning of sub¬
stance, since natural law, to have any value, must be continuous and
invariable. In conformity with this principle of law, the physicist
assumes as an axiom that the nature of his substance, matter, and the
laws of force and motion, have always been in the past what they are
now, and what they will always be in the future. The confusion,
which arises when the contrary is admitted, can be seen in the
predicament of biology and psychology.

The biologists, following their acceptance of the evolution of
species, have unfortunately assumed: because the earth may, at a past
time, have been unfit for the existence of living bodies, therefore life
itself was then non-existent. They are thus forced into the unscien¬
tific position that life, which is the biological substance, and the laws
of life, were either a special creation or were evolved from mechanical
matter and laws at some finite time in the past. If biological law
were discontinuous in the past, then there is no certainty of its con¬
tinuity in the future; or, if life and its laws are mere evolution of mat¬
ter and its laws, then there is no science of biology built on the axiom
that life proceeds only from life (ovurp ab ovo). The case of psychol¬
ogy is still worse for it accepts a more recent time for the appearance

262 ISAAC NEWTON

of the self-conscious mind. And these two sciences will remain in the
same unscientific condition in which they are at present, till they
adopt the Aristotelian concept that substance is timeless and mani¬
fests itself in the three irreconcilable categories of matter, life, and
spirit. The truth of this concept is confirmed by mathematics which
has proved that the laws of matter are functions of time and space;
the laws of life are not a function of space; and the laws of spirit are
a function of neither time nor space.

With the collapse of the Greek and Roman civilisation, the philos¬
ophy of Plato and Aristotle was practically lost and their works
were seldom read. Knowledge of Aristotelian physics was revived
by the Syrian Christians 8 who translated his medical writings into
Syriac. His works were first translated from Syriac into Arabic dur¬
ing the caliphate of Almamun (813-833). By the tenth century, his
philosophy had become widely known, and its dominating authority
was fixed by the two great Arabian commentators, Avicenna and
Averrhoes. The western world, however, did not acquire access to
his scientific writings until the latter half of the twelfth century
when they and the commentaries of Avicenna, Averrhoes, and other
Arabian philosophers, were translated first into Castilian and then
into Latin under the direction of Archbishop Raymond of Toledo.

The rise to power of the monastic orders and the religious awaken¬
ing of the twelfth and thirteenth centuries were hostile to the spread
of natural philosophy on the ground that it diverted the attention
from the spiritual life and, founded as it was on natural law, it sub¬
stituted a mechanical world for the divinely revealed plan of God.
There were sporadic attempts to forbid the teaching of natural
philosophy until Gregory IX, in 1231, lifted the ban against the study
of physics except for those writings which could be proved to be
heretical in influence; and in 1254 the physics and metaphysics of
Aristotle were officially listed in the curriculum of the University of
Paris. This change of sentiment was due mainly to the influence of
Albertus Magnus and Thomas Aquinas. On the one hand, as the
greatest of mediaeval commentators of Aristotle, and on the other, as
the authors of the orthodox Catholic faith, they so fused Aristotelian
philosophy and Christian ethics that the authority of the one over
observation and reason became as absolute and dogmatic as the other
over matters of faith.

For three centuries, the opinions of Aristotle, as interpreted by his

8 Lasswitz, Geschichte der Atomistic, Vol. I, p. 85.

THE MECHANISTIC HYPOTHESIS

263

commentators, were the touchstone of truth; the direct evidence of
experience and the deductions of the reason were confirmed, or
denied, according as they agreed with his metaphysical scheme of
nature. With both secular and sacred teaching entrusted to the mo¬
nastic orders, the Church and the University submitted to the crush¬
ing weight of his authority. While it would be unjust to hold
Aristotle accountable for the neglect of the sciences during the Mid¬
dle Ages, since that was the result of the desperate need to rebuild a
new social order, yet it is equally true that his philosophy led what
little science there was by a false path into a barren and sterile field.
It was most significant that the Renaissance of literature and art was
heralded by a revival of Platonism, and that the later Renaissance of
science was a determined and bitter revolt against Aristotelianism.
It has commonly, and erroneously, been assumed by most historians
of science that this revolt was directed against the Church but that
was not the case; the opposition by the Church was for the most
part forced upon it by the pressure of the teaching monastic orders,
and especially of the Jesuits, who when attacked on account of their
false doctrines of physical facts countered with the charge of heresy.
The fault lay rather in the policy of confiding to the same persons
the direction of both secular and religious instruction.

This opinion is confirmed by the great leaders of the new learning.
It is noteworthy that Copernicus, Kepler, Pascal, and Newton were
zealous defenders of the doctrines of their churches, and believed
their scientific work to be a powerful support to the Christian re¬
ligion. Of the others, Bacon, Galileo, and Descartes were at least
orthodox in their public expressions of faith, and submitted to the
authority of the churches in religious matters. In the published
writings of all of them, whether zealous or luke-warm, I have found
no trace of any hostility to the doctrines or authority of their
churches, but I have found frequent and explicit statements that they
were determined to break the dogmatism of the Aristotelian science.

This dogmatic and false science did not have its source in the
particular beliefs of Aristotle, but resulted from the fact that his
earliest commentators infused their own oriental mysticism with the
metaphysical tendencies of the Greeks. In natural science Aristotle,
himself, and his successor, Theophrastus, had founded a real school
of the biological sciences which was smothered. Instead of develop¬
ing it into an objective scientific method, his doctrine of the transmu¬
tation of the elements became the basis of mediaeval alchemy with its

ISAAC NEWTON

264

fantastic mixture of sense and nonsense, and its supposed origin in
the esoteric formulae of the mythical Trismegistus. Still more fatal
to the progress of the physical sciences were the tenets of a celestial
matter which exerted a direct influence on physical phenomena and
on life; of natural motions which were significant of moral at¬
tributes; and of the vitalistic conception that nature acted with pur¬
pose to avoid a vacuum, and to cause the elements to seek their
natural levels. The mathematical school which flourished in Alex¬
andria would certainly have developed into a modern science if it
had been continued. The works of its five greatest leaders, Euclid
(C. 300, B. C.) and Apollonius (C. 247, B. C.) in geometry, Archi¬
medes (287-212, B. C.) in mechanics, Eratosthenes (C. 276, B. C.) in
mathematics, and Hipparchus (C. 160, B. C.) in astronomy, can still
be read with profit, and Copernicus closed the gap of eighteen cen¬
turies when he again picked up the lost thread of the Platonic philos¬
ophy of science. Science, with the rest of Greek culture, was lost in
the collapse of classical civilisation and, when it was revived by the
Arabians who had inherited the astrological beliefs of the Chaldeans,
it started on its unfortunate career of alchemy and astrology. It is
easy to see how those subjects acquired their fascination and power.
In the Middle Ages, men saw the constant and immediate interposi¬
tion of God in every act of their lives and, in the distracted and
ominous state of society, feared that He had delivered the world into
the power of the Devil and his satellites. It is not surprising, there¬
fore, that they invoked the magic and prophetic arts of the astrologer
and alchemist in order to get a glimpse of the future. Under the
stress of so great a temptation to profit from the cupidity, the ambi¬
tion, and the fear of their unlearned patrons, “the great pretenders
of the Hermetic arts” developed that strange mixture of science and
chicane, of serious purpose and venal deception.

In spite of its many defects, astrology kept alive an interest in
science. In order to draw up satisfactory horoscopes, its votaries spent
their nights in observing the planets and stars; and to locate their
positions, a great variety of apparatus was constructed which far
exceeded all other instruments in accuracy. Nor can we doubt that
aggregations of stars served as a visible and magnified illustration of
the atomic theory of matter. The unquestioned authority of astrology
was the Syntaxis of Ptolemy, or Almagest as it was named by the
Arabs. Although the writings of Hipparchus are lost, we are cer¬
tain that he was the author of most of the observations, of the calcula-

THE MECHANISTIC HYPOTHESIS

265

tions, and of the catalogue, of the stars found in the Almagest. But,
the study of the planets which enabled Ptolemy to evolve his cele¬
brated cosmic system is his own work. However cumbersome this
system with its epicycles on epicycles later became, it is the natural
description of the motions and paths of the planets, satellites, and
sun, as observed by a person stationed on the earth. It is superior to
the heliocentric system so far as the apparent paths of the three most
important bodies,—the earth, the sun, and the moon,—are concerned;
it is inferior, in that the motions of the other planets and their sat¬
ellites become complicated epicyclic curves. It must not be over¬
looked that the observed map of the heavens is still drawn with the
earth as the centre and is then remade, on the basis that the sun is the
fixed centre, because the calculation of the orbits is thus simplified.
It is true, in a sense, that the heliocentric system is a mathematical
device invented to reduce the labour of computation. There is, how¬
ever, another cause which forced the abandonment of the Ptolemaic
system on absolute grounds; if the earth be at rest, then the fixed
stars, because of their enormous distances from it, must daily travel
about the earth from east to west at simply incredible speeds; if, how¬
ever, the earth revolves on its axis in the opposite direction the same
result is accomplished with a reasonable velocity. The rotation of
the earth is now so well established by direct evidence that there can
be no question of fact as to which is the real system. Thus, the de¬
ciding factor in establishing the heliocentric system was the daily
motion of the earth and not its annual revolution about the sun. The
early enthusiasts for the Copernican system failed to give Ptolemy
just appreciation; they overlooked the fact that their own system,
while it reduced the labour of computation, did not discard the use
of epicyclic paths, but merely reduced their number.

Our deepest admiration should be given to the long line of as¬
tronomers and astrologers before the Renaissance. It is little short of
marvellous that they should have recorded such a mass of observa¬
tions, have attained such precision of measurement without the aid
of telescopes and clocks, and have performed their computations
without the devices of modern mathematics. We may omit the
specific record of their own achievements in elucidating the problems
of astronomy, and merely mention what they accumulated for the
use of their successors.

Hipparchus, besides his many contributions to a correct discussion
of the perturbations of the solar system and the magnitudes involved,

266

ISAAC NEWTON

drew up a catalogue of the positions of 1028 fixed stars. Ptolemy
made this catalogue accessible by incorporating it in the Almagest,
and he also published his own tables of the motions of the planets
which gave their positions correctly with an accuracy of a quarter of
a degree. In the tenth century Albategnius corrected and enlarged
the catalogue. Two centuries later Alphonso X, king of Castile, ex¬
pressed his royal irritation because of the unnecessary complications
introduced by God in His plan of the universe and, as he was unable
to substitute his own ideas, he gathered together the most celebrated
Arabian, Jewish, and Christian astronomers and set them to the task
of describing more exactly the existing cosmic system. The result of
their deliberations was the famous Alphonsine Tables which ap¬
peared in manuscript in 1252, but were not published at Venice until
1483. These tables, with one prepared by the Tartar prince, Ulugh-
Beg provided the data for the beginning of modern astronomy and

science.

By the middle of the fifteenth century, the Renaissance was in full
flower so far as art, literature, and philosophy were concerned, but
the new spirit of science had begun to show itself only by a certain
restlessness and by a timid questioning of the dogmatic scheme of
nature which had evolved from the Judaic cosmogony and the
Aristotelian philosophy; the impetus to this restlessness had un¬
doubtedly come with the revival of Platonism which followed the
enthusiastic reception by the Italians of the Greek scholars who had
fled from the destruction of Constantinople. With Platonic philos¬
ophy, came also a renewed interest in mathematics and mechanics.
The individualism which had become so dominant in art, literature,
and national life, finally penetrated religion and science, and brought
about the substitution of personal responsibility both towards God
and nature for the authority of divine revelation through the
Church.

It is significant that the three proponents of this new attitude,
Erasmus, Copernicus, and Luther, should have been almost exact
contemporaries. And from their lives can be dated the struggle be¬
tween religion and science which has since then been followed by
a steady decline in the religious spirit, and by an equal growth of the
scientific attitude of dependence on observation and reason. It
would be difficult to say which of the two, Luther or Copernicus,
was the more responsible for our present individualistic sectarianism
and philosophic disintegration. As modern Protestantism must look

THE MECHANISTIC HYPOTHESIS 267

to Luther for its creator so modern science is to be dated from the
work of Copernicus.

Nicolaus Copernicus, or Koppernigk, was born at Thorn on the
border between Prussia and Poland in 1473, and died in Frauenburg
in 1543. He first studied at Cracow and then went, as did all the
eager youth, to Italy to drink in the new knowledge. This first stay
was passed at Bologna and Padua, where he became proficient in
mathematics; it was followed by a year at Rome, in 1500, as profes¬
sor of that subject. After a short visit at home, he again returned the
following year to Italy and, with the versatility then so common, he
studied law and medicine at Padua and was made doctor of laws, in
1503, by the University of Ferrara. His education completed, an ac¬
complished mathematician and an enthusiastic astronomer, he settled
in Frauenburg for the remainder of his life. His uncle, the bishop,
appointed him a canon of the cathedral, and here he peacefully car¬
ried on a busy life in the church and in an observatory which he
built for himself. Of a noble family, protected by the powerful in¬
fluence of his uncle, well read in Greek and Latin, and distinguished
in the sciences, he meditated on the insufficiency of the Ptolemaic
cosmic system until he finally evolved his own planetary scheme.
He tells us that he first began his great work in 1506 and pursued it
with such deliberation and patience that the work was not com¬
pleted until 1530. And even then, he laid it aside for thirteen more
years and only published his results after his reluctance had been
overborne by the entreaties of his friends. As he lay on his death-bed,
his great masterpiece De revolutionibus corporum codestium was
placed in his nerveless hands. His reasons for this long delay are
given in his preface: “I believe that as soon as it is known what I
have written in this work on the motions of the earth, a great hue
and cry will be raised against me. Besides I am not so enamoured
with my ideas as not to pay attention to what others will think of
them; then, too, although the thoughts of a philosopher are far re¬
moved from the opinions of the vulgar, because he has set himself
to seek the truth, so far as God permits to human reason, I am not
disposed to reject entirely the opinions thus opposed to me. All these
motives, as well as the fear of becoming, because of the novelty and
the apparent absurdity, an object of derision, have made me almost
renounce the project. But my friends, amongst them Cardinal
Schomberg and Tidemann Gisius, bishop of Culm, have overborne
my reluctance. The latter, above all others, has most insisted that

268

ISAAC NEWTON

I publish this book, which I have meanwhile kept on the stocks not
only nine years, but almost four times nine years.”

In any astronomical system the determination of the paths of the
stars is a problem of relative motion. Now, if one considers the rela¬
tive positions of two moving bodies, the result is evidently the same
whether one assumes both to move with respect to some other fixed
point of reference, or whether one supposes either one of the bodies
to be at rest and the other to perform all the motion. Thus, an ob¬
server of the stars will obtain a correct diagram of their successive
positions if he plots his observations with reference to himself and the
earth as a fixed point. It is in fact the only way actual observations
can be made, and it is followed by astronomers today. It is thus a
monument to the genius of Hipparchus, and his successor Ptolemy,
that from their observations astronomers developed the well-known
Ptolemaic system. Briefly, in that system, the earth was assumed to
be at rest; the sun, moon, and fixed stars will then appear to revolve
about it in circles, while the then five known planets describe cyclic
paths which are traced out by a point on a circle rolling on another
circle. Knowing the position of a planet at several points, in its
orbit, its future path could be calculated from the properties of the
curve. The difficulty of the system lies in the fact that such calcula¬
tions are laborious because of the nature of these cycloidal curves;
furthermore, every perturbation of an orbit must be accounted for by
supposing a secondary epicyle until, by the time of Copernicus, the
system had become embarrassingly complex.

Copernicus, early in his life, became convinced that this compli¬
cated system was contrary to the prevalent belief that the order of
nature was symmetrical and simple, and that there must be some
conceivable system which would be consonant with that belief. The
orbits of the sun and moon agreed with the Aristotelian philosophy
of the circle as the necessary and perfect celestial motion, but the
paths of the planets were anything but simple and symmetrical;
could not there be devised a system, he argued, which would bring
them into a law of harmony? Another puzzle, in his mind, was the
assumption that the fixed stars made a daily revolution about the
earth. In the opinion of the classical philosophers, the universe was a
small and rather intimate system. The moon, sun, and planets were
each located in a solid spherical shell which rolled it about the earth,
as a fixed centre, in its diurnal revolution. Just outside these was the

THE MECHANISTIC HYPOTEIESIS

269

shell which carried all the stars and thus their speed of rotation
presented no special difficulty. But, as knowledge increased, astron¬
omers began to locate the stars at increasingly greater distances from
the earth till, at the beginning of the sixteenth century, the conse¬
quent speed of their motion had become an embarrassing problem.

In this state of doubtful groping he, being a student of Greek,
turned, as was the custom of the day, to the classic philosophers for
enlightenment. To his surprise and delight, he tells us Plutarch 9
mentioned that some of the Pythagoreans, and notably Philolaus,
believed the earth to be a sphere which rotated daily on an axis, and
revolved annually about the sun as a fixed centre. He also found on
the authority of Martianus Capella that other philosophers supposed
Mercury and Venus to revolve about the sun, and not about the earth
as a centre. Copernicus seems to have grasped almost immediately
the solution of the problem. He had merely to imagine himself ob¬
serving from the sun as a fixed centre, and he would see the earth
and the other five planets revolving about him in circles, thus
avoiding the epicyclic curves observed from the earth. When he
wished to calculate the path of the moon as a circle he had merely to
transport himself back to the earth. Also, by supposing the earth to
rotate on its axis the diurnal revolution of the sun and stars was made
unnecessary. To grasp the general idea was one thing, but to sup¬
port the idea by convincing proofs was a different matter, and he
spent thirty years at the task before he felt that he had satisfactorily
solved the problem.

Copernicus was shrewd enough to realise that his theory would
meet with determined opposition and would need the most con¬
vincing proof before it would be accepted. The Ptolemaic system
had the authority of centuries behind it, and the public would cer¬
tainly shudder with terror at the thought of the solid earth whirl¬
ing and speeding through empty space. More dangerous still might

9 The passages discovered by Copernicus are probably as follows:

“Philolaus, the Pythagorean, believes that the earth moves in a circle about the fire,
obliquely, in the same fashion as the sun and moon.”

“Heraclides of Pontas and Ecphantus, the Pythagorean, make the earth move, not however
in the movement of translation but in a revolving movement, like a wheel on its axle re¬
volving about its own centre from the west to the east.”

It appears that Copernicus must have confused the statement made concerning the views
of Ecphantus in the second paragraph with the statement in the first paragraph by Philolaus.
The passages are found in the Collection of Opinions Adopted by the Philosophers which
was attributed to Plutarch and appears in the Moralia, but is now attributed to Aetius.
Cf. Diels, Doxographi Graeci, p. 378.

270

ISAAC NEWTON

be the opposition of the Church which would certainly regard as
heterodox, and probably as blasphemous, any dislocation of the earth
from its central and fixed position ; even more obstinate would be the
hostility of the Aristotelian philosophers who could not fail to see
that such a conception of the universe meant the downfall of all the
laborious structure they had erected. Copernicus could only hope
that time would reconcile the people to his ideas; to ward off the op¬
position of the clergy, he dedicated his book to the Pope, Paul III, a
man of great learning, who accepted the honour and permitted it to
be published and circulated.

With the founding of the Society of Jesus in 1534 and its sanction
by Paul six years later, began the great struggle between the Jesuits
and the Dominicans for control over the educational system. The
growth of the Jesuits had been phenomenally rapid, and into their
hands had fallen the direction of the Counter-Reformation which at¬
tempted not only to suppress Protestantism but also to set the Church
against the new science as heretical and contrary to the authoritative
teaching of Aristotle. In spite of their opposition, the Copernican
system steadily gained the adherence of astronomers and scholars.
It was not until 1616 that the Jesuits were able, in the pontificate of
Paul V, to place the book in the Index as heretical; and even after
that it was tacitly permitted to circulate and to be read. As Kepler
sadly remarked, the Copernican system had quietly spread its in¬
fluence unmolested for eighty years till Galileo forced the issue by the
publication, in 1632, of his Dicdogo del due massimi sistemi.

Important as was the work of Copernicus, he cannot be said to
have established his cosmic theory. For that a mass of accurate data
on the positions of the planets was needed, and he was not such an
observer; indeed he could not be because of the crudeness of the in¬
struments at his command. For this data, we are indebted to the
prince of astronomical observers, Tycho Brahe. Aided by the munifi¬
cent patronage of Ferdinand II, King of Denmark, he was able to
build a sumptuous observatory on the island of Hven and to install
there such a set of instruments as had never before been placed at the
service of an astronomer; indeed, they could be superseded only by
the invention of the telescope. In this observatory, and later at
Prague where he secured the support of the Emperor Rudolph II,
he made such accurate determinations of the positions of the stars
and of the orbits of the planets, which later were embodied in the
Rudolphine Tables, that he put into the hands of his assistant and

THE MECHANISTIC HYPOTHESIS

271

successor, Johann Kepler, the material he used to develop the laws of
the heliocentric system, and to remove all doubts as to its truth.

Kepler was one of the noblest and most extraordinary figures in
the history of science and, at the same time one of the most op¬
portune, since his rare combination of mysticism and passion for facts
made him an ideal figure in the transition period between the
mediaeval and modern conceptions of science. Born, 1571, in Weil in
Wiirtemberg, he began life as an assistant in his father’s inn. Sickly
and frail in health, he was exposed to such an unnatural and brutal
treatment by his mother and his two elder brothers that he fled to
the protection of his sister Marguerite who had a great affection for
him; but here, too, he met with little favour from her hubsand who
put him to hard labour in the fields. He finally escaped from this
life of drudgery and was admitted to the seminary at Tubingen. Al¬
though he was a notably devout and religious man, he was expelled
for heterodoxy, a fate which dogged him all his life for, in those
early days of religious disturbance following the Reformation, it
was difficult to adopt any views which were not heterodox some¬
where in the tangled religious map of Germany. For a time, it
seemed as if the adverse stars of his horoscope had relaxed their in¬
fluence; he entered and made rapid progress at the University of
Tubingen, and was appointed professor of mathematics in Gratz at
the age of twenty-two. Here, he not only lectured but, to increase
his income, he compiled an annual almanach and cast astrological
horoscopes. These almanachs are a vivid example of his exuberance
of imagination and accuracy for details; interspersed with his predic¬
tions of the weather, he gave free rein to his passion for the numerical
harmonies of the Pythagoreans and a mystical identification of God
with the sun. His good fortune, however, soon forsook him since he
brought back his troubles by marrying a beautiful and noble widow
v/ho made his life a long martyrdom. Opposition to his religious
views also again cropped up, and he was finally obliged to leave
Gratz. This proved to be his one real piece of luck as he was ap¬
pointed assistant to Tycho at Prague in the preparation of the
Pmdolphine star catalogue and succeeded him, two years later, as
director of the observatory. It was there that he lived the rest of his
life and produced his immortal work, in spite of difficulties and sor¬
rows which would have broken the spirit of any one not devoted to
the pursuit of the highest ideals. He died at Ratisbon in 1630, while
on a journey made in the hope to collect his past due salary.

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272

Kepler’s first work was his Prodromus™ He was a convinced
Copernican and wrote the book to gain popular support to that
system. His opening words to the reader affirm his purpose: “I pro¬
pose to demonstrate to my readers in this little book what the
Creator Optimus Maximus was mindful of in the creation of our
mobile earth and in the disposition of the planets according to those
five regular geometrical bodies which, ever since to our times, have
been most renowned by the Pythagoreans and Plato; and how He
adapted the number, the proportions, and the cause of motion, to
the nature of those heavenly bodies.”

One can easily recognise in this youthful book Kepler’s belief
in a natural law or orderliness; that is, the planets must follow, in
their distances and periods, a definite sequence of numbers. Not
knowing any law of force which would account for the planetary
motions, and imbued with the Pythagorean and astrological belief
in the mystical harmony of numbers, he incorporated their ideas in
his scientific treatise. Thus, he first chose the five regular polygons
and then located the orbits of the planets by an ingenious arrange¬
ment of inscribed and superscribed circles. He was the more en¬
thusiastic over this scheme as he thought that he had disposed the
planets according to the proportions of a musical harmony. His
biographers express surprise, and even contempt, that Kepler should
have included a disquisition on music and the harmony of numbers
in an astronomical treatise; but they merely fail to sympathise with
the spirit of Kepler’s age, which found in musical harmony the
prototype of all natural law.

In the Prodromus, Kepler’s geometric and harmonious arrange¬
ment of the planets is briefly as follows. Locate the sun as the fixed
centre of the solar system, describe about it a sphere to locate the
orbit of the earth. 11 Construct a dodecahedron about the earth’s
sphere and on it circumscribe a sphere for the orbit of Mars. About
Mars construct a tetrahedron, and its circumscribed sphere will give
the orbit of Jupiter. In the same way, a cube and its circumscribed
sphere locate the orbit of Saturn. Next proceeding inwardly from
the earth’s sphere, an inscribed icosahedron and its inscribed sphere

10 The book was first published at Tubingen in 1596) and reissued at Frankfort in 1621,
with the portentous title: Prodromus dissertationum cosmographicarum, continens mysterium
cosmographicum de admirabili proportione orbium coelestium: deque causis coelorum nu-
meri, magnitudinis, motuumque periodicorum genuinis et propriis, demonstratum per quin-
que regularia corpora geometrica. Cf. also Vol.. I, Kepleri Opera Omnia, Ed. by Frisch,
Frankfurt, 1858.

11 For his model of the heavens see Opera, Vol. I, p. 215.

THE MECHANISTIC HYPOTHESIS

273

provide for Venus; and an octahedron and its inscribed sphere ac¬
count for Mercury.

However far Kepler’s fervent imagination might run away with
him, in the end he settled down to the hard task of verifying his
scheme by accurate calculation, and then confessed that he had fallen
into error. At another time, he said: “I dared, in order that the
beautiful harmony of quiescence may be maintained, to liken the
sun, the fixed stars, and the intermediate heaven, to God the Father,
the Son, and the Holy Ghost.” However erroneous his speculations
might prove to be, he took such a naive delight in them that he in¬
variably published them in as great detail as he did his sober scientific
work. Fortunately, on the advice of Tycho, he laid aside these
vagaries and applied himself to the strict business of astronomy. It
was not until 1609, the year the telescope was discovered, that he
finally found his master laws of the solar system and published them
in his Nova Astronomia , 12 It was also fortunate that Tycho had
made a special study of Mars, so that when Kepler became his as¬
sistant and successor he had a great collection of accurate data about
that planet to digest and to analyse. Since the orbit of Mars is the
most eccentric of all the planets and thus departs most from a circle,
he quickly found that the discrepancies between his calculations and
Tycho’s observations were too great to be due to errors in observa¬
tion. He finally became convinced that a circular orbit would have
to be abandoned. His first guess was to assume some form of an
oval 13 and with incredible patience he tried many varieties before he
finally satisfied himself that the orbits of all planets were ellipses
with the sun fixed at one of the foci. His second law, that the areas,
swept in equal periods of time by a line drawn from the sun to the
planet, were equal, followed at once from the geometrical properties
of the ellipse. The number and extent of the calculations he made to
prove these two laws are astonishing and he, at one place, interrupts
his work to exclaim: “If you find this work difficult and wearisome
to follow, take pity on me, for I have repeated these calculations
seventy times, nor be surprised that I have spent five years on this
theory of Mars.” But Kepler was still not satisfied; obsessed with the
Pythagorean doctrine of the harmony of the stars, he persisted in
trying to find some proportionate relation between the planets. His
joy, which he poured out in fervent thanks to God, knew no bounds

12 Published at Prague, 1609, and reprinted as Vol. Ill in his Opera.

13 “Orbitam planetae non esse circulum, sed figurae ovalis.” Opera, Vol. Ill, p. 337.

ISAAC NEWTON

274

when he at last proved his third law that the cubes of the mean dis¬
tances of the planets from the sun are proportional to the squares of
their annual periods.

With the establishment of the three laws for the motion of a
planet, or satellite, about a fixed central body, Kepler had solved the
essential, or schematic, problem of the solar system. The principle
which had led both Copernicus and him to their great discoveries
was the classical and purely metaphysical dogma that Nature al¬
ways adopts the simplest and most nearly symmetrical course. This
doctrine is unfortunately not true in fact, and it has been the source
of many pernicious hypotheses. When the classification of a new
set of observed phenomena is first attempted, it is inevitable that only
their most salient features are considered, and the law derived from
them is simple. For example, when Galileo first discovered the law
that the path of a projectile is a parabola, he excluded the friction
and motion of the air, variations in the force of gravity, and many
other perturbations. If these so-called secondary actions are included,
the actual path of any projectile is a curve so complicated that its
form cannot be expressed by a soluble mathematical equation, and
an approximate solution only can be obtained. As a general thesis we
must admit natural phenomena are actually so complex and inex¬
tricably interwoven that we can never isolate any one set of phenom¬
ena nor attempt to picture the actual history of events. Nature, as
studied by the physicist, is thus a simplified and artificial world
which bears but a faint resemblance to an objective universe. No
better illustration of this fact could be given than the history of the
laws of the solar system. Copernicus first assumed the general law of
circular orbits. The discrepancies between the calculated and ob¬
served positions of the planets soon became so apparent that Kepler
substituted the less simple elliptic path. But this law presupposes
that there is an action between two bodies only, the central body and
its satellite; whereas the fact is, every body of the solar system at¬
tracts every other body with a constantly varying force and the
problem of plotting the actual path of a planet is totally beyond our
powers. Instead of an elliptical path invariably pursued, the actual
course of a planet is much more like the erratic trail of a drunken

man.

Great as was the achievement of establishing the heliocentric sys¬
tem, there still remained the question, why must a satellite revolve
about its central body in an ellipse ? Aristotle had assumed that the

THE MECHANISTIC HYPOTHESIS

275

circle was the only perfect curve and that the heavenly bodies, being
composed of a perfect and celestial substance, must of necessity move
in circles. This teleological principle maintained its authority as an
effective cause all through the middle ages and was not questioned
by Copernicus, whose only contribution to the subject was that mat¬
ter had a natural appetency to congregate into a spherical form and
that a falling body was merely a manifestation of this inherent quality.
Nor did Tycho Brahe attempt any solution of the problem of the
cause of planetary motion; but his work did contribute indirectly to
the discovery of a force of attraction by destroying the belief in solid
celestial orbs which supported the planets in space. He proved that
the comet of 1577 was at ^ east three times farther from the earth than
was the moon. Thus, these mysterious visitors were not local
phenomena but bodies which freely penetrated the solar system in
all directions.

One can readily understand that Kepler, with his eager and rest¬
less imagination, not only pondered over the question of planetary
forces but would hazard a multitude of guesses. Having no concep¬
tion of the resultant action of a force directed perpendicularly to
the motion of the planet, he sought for one which would drag it, or
whirl it, around the sun. In his Mysterium cosmographicum he as¬
signed to the sun a sort of living principle {animus) which moved
and regulated the planets. In the meanwhile, Gilbert had published
his great treatise De magnete, containing an extraordinary wealth of
experimental observations on electricity and magnetism, which
profoundly impressed both Kepler and Galileo, drawing from the
latter a rare tribute of appreciation. Gilbert not only by his experi¬
ments advanced these subjects to real sciences but, having described
the earth as a great magnet, he supposed gravitation to be a magnetic
force whose influence extended even as far as the moon. His hy¬
pothesis was further elaborated in a posthumous work. 14 “It is
not,” he says there, “so as to make the bodies unite like two magnets,
but that they may go on in a continuous course.” And again: “The
moon does not act on the tides of the seas by its rays or its light.
How then ? Certainly by the common effort of the bodies, and (to
explain it by something similar) by their magnetic attraction.” He

14 De mundo nostro sublunari, Philosophia nova, Amsterdam, 1651. The manuscript of
this work was found amongst Gilbert’s scattered papers and was translated and prepared for
publication by his elder brother. For some reason it was not published and was found
amongst Francis Bacon’s manuscripts., It was finally published by Bacon’s literary executor,
Isaac Gruter.,

ISAAC NEWTON

276

thought that this cosmic magnetic force dragged the moon around
the earth as the earth spins a magnetic compass needle, and also that
it rotated the earth on its axis. Kepler had early become acquainted
with the De magnete and, when he discussed the cause of planetary
motion in his own Astronomia nova, he eagerly adopted the same
hypothesis. He summarised Gilbert’s views on magnetism and
added: “Since the earth, as demonstrated by William Gilbert of Eng¬
land, is a great magnet and is rotated on its axis daily, so I believe the
sun to be rotated: and for this reason, because it has magnetic fibres
intersecting the direction of its motion at right angles in the same
way as those fibres surround the poles of the earth in varying circles
parallel to its motion: so I maintain with the best right that the moon
is whirled about by this rotation of the earth and by the action of this
same magnetic virtue. ... It is therefore plausible, since the earth
puts the moon in motion by its effluvium ( speciem ), and is a mag¬
netic body, that the sun puts the planets in motion similarly by an
emitted effluvium ( emissam speciem ): Solem itaque similiter corpus
esse magneticum ." 1B

Although Galileo was not an astronomer, his invention of the
telescope put into their hands so powerful an aid that we may safely
ascribe to him the overthrow of mediaeval astrology; and his creation
of the science of dynamics substituted a correct idea and formula for
force instead of those vague and useless effluvia and virtues which
had been postulated as efficient causes of phenomena. As early as
1590, he had, by his spectacular experiment of dropping balls of
different weights from the leaning tower of Pisa, proved that the
force of gravitation was not proportional to the velocity of motion,
and had thus crushed by experimental demonstration one of the
fundamental doctrines of Aristotle. It is said; those who observed
the experiment acknowledged that the various bodies appeared to
reach the earth at the same time, but they stubbornly maintained that
it must have been an optical illusion since the great Stagirite had de¬
clared a body six times as heavy as another must fall the same dis¬
tance in one-sixth the time. With this incident, began his life-long
controversy with the Aristotelians, a struggle to which he devoted his
great power of experimentation, of logic, and of biting satire; until
his adversaries, driven to desperation, finally invoked the aid of the
Church with the accusation of heresy. So bitter was Galileo’s satire,

15 Astronomia nova, Chap. XXXIV, p. 307. Ed. Frisch. The word species, in scholastic
epistemology, was used to express the processes leading both to sense and to intellectual
knowledge. Many writers used it as the cause of action, as an effluvium or virtue.

THE MECHANISTIC HYPOTHESIS

277

and so biting his sarcasm that in early life he was hissed during his
lectures at Pisa, and forced to resign and return to Florence. For¬
tunately for himself and for the world, he obtained a professorship
of mathematics at Padua, where under the protection of Venice, the
only state in Italy having the power and will to oppose the authority
of the monastic orders and the Inquisition, he publicly experimented
and lectured for twenty years, attracting by his fame young men
from all Europe who came to learn the new knowledge at its source.
In his first letter to Kepler, written in 1597 to acknowledge the re¬
ceipt of the Mysterium cosmographic urn, he declared that he had be¬
come a convert to the Copernican system many years before. Teach¬
ing the doctrine openly as a fact and not as an hypothesis, he created
adherents and scattered them all over Europe.

The climax to his fame came with the invention of the telescope;
requests for one of these magic instruments poured in on him from
all parts of the world and he literally made hundreds of them with
his own hands; to gaze through a telescope became the fashionable
amusement of courts and society, and the serious occupation of the
astronomer. Distracted by this manual labour, by the interruptions
of curious visitors, and by the burden of correspondence, he found
little time to pursue his scientific work. With the promise of leisure
offered to him by his friend Duke Cosimo II, he forsook the pro¬
tection and safety of Padua and Venice for the dangers of Florence
and Pisa, where his enemies were lying in wait for him. The religious
influence of his opinions was first attacked by Boscaglia, Professor of
Physics at Pisa, who excited the scruples of the Dowager Duchess on
the ground that a belief in the two motions of the earth was con¬
trary to the Bible. Galileo’s tactful answer was to cite Joshua’s
miracle as an example of puerile folly. He was also preached against
by the Dominican Caccini in the Duomo of Florence and mirabile
dictu supported by a Jesuit. But, for once the Aristotelians, Domini¬
cans and Jesuits, united against a common enemy and gave thanks
that the Lord had delivered him into their hands. No opposition to
Galileo had as yet been aroused in Rome and the Pope, Paul V, was
favourable to him. But the pressure from Florence finally prevailed
and he was cited before the Inquisition. He was, after many delays,
admonished, in 1616, by the Holy Office to renounce his heresy, and
Copernicus’s treatise was suspended and placed on the Index until
corrected, a sentence which was not formally revoked until 1835.
Galileo returned to Florence sick and despondent.

ISAAC NEWTON

278

To force the issue, as Galileo had persistently done, and to inject
personal attacks into a question to be ultimately decided by observa¬
tion and reason, can be regarded as most unfortunate in its effect on
both religion and science. Many of those who privately accepted the
new science were compelled to express a public disapproval of its
teachings. Kepler openly lamented the set-back which had been
given to the quiet and steady spread of the doctrine. As early as
1619, John Remus wrote from Vienna to Kepler that the Copernican
writings may be read by scientific men who had received special per¬
mission, and that this was common in all Italy and in Rome, itself.
Besides, it was allowed to make use of the doctrine as an hypothesis.
We should realise that it was then not supported by sufficient facts
and that the Church was in a most awkward position; as a scientific
device to simplify mathematical calculations there would be no fault
to be found, but taught as a fact, the two-fold revolution of the earth
was clearly contrary to those religious beliefs of the day which the
authorities were bound to uphold.

It was not, however, a trait of Galileo’s character to submit docilely
to authority. In 1623, the Cardinal Maffeo Barberini became Pope
Urban VIII; as he was most favourable to science and a personal
friend, Galileo visited Rome the following year but, although he was
received with favours and gifts by the Pope, he could not get the
former decree revoked. Encouraged with his reception, he spent the
next three years writing his Dialogues on the two principal systems ;
strangely enough, his manuscript was approved by Urban who
merely required a few alterations and, after some delay, permission
was given to publish. It was a rash deed and even more rashly
done. In these celebrated Dialogues, Galileo not only rudely dis¬
pelled the fiction that the Copernican system was merely a mathe¬
matical hypothesis, but he subjected the Jesuits and Aristotelians to
the bitterest ridicule. The spirit of malice and irony in which it was
written can be judged from the opening sentence of the preface:
“There was promulgated at Rome, some years ago, a salutary edict,
in which to obviate the perilous scandals of the present age silence
has been imposed on the Pythagorean opinion of the motion of the
earth. There are some people so rash as to believe that this decree
was not the result of a judicious examination but of a passion too lit¬
tle informed; and complaints even have been heard that Councillors
totally ignorant of astronomical observations ought not, with a pre¬
cipitate prohibition, to cut the wings of speculative men of intellect.”

THE MECHANISTIC HYPOTHESIS

279

Under the form of a dialogue, the author then unfolds the new doc¬
trine, and exposes the fallacies of the Aristotelians with bitter and
scathing contempt.

The book was a great masterpiece of science and of literature, and
it made an immense sensation over all Europe. But it also gave his
enemies just the opportunity they needed to bring him to trial for
heresy. They were able even to give credence to the rumour that
Simplicio, the butt of the dialogues, was a caricature of the Pope.
Spurred to action, the Congregation of the Index Erst ordered the
sale of the book to be stopped and, in October, summoned its author
to Rome. Then followed months of anxiety and terror, during which
Galileo could only guess what was to be his fate. His first examina¬
tion did not take place until April, and his sentence was deferred
until June 22. Everyone knows the dramatic scene when finally the
proud and haughty old man abjured publicly those ideas as false
which he had given his life-time, and his great genius, to prove as
true. He was furthermore forbidden to teach or to write, and was
exiled to the villa of the Grand Duke of Tuscany. We may admit
that the doctrine was heretical and that the sentence was compara¬
tively mild; but there is no shadow of doubt that it was a colossal
blunder; the trial of Galileo is still cited as an example of the bigotry
and dogmatism of the Roman Church, and at the time it turned
thoughtful people away from her congregations; one would be more
ready to pardon her if one did not more than suspect that many of
the judges secretly accepted the Copernican system as the truth.

Although Galileo was broken in health and harassed by domestic
misfortunes, he heroically used his enforced leisure to collect and
prepare for publication the results of his years of study on mechanics.
This treatise, with the title of Dialoghi delle nuove scienze , 1G is un¬
doubtedly his masterpiece and contains practically all that he had to
give on the subject of physics. Since Galileo could not hope to print
in either Florence or Rome, he turned to Venice for a publisher, but
was blocked by the information that there was an express order

16 It was first published by the Elzevir Press in 1638. It was translated into English by
Thomas Salusbury in 1665, and not again till recently by Professors Crew and De Salvio
under the title of The Two New Sciences, Macmillan, 1914. The authors make mention of
Salusbury’s translation: “It is supposed that most of the copies were destroyed in the great
London fire which occurred in the year following.. We are not aware of any copy in Amer¬
ica: even that belonging to the British Museum is an imperfect one.” The first complete
edition of Galileo’s Works was published under the editorship of Eugenio Alberi, Florence,
1842-1856, in sixteen volumes. Quite recently Professor Favaro of Padua has edited the
National Edition in twenty volumes.

280

ISAAC NEWTON

prohibiting the printing or reprinting of any work of Galileo, nullo
excepto . He next turned to Germany and, although he obtained per¬
mission to publish, he still feared the long arm of the Court of Rome.
Finally, availing himself of a visit from Louis Elzevir, he gave to him
the manuscript to take back to Leyden, where it was published in
1638. Galileo’s life, full of great achievement and bitter sorrow,
came to an end on January 8, 1642; on Christmas of the same year
there came into the world an even greater philosopher, Isaac New¬
ton. We may make the history of dynamics and the mechanistic
philosophy run with these two lives which spanned the century and
a half, from 1564 to 1727.

On the third day of the Dialogues on the new sciences, Galileo
discusses the laws of motion and force. The notion prevailed that
force was proportional to the velocity of a body; it was therefore as¬
sumed that a constant force was required to maintain a body at a
uniform speed, and also that a body, weighing twice that of another,
falls twice as fast and reaches the earth in one-half the time. So far
as we know, no one before Galileo had tested this latter assumption;
and it was a simple matter for him to show its error by observing the
free fall of two bodies of very different weights, enclosed in boxes
of the same size and shape to ensure an equal resistance of the air.
To test the law of gravity accurately, by measuring the time of the
free fall of a body, would have been impossible with his crude tim¬
ing apparatus, since the free fall is swift and the time is short.
Galileo cleverly avoided this difficulty by substituting the slower mo¬
tion of bodies rolling down an inclined plane. He first proved that a
free, or vertical, fall is merely a special case of an inclined plane
whose inclination to the horizontal is ninety degrees, and that the
law of force and motion is the same for inclined planes of any
angle. He next proved experimentally that bodies of all kinds, mov¬
ing down an inclined plane, experienced a constant and equal ac¬
celeration, or increase of velocity per second of time, whose amount
depended only on the inclination. It followed immediately that all
bodies, of whatever kind and weight, fall from rest with the
same acceleration and reach the earth from the same height in
equal times if we neglect the friction of the air. Thus force is in¬
dependent of the velocity, since it is proportional only to the change
of velocity per second, and is measured by this acceleration. He had
thus derived an experimental and theoretical proof of the law which
he had roughly demonstrated so many years before from the tower

THE MECHANISTIC HYPOTHESIS

281

of Pisa; that all bodies fall to the earth with the same velocity and
in the same time, because the force of gravity produces the same ac¬
celeration in all bodies. Also, from his experiments and theorems on
inclined planes he derived a most important deduction as follows:
“Moreover it is proper to assume that any velocity observed in a mov¬
ing body is, on account of its very nature, unchangeable so long as
external causes of acceleration, or retardation, are taken away, a con¬
dition which obtains only on a horizontal plane: for in motion down
an inclined plane there always exists a cause of acceleration, and in
motion up an incline there is retardation. From which it follows in
like manner that motion on a horizontal plane is everlasting and un¬
changeable: if it is thus constant, it will be neither weakened nor
slackened and much less destroyed. 17 This is a statement, in no
vague terms, of Newton’s first law of motion, which he generalised
to include the motion of all bodies not acted upon by forces. Also,
Galileo’s assumption, that the force of gravity and the upward re¬
sistance of a horizontal plane on which a body lies are equal and op¬
posite is an anticipation of Newton’s third law of the equality of
action and reaction. The passage quoted shows that Galileo had de¬
fined the law of conservation of momentum; it is evident, also, that
he, for the special case of gravity, anticipated Newton’s second law
that a force acts only in the direction of acceleration and is measured
by it.

The discussion of the fourth day is devoted to the motion of
projectiles, the paths of which he proved to be parabolae. In the
course of the conversation, Sagredo sums up: “It cannot be denied
that the discourse is new, ingenious, and conclusive, reasoning ex
suppositione, on the hypothesis that the horizontal motion remains
always constant and that the natural motion downwards likewise
preserves its tendency to increase the motion constantly in direct
proportion to the time; and such motions and their velocities, when
blended together, do not alter, perturb and impede each other. So
that finally the path of the projectile does not in the course of its
motion degenerate into another type.” 18 This passage is certainly a
particular case of Newton’s second law of motion. Although it re-

17 Ed. Alberi, Vol. XIII, p. 200.. Also translated by Crew, p. 214.

18 Ed. Alberi, Vol. XIII, p. 227. Professor Crew in his translation of this passage, see p.
250, renders “il naturale deorsum parimente mantenga il suo tenore di andarsi sempre
accelerando secondo la proporzion dei tempi” as “the vertical motion continues to be
accelerated downwards in proportion to the square of the time.” This rendition seems
to me to alter Galileo’s meaning which is that the acceleration downwards is constant dur¬
ing the time of motion.

282

ISAAC NEWTON

quired many years before it was developed by Newton into his law of
universal gravitation, the intermediate steps are easily followed. If
a body be moving with a uniform velocity in a circle, then there can
be no force along the arc of the circle, as Galileo proved for the case
of the projectile; and the only force present must be directed at right
angles to the motion, or along the radius. From this deduction by
Galileo, Huygens 19 derived his general law of centrifugal force, and
Newton, his solution of Kepler’s law some time between 1667 and
1687.

In an interesting essay 20 on the sources of Newton’s ideas on the
principles of mechanics, Professor Child expresses the opinion, which
he frankly confesses to be a guess, that the inspiration for the pre¬
liminary matter of the Principia came from the work of Baliani. He
states that his guess would be justified if, “after a careful search into
the works that were in Newton’s library, there is found a copy of a
certain book, especially if it shows signs of having been much used,
or if in any of his manuscripts a certain name occurs; and I will
gladly acknowledge the error of my ways if such a book is not to be
found. The book is De Motu and the author is Baliani.” My own
reading of the De Motu leaves me with the opinion that any connec¬
tion between Baliani and Newton is extremely doubtful. His treat¬
ment of the problem of forces seems far more limited and obscure
than that by Galileo. And the chance that this work by an obscure
Italian was known to Newton and his contemporary English natural
philosophers is far less likely than that the Dialogues of the most
eminent man of science of the age were not familiar to them. The
Dialogues on the Two New Sciences had been translated into Eng¬
lish in 1665 and, although the edition may have been destroyed in
the London fire of the following year, the original or some copies
must have been well known and studied. 21

If we turn to Newton, himself, for the sources of his ideas, we ob¬
tain very little information. For his discovery of the problem of the
moon’s force in 1666, we gather that he developed the law of in-

19 Cf. Horologium Oscillatorium, published in 1673.

20 Cf. Isaac Newton, 1642-1727. Ed. by Greenstreet, p. 117.

21 For Professor Child’s discussion of this point, cf. Greenstreet, pp. 125-129. As for
Newton’s manuscripts, I have found no reference in any of them to Baliani; this is not
conclusive as it is certain that many of them were destroyed and others have not been dis¬
covered. As for his library, since Professor Child wrote his essay Col. de Villamil has
found and published the complete catalogue of Newton’s books, as inventoried at his
death, and no work by Baliani is included. Professor Child makes a slight error when
he states that the first book of his De Motu was published in 1639; it bears the imprint,
Genoa, 1638. His guess, also, has not been substantiated.

THE MECHANISTIC HYPOTHESIS

283

verse squares from a direct study of Copernicus and Kepler with the
mathematical aid of Descartes, Barrow, and Wallis. In the Pnncipia,
he mentions Galileo as the source from which he formulated his
first and second laws of motion; and from the work of Wren, Wallis,
and Huygens on the laws of impact, he obtained his third law. It is
significant of his dislike for Hooke and Descartes that he omits their
names. The law of attraction, as being proportional to the inverse
square of the distance, he states was surmised by Wren, Hooke, and
Halley and he specifically mentions that Huygens had compared the
force of gravity with the centrifugal forces of revolving bodies. In
his correspondence with Halley, the statement is made that Borelli
had contributed something to the discovery and had written modest¬
ly about it, but Hooke had published Borelli’s hypothesis as his own.
He also gives credit to Bullialdus for a share in its history. While
Descartes should be considered as one of the great contributors to the
mechanistic hypothesis and, in fact, elaborated a vast cosmical sys¬
tem on that doctrine, his invention of vortices to carry the planets
about the sun was the chief obstacle to the acceptance of New¬
tonian mechanics; and Newton took great pains to expose the failure
of the vortical theory in a manner which clearly showed his satis¬
faction.

Although Newton stated explicitly that Borelli and Bullialdus 22
had arrived at the correct law of gravitation and also intimated that
their views had been of aid to him in his own work, the various
commentators on the Principia are quite divided in their opinions as
to whether any such conclusions can be derived from the works of
those two authors. It seems to me we might accept Newton’s testi¬
mony rather than their opinion that those authors, whether wit¬
tingly or not, had contributed something of real importance to that
great discovery. At least we can let them speak for themselves.

Bullialdus (or Bouilleaud, 1605-1694), a French astronomer, was
an accurate and voluminous observer whose data on the orbits of the
planets were quoted as authoritative by Newton in the Principia.
He was an enthusiastic supporter of the Copernican system; and was
so convinced, that the success of the new science was dependent on a
revival of the Pythagorean and Platonic scientific conceptions, as to
name his most important treatise the Astronomia PhilolaiccP 3 to in¬
dicate his belief that Philolaus, the Pythagorean, was the founder

22 It is interesting to note, in connection with Professor Child’s “guess,” that the works
of Borelli are listed in Newton’s library, but that none of Bullialdus’s is mentioned.

23 Ismaelis Bullialdi Astronomia Philolaica. Paris, 1645.

284

ISAAC NEWTON

of the true astronomy. The work is one of the most important of the
period. It contains a valuable summary of the history of astronomy
and a wealth of data. While he gives proper credit to Kepler, he ac¬
cuses him of advancing an erroneous hypothesis of planetary mo¬
tions. The portion of the work, which discusses this hypothesis, is
contained in the twelfth chapter of the first book, headed An sol
moveat planetas. He combats Kepler’s idea that the motive force of
the planets resided in the sun which was endowed with a species,
or effluvium, of a spiritual or magnetical nature, and whirled those
inert bodies about him in their orbits. While he adduces four ob¬
jections, the significant reasons he gives are first; if the planets are
thus inert, how do they, the earth and Jupiter for example, move
their own satellites and, secondly, he denies that there are any such
whirling forces. In the course of his argument, he affirms that the
planetary force is one which acts along the line joining the two
bodies and decreases inversely as the square of the distance between
them. 24

One of the earliest attempts to explain all phenomena by means of
atoms, or corpuscles, which were subject only to mechanical laws,
was made by Giovanni Alfonso Borelli 25 (1608-1679), a Neapolitan,
and the most distinguished member of the Accademia del Cimento.
In brief, his fundamental postulate was that all natural actions are
caused by a gravitational force on the corpuscles which pulls them
towards the centre of the earth according to mechanical laws; but the
particular forms of the corpuscles and their mutual linkages divert
their downward motion into other directions. Thus, aggregations
of corpuscles are like machines whose prime motive force is gravity,
but whose construction is so designed as to make them operate in
various ways. The dilemma which faces all mechanists is how to
give an active principle to atoms which are essentially inert and
passive. The problem is really insoluble and the usual method is to
create an hypothetical substance which complacently does all those
things which may be needed. So Borelli asserts that there are also

24 The passage ( Cf. p. 23) is quite explicit although the reasons are specious: “Virtus
autem ilia, qua Sol prehendit seu harpagat planetas, corporalis quae ipsi [Kepler] pro manibus
est, lineis rectis in omnem mundi amplitudinem emissa quasi species solis cum illius corporc
rotatur: cum ergo sit corporalis imminuitur, et extenuatur in majori spatio et intervallo,
ratio autem hujus imminutionis eadem est, ac luminis, in ratione nempe dupla virtutem
motricem in simpla tantum ratione inu (t) ervallorum contendit imminui.”

25 His most important works on physics are: Theorica mediceorum planetarum ex causis
physicis deducta, Florence, 1666; De motu animalium, opus posthumum, Rome, 1681; De
motionibus naturalibus, a gravitate pendentibus, Lugeluni Bataborum, 1686.

THE MECHANISTIC HYPOTHESIS

285

certain aethereal and living (spirituosa et vivida) particles which
were endowed with the attribute of self-motion by God at the crea¬
tion. The otherwise inert material bodies enmesh in their pores a
multitude of these active aethereal corpuscles and so he accounts for
the forces of gravity, magnetism, etc. This hypothesis has so many
points of resemblance with Newton’s speculations on an aether that
he very probably was influenced by it. Borelli’s contribution to
Kepler’s problem is found in his study of Jupiter’s moons. He re¬
marks that, when a body revolves in an orbit, it has a tendency to
recede from its centre of revolution as mud from the rim of a wheel,
or a stone whirled by a sling. When this force of recession is equal
to a force of attraction pulling it to the centre, the body will neither
approach nor recede from the centre but will continually revolve
about it, and a planet will appear balanced and floating on the sur¬
face of a sphere.

This statement brings us down to the time of the active work of
Newton, and may well close our summary of the growth of the
mechanistic hypothesis which he completed by his discovery of an
universal law of attraction. However much we may respect his
predecessors, we cannot fail to recognise that their ideas were vague
and that no organised scientific method could be derived from them.
If we may personify Nature and give to her the attribute of choice,
we may then say that out of all the human race she granted to New¬
ton the unique destiny of disclosing her profoundest secret. All that
was needed was a mathematical apparatus capable of expressing the
changes of path of a body under a constantly varying motion. The
classic geometry, dealing with static problems, was inadequate. But
the expansion of mathematical analysis during the Renaissance was
even more rapid than was that of astronomy and physics. Descartes
made the first great step by his fusion of algebra and geometry. This
powerful analysis was developed into the method of solving problems
of curvilinear motion by expansion into infinite series; the final step
was the invention of the calculus, or summation of infinitesimal
variations by Newton and Leibniz.

CHAPTER IX

THE PRINCIPIA
1685-1687

W hen the curious in such matters, filled with a sort of awe
because of the marvels of Newton’s mind, enquired of him
to what quality he owed a success which they characterised
as superhuman, they obtained but little satisfaction. He could
ascribe his success only to a patience and perseverance which he
thought may have surpassed somewhat that of other men; he could
discover in himself no peculiar sagacity, or especial genius. But this
is no answer at all; no amount of patience and perseverance can
achieve such results unless they are based on what we vaguely call
genius or intuitive insight, a quality which seems mysterious because
we cannot follow its logical operations. It is safe to affirm that the
history of science offers no parallel to the achievement by Newton of
three capital discoveries in the interval of two years; this achieve¬
ment is enhanced by the fact that they were made by a youth in his
second decade and without preparatory labour.

And because Newton limited his scientific work to the formulation
of laws, and restrained his imagination from making hypotheses as
to how nature operates, his great discoveries and laws are classic and
permanent. The attraction of matter as a universal force is unques¬
tionable, and the deductions he made from it are true so long as
mathematics can express the truth. His law, that this attraction
varies as the inverse square of the distance, may be an approximation;
we may find that the exponent two is either a little too great or too
small; and other influences may modify the effects of such attraction.
But the law itself cannot be overthrown as can be an hypothesis,
which attempts to explain the nature of matter or the mechanism of
its action; such laws can only be made more precise.

Unlike his early work on light, which was carried on consecutively
and was published currently in the Philosophical Transactions, New¬
ton’s first calculation of the attraction on the moon was laid aside,
and the subject incubated in his mind for twenty years. When he

286

THE PRINCIPIA

287

finally published his Principia, the world was amazed with the re¬
alisation that the new science, begun by Copernicus, had been
brought to fruition, and that a new philosophy of life had been born.

There are several reasons why the discussion of Newton’s Prin¬
cipia should be treated by a biographer differently from that given in
connection with his discoveries in light. In the first place, with the
exception of a certain amount of spluttering by Hooke, there was
no controversy. It was at once recognised that here was a work of
such transcendent quality, that merely to follow its conclusions
would tax the ingenuity of the best minds, and that no living persons
could challenge its originality or power. Newton had become the ad¬
mitted dictator of scientific thought, and there was no one able to
cross swords with him. It was expedient to give in some detail the
particulars of his work on light and of the controversy which re¬
sulted,—not because of the value of the facts involved, but because,
out of that controversy, there came the clear enunciation of his prin¬
ciples of the scientific method and its limitations. It was the miscon¬
ception of that work, and the inability of his opponents to distinguish
between theory and hypothesis, which finally made him resolve to
eliminate from his later masterpiece all discussion of why and how
nature worked, and to announce his famous motto, hypotheses non
fingo. And so far as I know, his Principia does follow more closely
that precept than any other scientific treatise: and for that reason,
his mechanistic theory has been developed as new knowledge has
been acquired; it has been criticised, and its errors have been cor¬
rected till, in its legitimate field, mechanics is the most nearly perfect
of all the sciences; it cannot be superseded, and it must remain the
fixed corner-stone of all mechanistic science. If Newton’s distinc¬
tion between natural theory and hypothesis, between humanism and
science, was made clear in that earlier discussion, it is not necessary
to repeat it; to emphasize it then seemed to be opportune because of
late there has been a renewed outburst of unrestrained speculation by
mathematical physicists, who have forsaken the sober paths of scien¬
tific achievement in order to indulge in pure symbolism, and have
invented a universe whose phenomena and laws have no corre¬
spondence with our sense perceptions.

There is also no need to discuss in detail the scientific conclusions
of the Principia as they have been the theme of almost countless
commentators. This work has been done by Lagrange, by Laplace,
and by others. And those readers who have the technical equipment

288

ISAAC NEWTON

can readily turn to them. As for its philosophical influence on
science, on pseudo-science, on society, and especially on religion, the
field is too large to be incorporated in a biography and should be the
subject of a special study. The Principia has been a great reservoir
from which mechanistic philosophers have drawn their ideas and, in
spite of Newton’s warning, they have applied it to all sorts of prob¬
lems which lie outside the field of mechanics, and even of physics.

The history of Newton’s Principia takes us back again to the time
when he spent the greater part of the years, 1665 and 1666, quietly at
Woolsthorpe to escape the plague. He had just been graduated from
college and had been successful enough to be appointed to a scholar¬
ship. As a boy, he had spent his days on the farm, meditating on the
childish problems which interested him, and now as he comes back,
a man, he takes up again his former life; but his mind is now full of
profound ideas, and his meditations are to change the course of all
future thought. In the long summer afternoons, he sits in the
orchard which still stands near the old gray stone house; on one
memorable day, an apple falls with a slight thud at his feet. It was a
trifling incident which has been idly noticed thousands of times;
but now, like the click of some small switch which starts a great
machine in operation, it proved to be the jog which awoke his mind
to action. As in a vision, he saw that if the mysterious pull of the
earth can act through space as far as the top of a tree, of a mountain,
and even to a bird soaring high in the air, or to the clouds, so it
might even reach so far as the moon. If such were the case, then the
moon would be like a stone thrown horizontally, always falling
towards the earth, but never reaching the ground, because its swift
motion carried it far beyond the horizon. Always falling towards
the earth and always passing beyond it, the moon would follow its
elliptical path if these two motions were equally balanced. How
simple the idea seems to us now as we look backwards, but how
difficult it was to foresee can be gathered from the fact that even a
Galileo, who had solved the problem of the projectile, did not have
sufficient imagination to guess that the moon was only a projectile
moving swiftly enough to pass beyond the earth. Nor could Huy¬
gens, who formulated the laws of centrifugal force and motion,
penetrate the secret. Perhaps even more significant of Newton’s
genius, was the fact that he not only guessed the law of attraction,
but he immediately set himself the task of calculating what would be
the law of the force which could hold the moon in her orbit.

THE PRINCIPIA

289

All that we know about the initial step of this greatest of discov¬
eries is that Newton did make a calculation to see if a force of attrac¬
tion, which varied as the inverse square of the distance between the
two bodies, would account for the laws of planetary motion; and,
having fairly well satisfied himself of its truth, he laid the problem
aside to think about other things. Nor did he make any record, at
the time, of the sequence of his ideas; and he apparently was unable
to tell the story accurately after some years had passed. The earliest
account of his discovery was given, in 1694, by Newton to Whiston,
who reported it as follows

‘TJpon Sir Isaac’s first trial, when he took a degree of a great cir¬
cle on the earth’s surface, whence a degree at the distance of the
moon was to be determined also, to be 60 measured miles only, ac¬
cording to the gross measures then in use. He was, in some degree,
disappointed, and the power that restrained the moon in her orbit,
measured by the versed sines of that orbit, appeared not to be quite
the same that was to be expected, had it been the power of gravity
alone, by which the moon was there influenc’d. Upon this disap¬
pointment, which made Sir Isaac suspect that this power was partly
that of gravity, and partly that of Cartesius’s vortices, he threw aside
the paper of his calculation, and went to other studies. However,
some time afterward, when Monsieur Picard had much more ex¬
actly measured the earth, and found that a degree of a great circle
was 6 g l / 2 such miles, Sir Isaac, in turning over some of his former
papers, light upon this old imperfect calculation; and, correcting his
former error, discover’d that this power, at the true correct distance
of the moon from the earth, not only tended to the earth’s centre, as
did the common power of gravity with us, but was exactly of the
right quantity; and that if a stone was carried up to the moon, or to
60 semidiameters of the earth, and let fall downward by its gravity,
and the moon’s own menstrual motion was stopt, and she was let
fall by that power which before retained her in her orbit, they would
exactly fall towards the same point, and with the same velocity;
which was therefore no other power than that of gravity. And since
that power appear’d to extend as far as the moon, at the distance of
240,000 miles, it was but natural, or rather necessary, to suppose it
might reach twice, thrice, four times, etc., the same distance, with the
same diminution, according to the squares of such distances per-

1 Memoirs of Whiston. London, 1749, pp. 36-38. This passage is given verbatim, even
where the author’s sentence construction is certainly not all that it might be.

290

ISAAC NEWTON

petually. Which noble discovery proved the happy occasion of the
invention of the wonderful Newtonian philosophy.”

Pemberton, who edited the third edition of the Principia, gives
pretty much the same story of the error in the calculation, arising
from having taken the wrong diameter of the earth. According to
his account Newton, “being absent from books, he took the com¬
mon estimate in use among geographers and our seamen, before
Norwood had measured the earth, that 60 English miles were con¬
tained in one degree of latitude on the surface of the earth.”

We have one other account of the discovery and later development
of the law of gravitation drawn up by Newton, himself, sometime
about 1714. While there are some minor mistakes, it is, on the whole,
correct. This memorandum has been preserved in the Portsmouth
Collection? and is as follows:

“In the same year [1666] I began to think of gravity extending to
the orb of the moon, and having found out how to estimate the
force with which a globe revolving within a sphere presses the sur¬
face of the sphere, from Kepler’s Rule of the periodical times of the
planets being in a sesquialterate proportion of their distances from
the centres of their orbs I deduced that the forces which keep the
planets in their orbs must [be] reciprocally as the squares of their
distances from the centres about which they revolve: and thereby
compared the force requisite to keep the moon in her orb with the
force of gravity at the surface of the earth, and found them answer
pretty nearly. All this was in the two plague years of 1665 and 1666,
for in those days I was in the prime of my age for invention, and
minded mathematics and philosophy more than at any time since.
What Mr. Huygens has published since about centrifugal forces I
suppose he had before me. At length in the winter between the years
1676 and 1677 [probably this should be 1679 and 1680] I found the
proposition that by a centrifugal force reciprocally as the square of
the distance a planet must revolve in an ellipsis about the centre of
the force placed in the lower umbilicus of the ellipsis and with a
radius drawn to that centre describe areas proportional to the times.
And in the winter between the years 1683 and 1684 [this should be
the winter between 1684 and 1685] this proposition with the demon¬
stration was entered in the Register book of the R. Society.”

On the basis of Newton’s conversations with Whiston and Pem¬
berton, the tradition has thus come down to us that, having taken a

2 Portsmouth Collection, sec. I, div, X, number 41,

THE PRINCIPIA

291

wrong figure for the earth’s diameter, his calculated acceleration of
the moon towards the earth did not agree with what it should be, if
the attraction varied as the inverse square of the distance from the
earth. Such was his modesty and love of accuracy, so we have been
taught to believe, that he put away his calculations, supposing that
the force of gravity was not sufficient and that an unknown whirling
force, perhaps a Cartesian vortex, must be added in order to maintain
the moon in her orbit. It was also believed, on a statement of
Robison, that, when he afterwards learned of Picard’s more accurate
measurement of the earth’s diameter, he went home from London
and repeated his old calculations. When he saw his ideas were likely
to be confirmed, “he was so much agitated, that he was obliged to
desire a friend to finish them.”

In spite of the apparent straightforwardness and authority of this
tradition, there are many puzzling features connected with it which
make it difficult to accept. In the first place, Newton said of his work
that he had found his calculations to “answer pretty nearly.” Work¬
ing as he did at a place where he would not have reference books, he
should have been satisfied with an approximate result and, after all,
his result was only one-eighth too small. He also, at the time, ex¬
pected his calculation to be an approximation, as he supposed the
dimensions of attracting bodies affected the result; but he thought he
might, without a serious error, neglect the dimensions of the earth
and moon in comparison with the very great distance between them.
Finally, for simplification of the problem, he assumed the moon’s
orbit to be a circle instead of an ellipse. Thus, it seems that the error
in taking a wrong value for the earth s diameter, an error which it
will be shown could readily be corrected, is quite inadequate as a
cause why Newton laid aside this work for many years.

The statement, that Newton took an incorrect value of the earth’s
diameter, and thus made an error in his first rough calculation of the
law of gravity, is too well authenticated not to be accepted as true.
It is very probable, also, that he laid aside this problem, temporarily,
as he devoted himself to work on lenses and light. But, it is also
generally stated that this error was not corrected, and his calculation
repeated, till 1682 when he first became acquainted with Picard’s
new, and more accurate, measurement of the earth’s diameter. It is
important to discuss at length the history of one of the greatest of
scientific discoveries; especially, as it can be shown that there is no
likelihood that his early error delayed the publication of the Prin-

292

ISAAC NEWTON

cipia. Realising, however, the persistence of such a legend, when
once it has become established, there is little doubt that it will con¬
tinue to be cited by popular writers on science, even if a more rea¬
sonable explanation be advanced.

The reason commonly given for Newton’s careless adoption of an
inaccurate value for the earth’s diameter is that he was in the coun¬
try and, having no reference books at hand, he took the '‘local esti¬
mate of 60 miles per degree of latitude, used by old geographers and
seamen, instead of 69—(— miles.” Rigaud conjectures that he may
have been familiar with this figure because it had been published in
a text-book by Edward Wright, Fellow of Clare College. This may
be ingenious, but it is certainly not conclusive.

In the first place, it will be well to consider what authorities on the
measurement of the earth were available to Newton. There was un¬
doubtedly wide divergence of opinion, but fairly reliable data were
easily obtainable by him. 3 One of the most accurate determinations
of the earth’s diameter was made by Snell who computed 66.91
statute miles per degree of a great circle. The length of a statute
mile had been defined in 1593 as equal to 5280 feet. Now Snell’s
estimate had been accepted by Oughtred, and by Gunter, and books
by both of them were owned and read by Newton. If he used this
value, his error would have been less than four per cent.

Snell s value was also mentioned in Varenius’s Geography, which
was a standard text, so well known that Newton edited it in 1672.
But the most likely authority for him to consult was Norwood. He
had published his Trigonometry in 1631, and his Sea-Mans Practice
in 1636. He adopted the very convenient measure for seamen of
one nautical mile for each minute of latitude, or 60 nautical miles
per degree, and this practice is still in use. But he defined such a
mile as being equal to 6080 feet; thus his measurement is the quite ac¬
curate one of 69.5 statute miles per degree. It would seem then, if
Newton followed “the common usage of seamen” and took 60 miles
instead of 69.5? he must have overlooked the difference in length be-

«;^ T f e tK UnOUS k may ^ fil l d an e , lab . orate discussion of the facts known at the time about the
hv e3 r h - and th f,^ onfusi p n in , the standards of lengths, in a most valuable essay

by Professor Cajon on Newton s delay in announcing the law of gravitation” which
appeared in the memorial volume, "Sir Isaac Newton, 7727-/927” published by the History

Science Society, Baltimore, 1928.—'the writer also discusses the causes of the delay in
publishing: the Pnnctpta, and is convinced that it resulted from Newton’s inability to solve
the theoretical attraction of a sphere on an external point and so obtain a general solution
of the problem of attraction. I think, however, that Professor Cajori neglects an even more
important cause, Newton s temperamental procrastination and distaste for developing sys¬
tematically any mathematical problem. v ® y

THE PRINCIPIA

293

tween nautical and statute miles, and such a mistake should not have
long misled him.

Voltaire, however, stated, and he probably got the information
from Mrs. Catherine Barton, that Newton was unacquainted with
the work both of Snell, and of Norwood, whose measurement had
been completely forgotten during the disturbances of the civil wars.
But it has already been shown that Snell’s value was quoted by
Gunter and by Oughtred. As for Norwood, the statement is certainly
wrong; the fourth edition of his Trigonometry was published in
1661 and the seventh edition of the Sea-Mans Practice in 1667, which
is sufficient evidence that his work was not forgotten.

It thus seems certain that Newton could easily have found a suffi¬
ciently accurate measure of the earth’s radius. Just when he recalcu¬
lated his problem will probably never be known, but some erroneous
statements can be corrected, and something can be done towards
establishing a limit to the time which elapsed. Whiston assigns the
cause of reworking the problem to an accidental turning over of his
early notes, but he mentions no date. Pemberton makes two mis¬
takes in his Preface to the Principia. He states that: “Some years af¬
ter, a letter which he received from Dr. Hooke put him on enquiring
what was the real figure, in which a body let fall from any high
place descends, taking the motion of the earth round its axis into
consideration.” The reader will remember that this letter was the
cause of Newton’s solving the general theorems of the attraction of
a sphere on a mass-point. This letter was written in 1679? as it is
evident, from the correspondence, that Newton was then acquainted
with the law of gravitation, he must have reworked his early calcu¬
lation before that time. “This gave occasion to his resuming his
former thoughts concerning the moon; and Picard in France having
lately measured the earth, by using his measures the moon appeared
to be kept in her orbit purely by the power of gravity.” This second
mistake was unfortunately adopted in the Biographia Britannica,
where it is explicitly stated that Picard’s measurement was published
in 1679.

Evidently Biot, in his Life of Newton , was misled by Pemberton’s
account into saying: “a ce que Ton peut conjecturer, vers le mois de
Juin 1682, se trouvant a Londres a une seance de la Societe Royale on
vint a parler de la nouvelle mesure d’un degre terrestre, recemment
execute en France par Picard.” He thus assigns the cause to New¬
ton’s first acquaintance with Picard’s work and places the date still

294

ISAAC NEWTON

later. Although Biot merely advanced this as a conjecture, it was
published in an English translation as a positive assertion, as if it were
founded on an investigation of the facts, and has been accepted as a
fact by popular writers who have failed to examine the sources.

An examination of any reference book on mathematics would
have shown the errors in the above statements about Picard. His
very accurate measurement of the earth was made in 1669 and pub¬
lished in his Mesure de la Terre in 1671. 4 Picard’s work was im¬
mediately recognised in England, and was referred to in the meet-
ing of the Royal Society, 11 January, 1671/2, when the exact length
of a degree, as he measured it, was specifically mentioned in a letter
read by the Secretary. At this same meeting, Newton was elected to
membership and his correspondence with Oldenburg began. The
matter aroused such interest that it was read again at the next meet-
ing. Three years later, in 1675, a detailed account was published in
Transactions, and it was again noticed the following year. In
this same year, Newton was present at a meeting for the first time on
the occasion of his being admitted a member and signing the register.
But during the years Picard’s work was discussed, Oldenburg had
been sending him regularly the Transactions, and giving to him in¬
formation about all matters of scientific interest. It thus seems cer¬
tain that he knew the correct diameter of the earth by 1675, the
latest. Nor does it seem credible that he had not recalculated his first
attempt when his attention was called to Picard’s work, even if he
had not done so before from the estimates of Snell, or Norwood.

It must be admitted that the argument, so far advanced, is some¬
what conjectural; but there is a bit of evidence, which has been
overlooked, and which should be convincing that Newton recalcu¬
lated the attraction of the moon not later than 1673. In that year
Huygens published his Horologium Oscillatorium and sent Newton
a complimentary copy. In this celebrated treatise, the author de¬
veloped, for the first time, the general laws for centrifugal force.

1 hat Newton read the book and recognised the bearing it had on the
problem of gravitation is certain, for he wrote to Oldenburg: “I
receiv’d your letters, with M. Huygens’s kind present, which I viewed
with great satisfaction, finding it full of very subtile and useful specu-

4 Marie in his Histoire des sciences remarks that Picard’s measurement “was sufficiently
aC< kr a k C / or Newton ’ ^ho awaited the results of this great operation before daring to
publish his discovery of the law of universal gravitation, to find by it a full confirmation
of his theory There is no doubt that Newton used Picard’s measurement in the prepara-
tion of the Pnncipta, but he certainly did not await the result before daring to publish
the law. In tact, Norwood’s measurement was accurate enough for that purpose.

THE PRINCIPIA

295

lations very worthy of the author. I am glad, that we are to expect
another discourse of the Vis Centrifuga, which speculation may prove
of good use in Natural Philosophy and Astronomy, as well as in
Mechanics.” 5

Newton also must have seen that Huygens’s law of centrifugal
force was easily deducible from his. own calculation on the attrac¬
tion of the moon, and that by neglecting to follow up his work,
Huygens had preceded him. This is proved from his statement in the
memorandum previously quoted: “What Mr. Huygens has published
since about centrifugal forces I suppose he had before me.” There
can be no reasonable doubt that Newton, at once, recognised that
Huygens had antedated him by the publication of one of the essen¬
tial deductions from his discovery of the law of gravitation, or that
he would not recollect his own early work with its faulty result, and
immediately recalculate it if he had not already done so? This time
there would be no question of neglecting to take a reliable figure,
such as Norwood’s or Picard’s, for the radius of the earth.

If Newton had satisfied himself fairly well in 1666 that he had
found the force which would account for Kepler’s planetary laws,
and did not fully satisfy himself till 1673, how can we account for
this delay? To suppose that it was because of taking a wrong
measure for the earth, does not fit with his character, for even a very
mediocre scientist could be expected to correct such a mistake. It
was the opinion of Professor Adams, that the result of his first rough
calculations would convince Newton that the moon was held in its
orbit by gravity alone, and he strongly suspected that Newton be¬
lieved then in a mutual attraction of the same sort between every two
particles of matter, which was proportional to the product of their
masses and inversely proportional to the square of the distance be¬
tween them. Great weight should be given to this opinion of Profes¬
sor Adams, not only because he was one of the greatest English

5 The original is in the guard-book (N. i) of the Royal Society and dated “June 23, 73.”
See Rigaud, p.. 44.

The law of centrifugal force developed by Huygens is f—v 2 /r, where / is the acceleration,
v is the linear velocity, and r is the distance from the centre. Newton, in making his recalcu¬
lation, could use either Huygens’s general formula, or the special one he had derived in his
earlier calculation. By Kepler’s third law, T 2 /r 3 is constant, where T is the periodic time

of the satellite. But v 2 =

4 % 2 r 2

and by substitution, f ==

4 % 2 r 2

Since T 2 is propor-

---Tf2 r

tional to r 3 , then f is proportional to 1/r 2 . Since the radius of the earth is approximately
4000 miles and the moon’s distance 240,000 miles, the relative accelerations are as the
squares of these distances. Newton’s first assumption of 60 statute miles, instead of 60
nautical miles, per degree of latitude corresponds to a radius of 3400 miles, about one-
eighth too small,

296

ISAAC NEWTON

astronomers but he was also the active member of the Cambridge
Committee which examined and catalogued Newton’s manuscripts.
The reason seems simple enough if we take into account his intense
activity in other work during that time. In mathematics, he had
made important discoveries in the solution of problems by the new
method of infinite series; he had edited Kinkhuysen’s Algebra, dis¬
covered the binomial theorem, and invented fluxional calculus. He
had accomplished an astonishing amount of work in the subject of
light; had prepared his course of Lucasian lectures, and had edited
Varenius’s Geography.

We may grant that Newton accomplished enough in those seven
years to satisfy a life-time of work; but still the question may be
asked, why did he postpone the problem of attraction which was the
most important of all his work? We should remember that he had
solved only an isolated problem approximately. It was contrary to
his custom to publish such incomplete discoveries; he meditated on
them till their full significance was revealed to him. He saw, at
once, if the earth and moon attracted each other at so great a dis¬
tance, then all bodies must possess a like force, and the applications
of such a universal property to problems of mechanics were almost
infinitely numerous.

Before such a generalisation could be made, a fundamental
theorem must be proved; that is, to find the effect of the size and
shape of the bodies on their attraction. Newton, in his early calcula¬
tions, had assumed the distance between the earth and moon to be so
great that he could neglect their own dimensions. But would the law
of the inverse square of the distance hold when the bodies were close
together, say for an apple on the tree, or on the ground ? What was
the law for bodies below the surface of the earth, and should the
distance be measured from the centres, or from the surfaces of the
bodies? Nor could it be assumed that the kind of material would
not affect the attraction and, sometime in his life, he performed many
experiments to prove that it did not. For this purpose he enclosed
successively different materials in a hollow pendulum bob and found,
to his great surprise, that the period of oscillation was unaffected.
All this information neither Newton nor anyone else had, and he was
too busy to acquire it.

In 1673, his attention was recalled to the subject by Huygens’s
formulation of the laws of centrifugal force, and he found that he
had been forestalled in one of the most important deductions of the

THE PRINCIPIA

297

law of gravitation. But, even then, he was not ready for his great
synthesis and, for six years more, the curtain conceals from us what
he was thinking about this problem. The curtain did not rise again
on this mystery drama till 1679, when Hooke wrote a civil letter to
Newton, asking him to communicate to the Royal Society any philo¬
sophical results he might come upon, and, particularly, to criticise M.
de Messanger’s new theory of the solar system. The correspondence
which ensued has been discussed in an earlier chapter. It will be re¬
membered Newton answered, that he had just returned from Lin¬
colnshire where he had been attending to family matters and had had
no time to think about philosophy. And as a further excuse he
added: “I had for some years past been endeavouring to bend myself
from philosophy to other studies in so much that I have long
grutched the time spent in that study unless it be perhaps at idle
hours sometimes for a diversion.” Then he, pleasantly, emphasized
his retirement from science by confessing that he is ignorant even of
Hooke’s great work. He is, he sarcastically adds, highly flattered to
be asked now to communicate new matters to the Royal Society
when “formerly I must acknowledge I was moved by other reasons
to decline, as much as Mr. Oldenburg’s importunity and ways to en¬
gage me in disputes would permit, all correspondence with him
about them.” As to his criticising the proposed cosmic theory, that
is quite impossible as there is no one in the University who makes
astronomical observations, “and my own short sightedness and ten¬
derness of health makes me something unfit.”

Newton thus, with great ingenuity, relieved his feeling of re¬
sentment for past injustice, and insinuated every reason for making
Hooke so angry that he would drop any further correspondence.
Having got even with his enemy, his better nature induced him, as
he later acknowledged to Halley, “to sweeten his answer” by adding
a fancy of his own which might, by observing the free fall of a body,
give a direct evidence of the earth’s diurnal rotation.

It will be remembered how greatly this fancy interested the Society,
and how Hooke, in his turn, took much pleasure in pointing out
publicly a careless error Newton had made in supposing the path of
the falling body would be a spiral. This fillip was useful and effec¬
tual, for Newton set himself seriously to the task of generalising the
problem of the moon. And, in the course of this work, he solved one
of the fundamental theorems of dynamics, that the attraction of a
body on a mass-point situated outside, on, or inside, the surface of

298

ISAAC NEWTON

the body was equivalent to the attraction of an equal mass placed at
its centre of gravity. The time was ripe, for other men were inter¬
ested in the problem. Thus, he wrote to Halley in 1686, “I remember
about nine years since Sir Christopher Wren, upon a visit Dr. Donne
and I gave him at his lodgings, discoursed of this problem of de¬
termining the planetary motions upon philosophical principle.” Poor
Hooke had the unfortunate habit of exasperating Newton to a de¬
gree which invariably aroused him to an effort that ended in crush¬
ing his own claims to discovery. In this case Hooke’s really im¬
portant, although inconclusive, work was swallowed up in the mas¬
terpiece which he incited his rival to create. Newton rather bitterly
acknowledged this fact: ‘'Though his correcting my spiral oc¬
casioned my finding the theorem, by which I afterwards examined
the ellipses; yet am I not beholden to him for any light into the busi¬
ness, but only for the diversion he gave me from my other studies
to think of these things, and for his dogmaticalness in writing.” 6
Pemberton 7 says that “hereupon he composed near a dozen proposi¬
tions relating to the motion of the primary planets about the sun.”
This may be an exaggeration as Newton, in a memorandum, stated
that he solved at that time only two of the important propositions
later included in the Pnncipia. Then this extraordinary man, ap¬
parently, dropped the subject and, except for his correspondence with
Flamsteed about the comet of 1680, he seems for five years to have
kept his word about giving his time to other matters he considered
more interesting.

When the curtain rises for the last act of the drama, the scene dis¬
covers three men in an inn discussing grave matters. Edmond Hal¬
ley, from consideration of the third law of Kepler, had come to the
conclusion that the centripetal force of attraction was inversely
proportional to the square of the distance. But, not being able to
prove it, he went up to London from Islington in January, 1683/4,
where he says: 8 “I met with Sir Christopher Wren and Mr. Hooke,
and falling in discourse about it, Mr. Hooke affirmed, that upon that
principle all the laws of the celestial motions were to be demon¬
strated, and that he himself had done it. I declared the ill success of
my own attempts; and Sir Christopher, to encourage the enquiry,
said, that he would give Mr. Hooke, or me, two months’ time, to
bring him a convincing demonstration thereof; and besides the hon¬
our, he of us, that did it, should have from him a present of a book

6 Rigaud, App. p. 44. 7 Cf. Preface to Princ. 3d Ed. 8 Rigaud. App. p. 36.

THE PRINCIPIA

299

of 40 shillings. Mr. Hooke then said, that he had it, but he would
conceal it for some time, that others trying and failing might know
how to value it, when he should make it public. However I re¬
member, that Sir Christopher was little satisfied that he could do it;
and though Mr. Hooker then promised to shew it him, I do not find,
that in that particular he has been so good as his word.”

Obtaining little satisfaction from his friends, the indefatigable
Halley probably went back to Islington to wrestle again with the
knotty problem. How much he was able to accomplish by himself
we do not know; but the following August he set out for Cambridge,
as he must have heard from Wren that Newton had talked about the
same subject with him some years back, and might be able to offer
some suggestions. Conduitt, although he is often not accurate, gives
a graphic picture of the interview which bears all the ear-marks of
the truth. Halley, he states, “at once indicated the object of his visit
by asking Newton what would be the curve described by the planets
on the supposition that gravity diminished as the square of the dis¬
tance. Newton immediately answered, an ellipse. Struck with joy
and amazement, Halley asked him how he knew it? Why, replied
he, I have calculated it; and being asked for the calculation, he could
not find it, but promised to send it to him.” 9 After Halley left Cam¬
bridge, “Sir Isaac, in order to make good his promise, fell to work
again, but he could not come to that conclusion which he thought he
had before examined with care; however, he attempted a new way,
which, though longer than the first, brought him again to his former
conclusion. Then he examined carefully what might be the reason
why the calculation he had undertaken before did not prove right,
and he found that, having drawn an ellipse cursorily with his
own hand, he had drawn the two axes of the curve, instead of draw¬
ing two diameters somewhat inclined to one another, whereby he
might have fixed his imagination to any two conjugate diameters
which was requisite he should do. That being perceived, he made
both his calculations agree together.” 10

One can easily imagine the conflicting emotions that must have
passed through Halley’s mind when he learned, at the same moment,
that Newton had solved the age-long problem of gravitation but
could not find his notes,—papers which other men would have re-

9 Conduitt’s MSS., Portsmouth Collection.

10 Mem. given to Conduitt by Demoivre. Portsmouth Collection .—This famous story of
Newton, being baffled by a simple error in drawing a diagram, is also given in Conduitt’s
MSS., but he mars it in his account.

3 00

ISAAC NEWTON

garded as their most precious possession. I think Halley must have,
then and there, penetrated the character of the man and realised the
task he was about to undertake. At any rate, he left Cambridge with
the hope that something large had been started; but he could not
have dreamed that he had laid the foundation for the Principia.
Newton’s powers were now thoroughly aroused. He set himself to
a second recalculation and found to his chagrin that he could not
carry it through. That great mind had been balked by a trivial error
which it pleases us to think could happen to him. He had carelessly
drawn two axes of an ellipse instead of two conjugate diameters,
and it was with difficulty that he found his mistake.

This last obstacle removed, Newton stayed in Cambridge the rest
of the summer and, at the opening of the Michaelmas term in
October, he had put into connected form enough problems on
planetary motion to serve for a course of nine lectures delivered un¬
der the title De Motu Corporum , n

These lectures thus form the nucleus of the Principia . Mindful
of his promise, Newton, in November, dispatched a copy of his
demonstrations to Halley by Paget, the ill-fated protege of Flam¬
steed. Halley had two characteristics in addition to his own ability,
a real flair for detecting distinction in others with the patience and
tact to bring out their best effort. He recognised at once the super¬
lative character of the work submitted to him. In order to waste no
time in a protracted correspondence, he, keen on the scent, travelled
at once to Cambridge to confer with the author, and to urge him
to send an abstract to the Royal Society so that his priority of dis¬
covery would be secured. It is probable also that the agreement was
made to expand these lectures into a treatise which would embrace
the applications of his discovery to the general problems of astron-

11 The lectures of Newton from Jan. 1669/70 to 1687 inclusive, with the exception of the
year 1686, have been preserved in the Cambridge University Library. They consist of four
manuscript volumes. The first volume contains his lectures on light from 1669 to 1672;
only the marginal notes and corrections are in his handwriting. The second volume com¬
prises lectures on arithmetic and algebra which he gave from 1673 to 1683.. The third
volume contains the lectures of 1684 and 1685 De Motu Corporum. The lectures for the
following year are either lost or were omitted. And the last volume is a series of five
lectures On the System of the World, which he delivered in 1687, and were intended for
the third book of the Principia. The remainder of the treatise, not divided into lectures, is
bound up in the same book. Newton delivered only one lecture a week during the
Michaelmas Term, making in all a course of nine or ten lectures a year. Each apparently
lasted a half hour and if, as sometimes happened, no one turned up, he lingered a short while
and then returned to his study. He also never repeated his lectures, but continued them
the following October where he had left off the preceding December. One may surmise that
his students, as Whiston confessed, understood but little of his discourses.

THE PRINCIPIA

3 01

omy. Satisfied by a promise given to him, he returned to London
and, on December io, 1684, presented the whole matter to the Royal
Society. Here, again, he succeeded: “Mr. Halley gave an account,
that he had lately seen Mr. Newton at Cambridge, who had shewed
him a curious treatise, De Motu; which, upon Mr. Halley’s desire,
was, he said, promised to be sent to the Society to be entered upon
their register. Mr. Halley was desired to put Mr. Newton in mind of
his promise for the securing his invention to himself till such time
as he would be at leisure to publish it. Mr. Paget was desired to
join with Mr. Halley.” 12 There is considerable doubt about the con¬
tents of this “curious treatise.” 13 However that may be, and it is a
rather unimportant detail, we know pretty conclusively how far he
had gone in his work by the end of the year.

Newton was now thoroughly committed again to publishing a
scientific work, in spite of the heartburnings and vexations which
that “litigious Lady” had previously imposed upon him. It is almost
certain that he did not foresee the magnitude of the work which he
had entered upon; at most, he expected to limit himself to the proof
of a law of force which would account for Kepler’s laws; to some
general geometrical theorems; and to their application to planetary
motions. He had resolved to expose these in the classic geometrical
form and to use the newer analytical geometry, and his own
method of fluxions, merely as an aid to their solution. The reason he
gave for this decision was that his ideas were novel and difficult to
understand in themselves, and he would have further increased the
labour of comprehending them, if he had used an unfamiliar math¬
ematical analysis. He also told his friend, the Rev. Dr. Derham, that
“to avoid being baited by little smatterers in mathematics, he designed¬
ly made his Principia abstruse; but yet so as to be understood by able
mathematicians who, he imagined, by comprehending his demon-

12 Birch, Vol. IV, p. 347.

13 Ball (p. 31) agrees with Rigaud (p. 15) that Halley saw in November the Mss. of
the lectures; that the tract De Motu was written the following December and January, and
sent to the Society as a record while the Principia, begun at the same time, was being written.
Edleston (p. Iv) believed “Rigaud’s idea that the paper which he has printed from the
Register of the Royal Society is different from the paper which Newton sent to Halley
was an error, as the whole tenor of our information on the subject shows them to be the
same.” Brewster (Vol. I, p. 299, note) supposes that the demonstration sent to Halley in
November was entered in the Register as part of the treatise De Motu .—Rigaud thought¬
fully rescued this tract from the oblivion of the Register and published it in the Appendix to
his Essay. It comprises four theorems and seven problems. He complained that the
copyist who transcribed the paper into the Register had been extraordinarily careless and
that he had much difficulty correcting it. Ball, since Rigaud’s work had become scarce,
inserted it in his own Essay.

302

ISAAC NEWTON

strations would concur with him in his theory.” 14 Already, in Feb¬
ruary, he had begun to realise the difficulty of the task and wrote
to Aston that the work was requiring more time than he expected,
and that he had wasted a great deal of it. Either for rest, or to at¬
tend to family affairs, he was leaving for home, but would finish the
manuscript as soon as he could, after his return in a month or six
weeks. 10 One might hazard the guess, that his worry and indecision
were not caused by inability to solve any particular problem, such a
predicament seems to have been unknown to him, but that he was
seeking for a general theorem which would include the whole cosmic
law. And may he not, as he did before, have found it during the
hours of inspiration which so often came to him at home ?

At any rate, he discovered and solved the general theorem of the
attraction of a solid sphere on a small mass soon after his return to
Cambridge. 16 He proved rigorously that the attraction between two
solid spheres was exactly equivalent to that of the same masses con¬
centrated at their centres, and was equal to the product of their
masses divided by the square of the distance between their centres.
Also, this same law holds for the attraction of a sphere on a mass
point situated on its surface; and if the point lies within the sphere
then the outer shell exerts no force, the resulting force being due
only to the smaller solid sphere whose radius passes through the
point. The significance of this theorem must have been immediately
apparent to him, and we can imagine his profound satisfaction and
exaltation of mind when he thus realised that to him had been given
the solution of the age-long problem which had baffled the greatest
minds of the past. He had found the force which would account for,
and measure, the cohesion of a universe scattered through the vast
distances of space; a force which would not vanish until the distance
became infinite, and would not become infinite unless two bodies
occupied the same point in space. All the doubts which had hitherto
disturbed him were now settled. There was no longer any question
as to the direction of the force between two bodies, or whether the
law extended to the surface or the centre of the earth. He knew
now that the path of every orbital motion is an ellipse; that even the
comets submitted to this law though, when near the sun, the ellipse
might be considered as approximately an hyperbola or a parabola;

14 Portsmouth Collection. 15 See letter to Aston, supra Chapter VII, p. 245.

16 His exits and redits for 1685 show that he was away from Cambridge from March
27 to April 11 and from June 11 to June 20. I cannot reconcile these entries with his
letter to Aston.

THE PRINCIPIA

303

and that the path of a projectile could be described as a parabola
only because the surface of the earth was assumed to be an infinite
plane instead of a sphere.

Newton now threw himself into the greater task of elaborating a
cosmic system developed according to rigorous mathematical formu¬
lation, and dependent only on his general law of attraction. We
learn of his profound absorption; he lived in a world of meditation.
His amanuensis, Humphrey Newton, has left us the impression that
he hardly seemed to be a human being, his only relaxation an oc¬
casional retreat to his chemical laboratory, and even there he may
have been seeking for the principle of chemical affinity by the attrac¬
tion of corpuscles. And there are legends that he was not conscious
of whether he had eaten his meals or not, and that, rising in the
morning, he would remain all day sitting on his bed half dressed
and lost in thought. We must remember that the Principia was not
developed from comprehensive notes and data, but was created, de
novo, step by step. And yet by Easter, 1685, the manuscript of the
first book, except for some corrections and additions, was finished;
and, during the summer, the second book was composed in rough
form. It is probable, also, that he worked out some of the applica¬
tions of his law, which he later incorporated in the third book. At
least, he turned to Flamsteed for astronomical data in four letters
written between September and the following January. He stated in
them that he was calculating the orbit of the comet of 1680 from three
observations. He also asked for information about the tides, about
the major axes of the orbits of Jupiter, Saturn, and their satellites,
and expressed his thanks for the information received. When the
Michaelmas term began, he gave a course of ten lectures, continuing
the subject De Motu where he had left off the preceding year.

The whole of the year 1686 was passed in Cambridge. We may be
certain that Halley kept in close touch with the progress of the work;
in fact, he continued to work on the subject himself for, at the meet¬
ing of the Society on April 21, he “read a discourse of his own, de¬
signed for a Philosophical Transaction, concerning the cause and
properties of gravity wherein he considers the several hypotheses
concerning its impulses, and then mathematically deduces its conse¬
quences in the fall of heavy bodies, and the motion of projects
[projectiles].” 17 At the next meeting, a week later, the memorable
note was entered: “Dr. Vincent presented to the Society a manu-

17 This discourse was published in the Phil. Trans , No. 179, p. 3.—Birch, Vol. IV, p. 479.

304

ISAAC NEWTON

script entitled, Philosophiae Naturalis principia mathematica, and
dedicated to the society by Mr. Isaac Newton, wherein he gives a
mathematical demonstration of the Copernican hypothesis as pro¬
posed by Kepler, and makes out all the phenomena of the celestial
motions by the only supposition of a gravitation towards the centre
of the sun decreasing as the squares of the distances therefrom
reciprocally. It was ordered, that a letter of thanks be written to
Mr. Newton; and that the printing of this book be referred to the
consideration of the council; and that in the meantime the book be
put into the hands of Mr. Halley, to make a report thereof to the
council.” 18

This Dr. Vincent, who had the honour to present the manuscript,
has been erroneously identified with the husband of Newton’s early
fiancee, Miss Storey. It is sufficient to point out that he was a bach¬
elor, since he was, at that time, Senior Fellow of Clare College, and
continued so until his death. The following incident in his life has
been recorded by Whiston 19 which sheds an interesting light on the
history and the superstition of the time. He states, that he went with
Dr. Nathaniel Vincent, into Norfolk, towards the end of May, 1687
or 1688, and found that the Doctor was expected to preach a sermon
on the Solemnity for the Restoration, at the Cathedral of Norwich.
He was known to be a great friend of King James, and Whiston
thought he hoped by flattering the King to be made a Bishop at the
very time when the Protestants and the University were in great
dread of Popery. However, he had no suitable sermon at hand but,
from some notes and with the aid of Whiston as amanuensis, he pre¬
pared one which his young assistant thought to be no better than
were most of such court-sermons. Later, when the Prince of Orange
came to the country’s deliverance, the Cambridge mob got up and
amongst other actions threatened Dr. Vincent. Frightened by this
demonstration, he decided to leave college for a while. He accord¬
ingly called on Whiston, who was his Sizar, to assist him in prepar¬
ing for his Removal . It seems that his Sizar spilled his salt that night
at supper, and the learned Doctor exclaimed very solemnly: “It
would be a sad completion of this omen if they should find him dead
in his bed the next morning.” Whiston caustically remarks that the
Doctor lived a great many years after the omen.

The Council of the Royal Society did not act for some weeks,

i8 Birch, Vol. IV, p. 479. 19 Whiston, Memoirs, pp. 21-24.

THE PRINCIPIA

3°5

apparently because the president, Samuel Pepys, was in attendance
on King James on affairs of the navy, and the vice-presidents were
all out of town because of the fine weather. But at the meeting of
May 19, Sir Joseph Williamson, vice-president in the chair, it was
ordered “that Mr. Newton’s Philosophiae naturcdis principia mathe-
matica be printed forthwith in quarto in a fair letter; and that a
letter be written to him to signify the Society’s resolution, and to de¬
sire his opinion as to the print, volume, cuts, etc.” 20 The record, as
usual, is quite colourless, but there had evidently been a somewhat
acrimonious discussion during which the irrepressible Hooke again
claimed that Newton had been greatly aided in the discovery of the
law of gravitation by his own work, and that he expected a suitable
acknowledgement to be made in the published work. How tactfully
Halley managed this contretemps, and soothed the irritated author,
almost as if he had been an unreasonable child, can be gathered
from the correspondence which passed between them. Worried, lest
an exaggerated rumour of this unfortunate incident should reach
Newton’s ears, Halley wrote him the following letter on May 22:

Halley to Newton
Sir,

Your incomparable treatise, entitled, Philosophiae naturalis princi¬
pia mathematica, was by Dr. Vincent presented to the Royal Society
on the 28th past; and they were so very sensible of the great honour
you have done them by your dedication, that they immediately
ordered you their most hearty thanks, and that the council should be
summoned to consider about the printing thereof. But by reason of
the president’s attendance upon the king, and the absence of our
vice-presidents, whom the good weather has drawn out of town,
there has not since been any authentic council to resolve what to do
in the matter, so that on Wednesday last the Society in their meeting
judging, that so excellent a work ought not to have its publication
any longer delayed, resolved to print it at their own charge in a large
quarto of a fair letter; and that this their resolution should be sig¬
nified to you and your opinion thereon be desired, that so it might be
gone about with all speed. I am entrusted to look after the printing
of it, and will take care, that it shall be performed as well as possible.
Only I would first have your directions in what you shall think
necessary for the embellishing thereof, and particularly whether you

20 Birch, VoL IV, p. 484.

ISAAC NEWTON

3°6

think it not better, that the schemes should be enlarged, which is the
opinion of some here: but what you signify as your desire shall be
punctually observed.

There is one thing more, that I ought to inform you of, viz. that
Mr. Hooke has some pretensions upon the invention of the rule of
decrease of gravity being reciprocally as the squares of the distances
from the centre. He says you had the notion from him, though he
owns the demonstration of the curves generated thereby to be wholly
your own. How much of this is so, you know best; as likewise what
you have to do in this matter. Only Mr. Hooke seems to expect you
should make some mention of him in the preface, which it is pos¬
sible you may see reason to prefix. I must beg your pardon, that it
is I, that send you this ungrateful account; but I thought it my duty
to let you know it, that so you might act accordingly, being in my¬
self full satisfied, that nothing but the greatest candour imaginable
is to be expected from a person, who has of all men the least need to
borrow reputation. I am, etc. 21

Newton replied at once to Halley:

Newton to Halley

I thank you for what you write concerning Mr. Hooke, for I desire
that a good understanding may be kept between us. In the papers in
your hands there is not one proposition to which he can pretend, and
so I had no proper occasion of mentioning him there. In those be¬
hind where I state the system of the world I mention him and others.
But now we are upon this business, I desire it may be understood.
The sum of what past between Mr. Hooke and me (to the best of my
remembrance) was this. He soliciting me for some philosophical
communications or other I sent him this notion, that a falling body
ought by reason of the earth’s diurnal motion to advance eastward
and not fall to the west as the vulgar opinion is. And in the scheme
wherein I explained this I carelessly described the descent of the fall-

21 Birch, Vol. IV, p. 484. ... Of the seventeen (or more) letters which passed between
Halley and Newton in 1686-7, sixteen are extant. Ball has reprinted them in his Essay
as an Appendix. I have referred to these letters and given some extracts from them in a
previous chapter in order to explain the incidents of the year 1679. At the risk of being
tedious, I am giving here all the parts of the letters which are of more than passing interest
as they are important in revealing Newton’s character. I have also in foot-notes given
the reference to their first publication. If the reader desires all the details of this controversy
with Hooke and minute points about the Principia, he may refer to Ball’s Essay, p. 153
et seq.

THE PRINCIPIA

3°7

ing body in a spiral to the centre of the earth: which is true in a re¬
sisting medium, such as our air is. Mr. Hooke replied, it would not
descend to the centre but at a certain limit return upwards again. I
then took the simplest case for computation, which was that of
gravity uniform in a medium not resisting—imagining he had
learned the limit from some computation, and for that end had con¬
sidered the simplest case first. And in this case I granted what he
contended for, and stated the limit as nearly as I could. He replied
that gravity was not uniform but increased in descent to the centre
in a reciprocal duplicate proportion of the distance from it, and thus
the limit would be otherwise than I had stated it, namely, at the end
of every entire revolution, and added that according to this dupli¬
cate proportion the motions of the planets might be explained and
their orbs defined. This is the sum of what I remember. If there
was anything more material or any thing otherwise I desire Mr.
Hooke would help my memory. Further that I remember about 9
years since Sir Christopher Wren, upon a visit Dr. Donne and I
gave him at his lodgings, discoursed of this problem of determining
the planetary motions upon philosophical principles. This was about
a year or two before I received Mr. Hooke’s letters. You are ac¬
quainted with Sir Christopher. Pray know where and whence he
first learnt the decrease of the force in a duplicate ratio of the distance
from the centre.

Sir, I am your most affectionate and humble servant.

I. N. 22

Halley had not only the delicate task of managing the irritability
of the author, but he also found that he could not depend on the
Society for funds to publish the treatise. The record of June 2 states
briefly: “It was ordered, that Mr. Newton’s book be printed, and
that Mr. Halley undertake the business of looking after it, and
printing it at his own charge; which he engaged to do.” 23 In this
emergency, when he saw his hopes about to be frustrated, Halley de¬
termined to pay the costs himself. It was no slight burden. He had
been brought up to no profession as his father had been a rich man.
But, on the death of his father, he found himself reduced to com¬
parative poverty and with a wife and young children to support. In
this state of his affairs, he had been glad to accept the position as
assistant to the secretaries of the Society at a stipend of ^50. The

22 Ball, p. 155. 23 Birch, Vol. IV, p. 486.

ISAAC NEWTON

3°8

Society has been severely, and even bitterly, criticised for not secur¬
ing to itself the credit of financing so great a work, but there were
extenuating circumstances. The vote at the general meeting of May
19 was of no force in itself, since it required the expenditure of
money and, by the statutes, no sum exceeding £5 could be paid ex¬
cept on order from Council. Now the Council knew that the Society
was practically bankrupt, and it is difficult to see how they could
legally authorise any additional obligation. In previous emergencies
of this sort, they had been accustomed to depend on the generosity of
individual members and, in this case, Halley evidently offered to re¬
lieve them of their embarrassment. The Society had rashly published
Willughby’s De Historia Piscium in an edition of 500 copies at a cost
of ,£400. I n addition to this large sum, Pepys had subscribed £50
towards the publication, and had provided for eighty of the plates,
and other members had also contributed. The Society was also con¬
fronted with the problem of collecting unpaid dues. The situation
had become so bad that the Council on July 22, 1685, ordered forty-
seven names to be stricken from the roll unless they paid their ar¬
rears; amongst them, were many of the richest noblemen of the
country, and also John Locke. Salaries were unpaid, and Halley and
Hooke were asked to accept pay in the form of a number of copies
of Willughby’s book which had a very slow sale. As late as 1740, as
many as 125 sets were still unsold and the Society, to meet its ex¬
penses, had to sell some of its securities in the India stock. It is re¬
ported that the generous Halley accepted this proposition; but the
careful Hooke desired six months to consider it. It thus seems that
criticism for this action might properly be directed against wealthy
members rather than against the Society. Even so, we do not know
the circumstances, and Halley may have claimed the right to be the
sponsor, esteeming it an honour worth serious financial embarrass¬
ment. Somehow, opinion seems to have overlooked the duty of
Newton, who was by no means poor, to contribute to part at least of
the expense of the publication of his own work. His attitude is cer¬
tainly a most curious one, as he seemed to take no more interest, or
pride, in it than the proverbial stepfather, and was quite willing to
accept the charity of one who was almost a stranger.

As soon as this agreement was reached, Halley prepared vigorous¬
ly to see the work through the press. On June 7, he could write that
the first book was in press.

THE PRINCIPIA

309

Halley to Newton

London, June 7, 1686.

I here send you a proof of the first sheet of your book, which we
think to print on this paper, and in this character; if you have any
objection, it shall be altered: and if you approve it, we will proceed;
and care shall be taken that it shall not be published before the end
of Michaelmas term, since you desire it. I hope you will please to be¬
stow the second part, or what remains of this, upon us as soon as you
shall have finished it, for the application of this mathematical part
to the system of the world, is what will render it acceptable to all
naturalists, as well as mathematicians; and much advance the sale
of the book. Pray, please to revise this proof, and send it me up with
your answer. I have already corrected it, but cannot say I have spied
all the faults. When it has past your eye, I doubt not but it will be
clear from errata. The printer begs your excuse of the diphthongs,
which are of a character a little bigger, but he has some a casting of
the just size. This sheet being a proof is not so clear as it ought to
be; but the letter is new, and I have seen a book of a very fair char¬
acter, which was the last thing printed from this set of letter; so that
I hope the edition may in that particular be to your satisfaction. I
3.1x1 Sr

’ * Your most affectionate humble servt,

E. Halley . 24

The progress of the book to its completion, as well as the difficul¬
ties which Halley had to overcome, is told in the correspondence be¬
tween the two. Newton was much exasperated by Hooke’s new
claim and, in his reply to Halley, he explained very forcibly that the
claim was unjust. His letter of June 20 25 is too long to give in full,
and the quarrel becomes somewhat wearisome. The following ex¬
tracts, however, are important:

“The proof you sent me I like very well. I designed the whole to
consist of three books; the second was finished last summer being
short, and only wants transcribing, and drawing the cuts fairly.
Some new propositions I have since thought on, which I can as well
let alone. The third wants the theory of comets. In autumn last I
spent two months in calculations to no purpose for want of a good

24 Ball, p. 156. 25 Ball, p. 156.

3 10

ISAAC NEWTON

method, which made me afterwards return to the first book, and en¬
large it with divers propositions, some relating to comets, others to
other things, found out last winter. The third I now design to sup¬
press. Philosophy is such an impertinently litigious Lady, that a man
had as good be engaged in lawsuits, as have to do with her. I found
it so formerly, and now I am no sooner come near her again, but she
gives me warning. The two first books, without the third, will not
so well bear the title of Philosophiae Naturalis Principia Mathe¬
matic a; and therefore I had altered it to this, De Motu Corporum
libri duo. But, upon second thoughts, I retain the former title.
’Twill help the sale of the book, which I ought not to diminish
now ’tis yours. The articles are, with the largest, to be called by that
name; if you please you may change the word to sections, though it
be not material. . . . [Postscript] Since my writing this letter, I am
told by one, who had it from another lately present at one of your
meetings, how that Mr. Hooke should there make a great stir, pre¬
tending that I had all from him, and desiring they would see that
he had justice done him. This carriage towards me is very strange
and undeserved; so that I cannot forbear, in stating the point of
justice, to tell you further, that he has published Borell’s hypothesis
in his own name....

“Mr. Hooke has erred in the invention he pretends to, and his
error is the cause of all the stir he makes. For his extending the
duplicate proportion down to the centre (which I do not) made
him correct me, and tell me the rest of his theory as a new thing to
me, and now stand upon it, that I had all from that his letter, not¬
withstanding that he had told it to all the world before, and I had
seen it in his printed books, all but the proportion. And why should
I record a man for an invention, who founds his claim upon an error
therein, and on that score gives me trouble? He imagines he
obliged me by telling me his theory, but I thought myself disobliged
by being, upon his own mistake, corrected magisterially, and taught
a theory, which every body knew, and I had a truer notion of than
himself. Should a man who thinks himself knowing, and loves to
show it in correcting and instructing others, come to you, when you
are busy, and notwithstanding your excuse press discourses upon you,
and through his own mistakes correct you, and multiply discourses;
and then make this use of it, to boast that he taught you all he
spake, and oblige you to acknowledge it, and cry out injury and in¬
justice if you do not; I believe you would think him a man of

THE PRINCIPIA

3™

strange unsociable temper. Mr. Hooke’s letters in several respects
abounded too much with that humour, which Hevelius and others
complain of; and therefore he may do well in time to consider,
whether, after this new provocation- I be much more bound (in do¬
ing him that justice he claims) to make an honourable mention of
him in print, especially since this is the third time that he has given
me trouble in this kind.” .. .

In spite of the careful wording of Halley’s report about Hooke,
Newton was aroused to make a detailed repudiation of the claims;
and when he learned later from some one, who had heard the news
from another who had been present, that Hooke had made “a great
stir,” he added a scathing rebuke and a justification of his own
work. No one could blame him for being thoroughly angry. But
one can not excuse him for his decision—to suppress the third book
simply because one man, with a mind diseased by jealousy and
vanity, had foolishly made a scene. What manner of a man was
Newton, who could thus contemptuously cast off his own intellectual
child; there is certainly no parallel to the incident in all history.
Did any other man ever show a deeper jealousy and vanity than New¬
ton, who could let the personal criticism of another, and a slight re¬
flection on his own character, outweigh the work of his life and the
fruit of his genius? Since the book, thus mutilated, would be greatly
restricted in its scope and value, he decided to change the title of
System of the World to the colourless one of On the Motion of
Bodies . Then it occurred to him that Halley had a financial interest
in the book, however unimportant it might be to himself, so he de¬
cided to retain the catch-sale title even though it were misleading
because, forsooth, “ ’Twill help the sale of the book, which I ought
not to diminish now ’tis yours.” This incident, I confess, shocks me.
It is not inspiring to see a work of genius carelessly chaffered as
might be a second-hand piece of furniture, even if the advantage be
ostensibly sought for a friend’s purse. If gratitude had really been
the motive it would have shone with a brighter lustre if he had re¬
fused to let his personal annoyance overweigh his duty to make
public his work.

One can imagine what a thunderbolt such a piece of news was to
Halley, for the third book was the flower of the whole work, and
without it the treatise would be like Hamlet with Hamlet left out.
In this frame of mind he wrote the following diplomatic letter:

312

ISAAC NEWTON

Halley to Newton
Sr,

I am heartily sorry, that in this matter, wherein all mankind ought
to acknowledge their obligations to you, you should meet with any¬
thing that should give you disquiet, or that any disgust should make
you think of desisting in your pretensions to a Lady, whose favours
you have so much reason to boast of. Tis not she, but your rivals
envying your happiness that endeavour to disturb your quiet enjoy¬
ment, which when you consider, I hope you will see cause to alter
your former resolution of suppressing your third book, there being
nothing which you can have compiled therein, which the learned
world will not be concerned to have concealed. Those gentlemen of
the Society, to whom I have communicated it, are very much
troubled at it, and that this unlucky business should have happened
to give you trouble, having a just sentiment of the author thereof.
According to your desire in your former, I waited upon Sr Chris¬
topher Wren, to enquire of him, if he had the first notion of the
reciprocal duplicate proportion from Mr. Hooke, his answer was,
that he himself very many years since had had his thoughts upon
the making out the planets’ motions by a composition of a descent
towards the sun, and an imprest motion; but that at length he gave
over, not finding the means of doing it. Since which time Mr.
Hooke had frequently told him that he had done it, and attempted
to make it out to him, but that he never satisfied him that his demon¬
strations were cogent. . . .

As to the manner of Mr. Hooke’s claiming this discovery, I fear it
has been represented in worse colours than it ought; for he neither
made public application to the Society for justice, nor pretended you
had all from him. The truth is this. Sr John Hoskins, his particular
frie[n]d being in the chair, when Dr. Vincent presented your book,
the Dr. gave it its just encomium, both as to the novelty and dignity
of the subject. It was replied by another gentleman that you had car¬
ried the thing so far that there was no more to be added. To which
the Vice-President replied, that it was so much the more to be prized,
for that it was both invented and perfected at the same time. This
gave Mr. Hooke offence, that Sr. John did not, at that time, make
mention of what he had, as he said, discovered to him; upon which
they two, who till then were the most inseparable cronies, have since
scarce seen one another, and are utterly fallen out. After the break-

THE PRINCIPIA

313

ing up of that meeting, being adjourned to the coffee-house, Mr.
Hooke did there endeavour to gain belief, that he had some such
thing by him, and that he gave you the first hint of this invention.
But I found, that they were all of opinion, that nothing thereof ap¬
pearing in print, nor on the books of the Society, you ought to be con¬
sidered as the inventor. And if in truth he knew it before you, he
ought not to blame any but himself, for having taken no more
care to secure a discovery, which he puts so much value on. What ap¬
plication he has made in private, I know not, but I am sure that the
Society have a very great satisfaction in the honour you do them, by
your dedication of so worthy a treatise. Sr, I must now again beg
you, not to let your resentments run so high, as to deprive us of your
third book, wherein the application of your mathematical doctrine to
the theory of comets and several curious experiments, which, as I
guess by what you write, ought to compose it, will undoubtedly
render it acceptable to those, that will call themselves philosophers
without mathematics, which are by much the greater number. Now
you approve of the character and paper, I will push on the edition
vigorously. I have sometimes had thoughts of having the cuts neatly
done in wood, so as to stand in the page, with the demonstrations,
it will be more convenient, and not much more charge. If it please
you to have it so, I will try how well it can be done; otherwise I will
have them in somewhat a larger size than those you have sent up.

I am, Sr, Your most affectionate humble servt,

London, 29 June, 1686. ^ ALLEY *

To Mr. Isaac Newton in Trinity Colledg. Cambridg.

On the last day of June, the President was desired to license the
publication and, five days later, Pepys put his name to the imprima¬
tur. In the meanwhile, Halley’s letter had calmed the troubled
waters, and had awakened the better nature of Newton. And when
that occurred he usually acknowledged his fault, and apologised with
sincerity and humility. Thus, he wrote to Halley: 27 “I am very
sensible of the great kindness of the gentlemen of your Society to me,
far beyond what I could ever expect or deserve, and know how to
distinguish between their favour and another’s humour. Now I

26 Ball, pp. 162-164.—The argument of Newton and Halley, that Hooke had no just claim
to the discovery because he had not published it, should be recollected when the controversy
with Leibniz is discussed. Newton’s case was then, what Hooke’s is in this incident.

27 Ball, p. 165.

3i4

ISAAC NEWTON

understand he was in some respects misrepresented to me, I wish I
had spared the postscript to my last.” He then states what had been
reported to him about Hooke, and closes the letter by agreeing to
make a reference to him in the book: “And now having sincerely
told you the case between Mr. Hooke and me, I hope I shall be free
for the future from the prejudice of his letters. I have considered
how best to compose the present dispute, and I think it may be done
by the enclosed scholium to the fourth proposition.” Thus, this mat¬
ter was dropped, and he agreed to go on with the whole work as
originally planned.

Newton spent the remainder of the summer in Cambridge, re¬
vising the manuscript of the second book, and working on the ap¬
plications of his law to the motions of satellites, comets, and other
cosmic problems. When College opened in the autumn, he gave his
course of lectures, continuing his exposition De Motu . At the same
time, the second book was completed and made ready for the press;
but he retained the manuscript, as he thought that the printer would
not be ready for it till November or December. In fact, it was not
until March i, 1686/7, that he wrote to Halley. “You’ll receive
the 2nd book on Thursday night or Friday by the coach. I have di¬
rected it to be left with Mr. Hunt at Gresham Coll. Pray let me beg
the favour of a line or two to know of the receipt. I am obliged to
you for pushing on the edition, because of the people’s expectation,
tho’ otherwise I could be as well satisfied to let it rest a year or two
longer. ’Tis a double favour, that you are pleased to double your
pains about it.” This is another instance which must be left to a
guess; whether he found that the book had been written too hurried¬
ly, or whether it was another case of his characteristic procrastina¬
tion.

In the meanwhile, there had been trouble and delay with the
printer. Six months had been wasted before even a start had been
made, and Halley gave the second book to another firm in order that
both books should appear at the same time. He, also, threatened to
give the third book to yet another firm, but finally sent it to the
original printer on his promise that it would be worked on diligently.
The third book, with the title De Systemate Mundi, required a large
amount of astronomical data, and Newton was most fortunate in
being able to obtain the assistance of Flamsteed; it is also believed
that Halley aided him with data and calculations. The manuscript
was finally sent up to London early in April.

THE PRINCIPIA

3*5

The satisfaction of Halley is readily understood when he finally
held the complete copy in his hands and realised that his laborious
task was come to an end.

Halley to Newton

Honoured Sr, London ’ A P ril 5 - i68 7 '

I received not the last part of your divine Treatise till yesterday,
though it came to town that day sennight; having had occasion to
be out of town the last week. The first part will be finished within
this three weeks, and considering the shortness of the third over the
second, the same press that did the first will get it done so soon as
the second can be finished by another press; but I find some difficulty
to match the letter justly. . . .

I do not find that you have touched that notable appearance of
comets’ tails, and their opposition to the sun which seems rather to
argue an efflux from the sun than a gravitation towards him. I doubt
not but this may follow from your principles with the like ease as all
the other phenomena; but a proposition or two concerning these
will add much to the beauty and perfection of your theory of comets.
I find I shall not get the whole completed before Trinity term, when
I hope to have it published; when the world will not be more in¬
structed by the demonstrative doctrine thereof, than it will pride
itself to have a subject capable of penetrating so far into the ab-
strusest secrets of nature, and exalting human reason to so sublime a
pitch by this utmost effort of the mind. But least my affection should
make me transgress, I remain,

Your most obedient servant,

Edm. Halley . 28

On the next day, he presented the manuscript to the Society: “The
third book of Mr. Newton’s treatise De Systemate Mundi was pro¬
duced and presented to the Society. It contained the whole system
of celestial motions, as well of the secondary as primary planets, with
the theory of comets; which he illustrated by the example of the
great comet of 1680/1, proving that, which appeared in the morn¬
ing in the month of November preceding, to have been the same
comet, that was observed in December and January in the eve-

28 Ball, p. 173.

ISAAC NEWTON

3 i 6

ning.” 29 The earlier authorities, such as Weld in his History of the
Royal Society, state that the manuscript, “entirely written by New¬
ton’s own hand,” is preserved in the museum of the Society and is
esteemed its most precious treasure. Edleston, however, leaves little
doubt that this manuscript is in the same hand as the first draught
of the Principia in the University Library. Both manuscripts have
corrections and additions which are undoubtedly in the author’s
own hand. In support of this opinion, we have the statement of
Humphrey Newton, that he copied the whole manuscript, and one
would suppose that as an amanuensis he had been engaged for that
purpose.

The reader, when he peruses the last letter written on the publi¬
cation of the Principia, will share the feelings of Halley and regard
him as a rare spirit:

Halley to Newton

Honoured Sr, London > ^ 5. 1687.

I have at length brought your book to an end, and hope it will
please you. The last errata came just in time to be inserted. I will
present from you the books you desire to the R. Society, Mr. Boyle,
Mr. Paget, Mr. Flamsteed, and if there be any else in town that you
design to gratify that way; and I have sent you to bestow on your
friends in the University 20 copies, which I entreat you to accept.
In the same parcel you will receive 40 more, which, having no ac¬
quaintance in Cambridge, I must entreat you to put into the hands
of one or more of your ablest booksellers to dispose of them: I intend
the price of them bound in calves’ leather and lettered, to be 9 shil¬
lings here. Those I send you I value in quires at 6 shillings, to take
my money as they are sold, or at 5 sh a price certain for ready, or else
at some short time; for I am satisfied that there is no dealing in
books without interesting the booksellers, and I am contented to let
them go halves with me, rather than have your excellent work
smothered by their combinations. I hope you will not repent you of
the pains you have taken in so laudable a piece, so much to your own
and the nation’s credit, but rather, after you shall have a little di¬
verted yourself with other studies, that you will resume those con¬
templations, wherein you have had so good success, and attempt the

29 Birch, IV, p. 529. It is here that Newton could gracefully have expressed his obligation
to Flamsteed for pointing out his former erroneous belief about the comet.

THE PRINCIPIA

3*7

perfection of the lunar theory, which will be of prodigious use in
navigation, as well as of profound and subtile speculation. Sr. I shall
be glad to hear that you have received the books, and to know what
farther presents you would make in town which shall be accordingly
done. You will receive a box from me on Thursday next by the
wagon, that parts from hence to-morrow. I am Your most obliged

humble servt, Edm. Halley . 30

To Mr. Isaac Newton,

In Trinity Colledg. Cambridg. These.

About midsummer, 1687, the Principia was finally published dur¬
ing the presidency of the Earl of Carbery. This edition was very
small and sold probably for ten or twelve shillings a copy. Rather
to the surprise, I think, of Halley, the edition sold quickly and, by
1691, it was very difficult to obtain a copy. Halley, in addition to all
his other services, prefixed a graceful tribute to the author in a set
of verses in Latin hexameters; and he also presented a copy to King
James II, accompanied by a paper, explaining the purpose and ac¬
complishment of the book, together with a flattering compliment to
His Majesty. There was even a promise offered to explain the more
difficult parts to the royal mind; but, I daresay, a James II would not
be apt to discover the humour in such a suggestion. It seems likely
that Halley did not lose a great deal financially.

So ends the history of the preparation of this remarkable book,—
remarkable in its content, remarkable in that it was written in
seventeen or eighteen months, and remarkable in its mode of pub¬
lication. But the most inexplicable feature of the book was the atti¬
tude of the author towards his own progeny. He apparently took
little interest in what he once mentioned to Halley as “your book.”
The text was cast in a strictly classical and geometrical form, which is
not suitable to problems of motion, although he had discovered in
his method of fluxions one admirably adapted to his needs. He made
no concessions to his readers and he seemed to have had in mind a
few, perhaps Halley and one or two others, whom he addressed
personally, and to have been indifferent to all the rest of the world.
In truth, few could read it then, and few have ever read it except
under compulsion of the schools. For example, Demoivre, himself
no mean mathematician, was by chance at the Duke of Devonshire’s
when Newton called to present a copy to the Duke. The young

30 Ball, pp, 173-4.

3i8

ISAAC NEWTON

mathematician opened the book and, misled by its apparent sim¬
plicity, thought he could master it without any difficulty. He soon
found it was beyond his comprehension and that he had a long, and
thorny, road to travel before he could understand it. But he bought a
copy, which he tore into sheets so that he could carry a small portion
in his pocket and study it in the intervals of his other work. Yet men
like John Locke and Richard Bentley, who were not mathematicians,
were fascinated by its philosophy. And the latter asked Newton to
suggest a course of study which would prepare him to understand it.
He received such a portentous list that he gave up the project lest the
preparation would require the better part of his life. But he did by
correspondence obtain enough insight into the author’s philosophy to
use it as an argument for the confutation of atheism in his famous
Boyle sermons. The concluding lecture of the series was devoted to
the purpose of proving the necessity of a Divine Providence, be¬
cause of the orderliness in the laws of nature as demonstrated in the
Principia.

Gregory of Scotland became an enthusiastic Newtonian, and the
Universities of St. Andrews and Edinburgh were probably the first
in Britain to teach his ideas. At Oxford, the displacement of the
Aristotelian and Cartesian schools was slow, although David Greg¬
ory moved to that University in 1690, and Whiston laments that “he
had already caused several of his scholars to keep Acts, as we call
them, upon several branches of the Newtonian philosophy; while we
at Cambridge, poor wretches, were ignominiously studying the ficti¬
tious hypotheses of the Cartesian.” In the same passage, he also
states that he heard Newton read one or two of his lectures though
he did not then understand them. Laughton, tutor of Clare Col¬
lege and Senior Proctor, has the honour of having been the first in
Cambridge to introduce the Newtonian philosophy, “for by choosing
the Principia of Newton as the predominant subject both of the ex¬
ercises in the schools and the mathematical examination for degrees,
he enforced among the students the general attention to that im¬
mortal work, which has from his time never ceased to distinguish
the University of Cambridge.” 31 We must remember also that New¬
ton, himself, lectured on the new mechanics till he left Cambridge

^ 1 Monk s Life of Bentley, Vol. I, p. 288.—The bishop gives an absurd story about
Laughton who performed his proctorial duties with more zeal and rigour than discretion.
On one occasion, the parliamentary representatives were entertaining a select party of
their constituents at the Rose Tavern. About ten o’clock, the Proctor, preceded by a lictor,
and followed by a number of undergraduates as his bodyguard, burst into the room and

THE PRINCIPIA

319

although Edleston does not list his subjects or discourses. While
there were individual converts, the general introduction of his philos¬
ophy was slow; it was Lord Mansfield’s opinion, made during a legal
argument, that the works of Milton, Locke, and Newton suffered
for a considerable time before they were properly appreciated.

The appreciation of the Principia was even slower outside Eng¬
land. A few scholars, like Leibniz and Huygens, were keen to have
a sight of the work, but it attracted, at first, little attention amongst
continental philosophers. The introduction of the work into France
was due mostly to Voltaire. During his stay in England from 1726
to 1729, he became a whole-hearted convert. While he may not have
met Newton personally, he certainly became acquainted with Mrs.
Catherine Barton. On his return, he wrote a number of con¬
troversial tracts on the advantages of the Newtonian system over that
of Descartes, and drew the attention of his countrymen to that un¬
known mechanics.

The development of mechanics from the Principia into the most
nearly exact of the sciences, during the latter part of the eighteenth
century, was due to a succession of remarkable mathematicians in
France and Germany. The principal cause, why the continental
writers had a distinct advantage over their British contemporaries,
was the overpowering influence of Newton on his countrymen; they
unreservedly subjected themselves to his unquestioned authority.
As a result, they persisted in using his geometrical method and made
but ineffectual attempts to develop his fluxions into a useful tool.
Now, the flaws in Newton’s armour were an impatience of criticism,
and an irritability when pressed to explain his method of thought, or
to justify his assumptions. To him, a methodical exposition was un¬
necessary; he apparently grasped the solution of a problem as a
whole, but such a faculty does not make the teacher or assist in build¬
ing a new school of thought.

The continental philosophers were not subjected to such an in¬
fluence; international jealousies had been aroused by the controversy
which had arisen over the discovery of the calculus, and their sym¬
pathy was overwhelmingly on the side of Leibniz. The British, and
Newton himself, were criticised for what was thought to have been

ordered the whole company to disperse and return to their colleges. This strange visitation
was received with ridicule. Twice again he repeated the visit; nor did he stop at that,
but drew a formal complaint which he presented to the Vice-Chancellor and Heads. Un¬
fortunately for him, the ridiculous affair got into print, and his action became one of the
stock stories.

320

ISAAC NEWTON

an unjust attack on the character of a great and honoured man. It is
not surprising that they ignored Newtonian fluxions, which was
limited in its scope and deliberately obscure in its statement, and
cultivated the calculus of Leibniz which had been stated clearly,
and had been given an excellent nomenclature. The secretive tem¬
perament of Newton had snatched from him the fruit of his great
discovery. Thus fluxions languished while the calculus was rapidly
developed by the Bernoullis, and others, into the most powerful tool
of modern analysis, as fundamental and universal in mathematics
as the law of gravitation is in physics. The work of Euler, D’Alem¬
bert, and Lagrange, aided by others overshadowed only by such
giants, created a marvellous structure out of Newtonian mechanics,
with the aid of the calculus, and made it intelligible to the world.

The full significance of the Principia was not evident till Laplace
produced his Mecanique celeste in which he fused into a homogene¬
ous doctrine all the scattered work from Newton to Lagrange. In
this great synthesis, he attempted to examine the results of all previ¬
ous mechanicians, to correct them, and to show that the solar system
is a periodic and stable configuration governed solely by the uni¬
versal law of gravitation. Like Descartes, he portrayed the universe
as a vast machine obedient to inexorable mechanical laws; and his
famous Hypothesis is probably the utmost stretch of the human
mind in portraying the origin and operation of a world machine;
for whose guidance, as he haughtily informed Napoleon, there was
no need of a God.

Although the title of Newton’s treatise is the Mathematical Prin¬
ciples of Natural Philosophy, it was not intended to be an orderly
exposition of natural phenomena; but rather to prove that the law
of universal attraction of matter would account for all the motions
of the planetary bodies, and for the dynamic phenomena observed
on the earth. As a scientist, Newton is the successor of Galileo and,
with the exception of the new law of attraction, their work is so
intimately connected that it cannot be disentangled. They both
sought to found a science of mechanics on a system of forces, whose
sole function was to produce a measurable change of motion, in
place of the mediaeval science which had developed from Aristotle’s
metaphysics of natural positions and natural motions.

As an immediate consequence of Galileo’s discovery of the laws of
force, Descartes had, in his Systeme du Monde, elaborated a purely
mechanistic cosmogony. To account for gravitation, and for the

THE PRINCIPIA

3 21

orbital motions of the planets, he imagined all space to be a con¬
tinuum in which vast vortices drove the planets and their satellites
along their orbits by the friction of the whirling motion. The cos¬
mogony of Descartes was developed with a fascinating clarity of
diction and with specious simplicity of illustration; it seized on the
imagination of the world and was firmly established in the universi¬
ties. To displace this explanation of the orbits of the planets, New¬
ton had to oppose the idea that the natural motion of a planet was
along a straight line, and that its curvilinear path was the result, not
of forces along the path, but directed radially towards a fixed centre.
He had further to prove that the Cartesian vortices were impossible as
a dynamic system. And to break down this hypothesis, he chose to
depend solely on rigorous geometrical theorems rather than on an
appeal to the imagination; it is no wonder that even the most enlight¬
ened scientists failed to understand his purpose.

While it is true that the natural philosophers of the Renaissance,
beginning with Copernicus, attempted deliberately to replace the
scholastic science with a system of mechanical laws, based on ex¬
perimental observation, and expressed in mathematical formulae,
yet they frequently failed to make the break complete, and fell under
the influence of the old dogmatic authority. So we find Newton,
who proposed to limit himself strictly to the new so-called Pythag¬
orean school, or the Baconian inductive method as it was beginning
to be called, also prefaced his work with a set of purely metaphysical
definitions. But we should bear in mind that this introduction has
little, or no, connection with his main discussion of physical laws.

The universe, which Newton proposes, is a very restricted and
artificial one; it is a machine composed of bodies whose only at¬
tributes are position, extension, and mass, and of forces whose sole
function is to cause motion and its variation. All life and its direct
activities have no effect, and are banished from this universal ma¬
chine, which moves and acts in obedience to rigorous mechanical
law. Man is quite apart from the objective world and, as a rational
being, he is limited to observing and interpreting its phenomena.
His only contact with the outside world is through mechanical ac¬
tions impressed on his nerves and by them transmitted to a sensorium
in his brain. Man’s rational soul, assumed to be an entity apart from
his brain, then interprets these nerve stimuli as sight, sound, taste,
etc.; interpretations which are purely subjective, and incapable of
mechanical formulation. Thus, there exists, so far as physical science

322

ISAAC NEWTON

is concerned, an unbridgeable gap between the mechanical outer
world, and the inner realm of sensations and ideas.

The fundamental postulates for such a mechanistic universe are
the reality of substance (it is indifferent whether it be called matter,
or electricity, or quanta) existing as bodies, formally limited in an
empty and infinite space; and of force, or action, which produces
variations of position and motion. Newton next accepts the classi¬
fication, made by Galileo, of primary and secondary qualities. The
first class are those which are inherent in bodies and inseparable from
them, and without which they could not exist; the secondary quali¬
ties are those which, while distinguishing bodies, are not necessary
to them; that is, if the secondary qualities were abstracted from a
body it would still exist as a body. And, like Galileo and Descartes,
he assigned to the first class, extension, form, position, and such other
mechanical qualities as are needed to specify a body in time and
space; all other qualities are subordinate and secondary to them.

Newton s empirical and inductive philosophy has, naturally, not
escaped criticism. It presupposes a naive belief in the reality of the
objective world, whose attributes are not only independent of the
observer, but are also concordant with his observation. The first
serious attack was made by Berkeley. 32 He had studied Descartes
and Newton with care, and had come to the conclusion that such a
pure empiricism entirely neglected the factor of the perceiving mind.
When, for example, we say that we see an object, it is not the object,
but the sensation of sight perceived by the mind, which exists. If we
merely close the eyes, all the visible attributes of an object vanish.
And so it is with all the other sensations. The objective world, so far
as we are concerned, does not exist except as the mind observes and
interprets it. No one can, I think, disagree with him, that the ob¬
jective world cannot be postulated as something apart from the per¬
ceiving mind, and he certainly exposed an essential weakness of the
scientific method; by the empirical method, we may develop a logical
system of an objective world; but, because we must interpret it as it
appears to our minds, we can have no assurance that our interpre¬
tations and the facts of nature are the same, or even concordant.
When, however, Berkeley passes into pure idealism, and argues that
nothing exists except the perception in the mind, he then denies
what he cannot prove; and the possibility, even great probability,
remains that we can attain to an approximate knowledge of the real

32 A New Theory of Vision. London, 1709.

THE PRJNCIPIA

323

nature of phenomena by the comparison of the perceptions of sev¬
eral persons, or by the knowledge derived from a sense organ not im¬
mediately involved, as when we record temperature changes by see¬
ing a thermometer. The later, and acute, criticism of Hume did
much to show the impossibility of a pure inductive philosophy.

As the word, science, has gradually been arrogated to almost all
branches of knowledge, the assumption that the mechanical at¬
tributes of matter are to be given a peculiar necessity has been more
and more criticised. Of late, for example, Professor Whitehead has
attacked the distinction between primary and secondary qualities,
claiming that the attributes of extension, position, and other mechan¬
ical data, are no more fundamental, nor more inseparable from mat¬
ter, than are other attributes such as colour and temperature. He
evidently cannot deny that those qualities are fundamental so long
as we are studying mechanical problems. He is right in asserting that
the phenomena of light and heat are direct perceptions and cannot
be identified with, nor explained by, mechanical attributes; he is
also right in asserting that the phenomena of life are not mechanical
and that, therefore, the biological sciences cannot base their laws, and
their method, on physical dynamics. Up to this point, one would nat¬
urally assume that Professor Whitehead was advocating a philosophy
of dualism of two worlds, the vital and the material, and that each
has its own laws and its own method of study. But not at all. With
the reluctance of the mind to accept such an inevitable conclusion, he
at once proceeds to create a new monistic philosophy. Since life can¬
not be explained by mechanics, let us assume that physical energy
and action are manifestations of an universal life force, something
akin to Bergson’s elan vital, or self-creative evolution.

But it is not Newton, whom Professor Whitehead really criticises,
nor is it his mechanistic philosophy. Newton explicitly states that he
will discuss only those objective phenomena which are mechanical,
and which can be demonstrated geometrically; and, if such be his
purpose, no one can in justice condemn him for assuming mechan¬
ical attributes to be necessary and fundamental for his limited field.
It is rather the biologists, the psychologists, and the sociologists, who
have dragged the science of mechanics out of its proper limits; who
have attempted to make man into a machine, and all his sensations
mechanical.

Although Newton’s general or philosophic definitions have little
to do with his mechanics, they have been cited so constantly as the es-

3^4

ISAAC NEWTON

sence of his dynamics that they must be discussed. In his first defini¬
tion, he identifies a body by mass, and it has been stated by all writers
on mechanics, so far as I can remember, that a body is of itself inert;
or, to express it vulgarly, matter is essentially dead. But, in so inter¬
preting his idea, the remainder of this definition, and his third def¬
inition, have been disregarded. On the contrary, he makes force the
essential attribute of matter, and this force is known to us by our
sense perception of muscular effort, or weight. In support of this
interpretation, the third definition reads: “The vis insita, or innate
force of matter, is a power of resisting, by which every body, as much
as in it lies, endeavours to persevere in its present state. .. And in
explanation, he adds “this vis insita, may, by a most significant name,
be called vis inertiae, or force of inactivity Now this force is not
one which produces change, or requires the existence of another
body; it is that which endeavours to preserve the identity and stabil¬
ity of the body in space and time.

In addition to this innate force, Newton next postulates another
entity which he calls an impressed force, and “this force consists in
action only.” It is not an essential property of a body but acts on it
from the outside and produces change and variety. It also requires
the existence of two bodies to be brought into play, and it resides in
neither. Thus he gives to force the double and paradoxical roles of
inactivity and activity.

There can be little doubt but that his definition of impressed force,
as something detachable from matter, was based on his discovery of
universal attraction. He several times insisted that he postulated its
existence solely as a matter of experience, and when he speculated on
its cause he invariably assigned to it an aethereal or hypothetical
medium and, at times, suggested that this medium may be imma¬
terial,—the divine power of God. 33 To make his meaning more em¬
phatic, he distinguished, in the four following definitions, the vis
insita from the vis impressa by the distinction between centrifugal
force and centripetal force. To illustrate his idea, let us consider a
planet revolving about the sun. In each there is an innate force of
inertia {vis insita ); the planet of itself endeavours to move in a
straight line, which he defined later as a natural state, and the sun
endeavours to remain at rest. But in addition, there is a centripetal
force of attraction {vis impressa ), inherent in neither, which com-

33 In this identification of an infinite medium, or of space, with the active cause of universal
force, we must recognise the influence of Henry More, and we should suspect that he
depended much on Newton’s scientific work.

THE PRINCIPIA

325

pels both bodies to change their natural states. If this interpretation
of Newton’s fundamental postulates is correct, he avoided the dilem¬
ma of making bodies both inert and active, but he fell into the equal
difficulty of defining force as that which produces stability and varia¬
tion, and is both innate and impressed on matter. The fact is, that the
subject lies outside the field of science which can discuss only
phenomena, and not their ultimate causes. The same may be said of
Newton’s long discussion of absolute, and relative, time and space.
Such questions may be proper for metaphysicians to discuss, though
to the present time, the results of their discussion seem somewhat un¬
certain, to say the least. For the physicist, fortunately, the absolute is
not significant, and his problems concern only relative, and meas¬
urable, space, and time.

After his general definitions, Newton announced three axioms, or
laws of motion. The first law, that every body perseveres in its state
of rest, or of uniform motion unless acted upon by an impressed
force, is merely a repetition of his former definition of the vis insita.
If we remember that a state of absolute rest is unrecognisable, and
that his assumption of a mutual attraction between every pair of
existing bodies precludes any body from being free from impressed
forces, it is evident that the law is purely hypothetical, and not veri¬
fiable by scientific experimentation.

The third law, that action and reaction are equal and opposite,
must also be regarded as purely hypothetical. This can be best
shown by considering Newton’s illustrations. He says that if a horse
draws a stone tied to a rope, the horse will be pulled back as much as
the stone is pulled forward. But a dead horse cannot initiate a pull
and the previous will to move of a live horse must be excluded from a
mechanistic law. Again his illustration of impact is defective. If two
bodies collide, the equality of action and reaction involves the mass,
or the hypothetical vis insita, as well as the resultant velocities. Even
if we admit the explanation of impact by Hooke’s law of elasticity
to be satisfactory, there are cases which are not explicable even by
that empirical fact. If light or heat from the sun, or any other source,
falls on a reflecting body it produces an observable pressure and dis¬
placement away from the source. In this case, where the one body is
acted upon there is no direct mechanical reaction on the other. For
example, the light of the sun repels the tail of a comet, but there is no
repulsion of the sun. Thus, to explain the laws of impact a molecular
force of repulsion must be assumed; and radiant pressure requires

ISAAC NEWTON

326

the assumption of light corpuscles, or of an aether possessing the at¬
tribute of ponderable mass.

There thus remains only the second law and, as it defines the func¬
tion of a force and expresses its measurement without involving
hypothetical ideas of the nature of bodies and force, it is scientific and
fundamental. It states that the measurable ratio of force to change
of motion is a constant, and that this constant may be taken as the
measure of the mass of a body. Such a definition of mass evidently
does not involve the hypothetical concept of a vis insita, or the
esoteric idea of effort, or the vitalistic endeavour to persevere, in
material bodies; but leaves it as a mere numerical coefficient.

The laws of motion, and their corollaries, are followed by a
scholium in which Newton assigned the honour of discovery of the
first two laws to Galileo who by direct experimentation established
the correct formula for a force. The third law follows, according to
Newton, from the work of Wallis, Wren, and Huygens, on impact.
To conclude our review of the preface, his metaphysical ideas have
been successfully attacked, the cause of gravitation has been the sub¬
ject of endless discussion and of no conclusion, and the attempts to
include the phenomena of heat, light, electricity, and life in a
mechanical system have invariably failed; but we should not over¬
look the fact that all these are foreign to the mechanics of ponderable
bodies which is, in truth, the sole subject of the Principia.

The first book opens with the geometrical proof of a few general
theorems in mechanics, and from there Newton immediately passes
to the discussion of orbital motion. He first proves that, if a body
moves in a conic section about a stationary body situated at its focus,
a force of attraction which is inversely proportional to the square of
the distance between them will be a sufficient cause of the motion.
And he develops his theory of celestial mechanics on the basis that
this centripetal force, or gravitation, is the only force necessary to
account for the elliptic orbits of the planets and of their satellites;
also, all perturbations in their motions are caused by the same force.
If we further assume that a foreign body, such as a comet, enters the
system with a rectilinear motion its path will be an ellipse, an
hyperbola or a parabola according to the initial value given to its
speed. Generalising this idea, from the principle that the action of
the whole is the sum of the action of its parts, Newton assumes
gravity to be the universal cause of motion. In making such a gen¬
eralisation he had to rely solely on celestial motions since it was then

THE PRINCIPIA 327

experimentally impossible to prove the attraction of small bodies on
each other. This has since been acomplished.

After the discussion of the problem of the attraction of two
bodies, Newton derives an approximate solution of the problem of
three bodies where one of them is so large as to be considered sta¬
tionary. In this section the motion of the moon under the action of
the sun and the earth is considered; also the problems of Saturn’s
rings, the tides, the shape of the earth, the precession of the equinoxes
are dealt with mathematically for the first time. The book closes
with the attempt to explain the laws of the reflection, refraction, and
diffraction of light by a similar force of attraction between light
corpuscles and matter.

Practically the entire second book is devoted to a discussion of the
motion of fluids, and the effect of friction on the motion of solid
bodies in fluids. At first sight, surprise may be felt that so large a
part should have been devoted to this subject. But Newton’s pur¬
pose is explained if we recall that, although he had proved gravity
would account fully for planetary motion, he had the very difficult
task of demonstrating not only that the hypothesis of Cartesian
vortices was unnecessary, but also that they were incapable of satis¬
fying Kepler’s laws. This hypothesis reigned supreme, and it will be
remembered that Newton, himself, when his first calculation in¬
dicated the insufficiency of gravity as a cause, is said to have believed
a vortex to be necessary. It is evident that if space be filled with vast
vortices which carry the planets in their orbits, then space must be
considered to be a frictional fluid.

Newton first attacks the problem by proving that circular motion
in a frictional medium would, under the action of gravity, degen¬
erate into a spiral path ultimately causing the planet to fall on the
central body. He therefore concludes, since there is no evidence of
instability in planetary orbits, that space is empty and devoid of
friction. Finally, in proposition 52, he attacks the problem directly
and proves that a vortex will not account for Kepler’s laws. This
proposition states: “If a solid sphere, in an uniform and infinite
fluid, revolves about an axis given in position with an uniform mo¬
tion, and the fluid be forced round by only this impulse of the
sphere; and every part of the fluid perseveres uniformly in its mo¬
tion: I say, that the periodic times of the parts of the fluid are as the
squares of their distances from the centre of the sphere.” The proof
of this proposition, with the corollaries derived from it, was really

ISAAC NEWTON

328

the death-blow of the Cartesian hypothesis; for, in a scholium he re¬
marks: “I have endeavoured in this proposition to investigate the
properties of vortices, that I might find whether the celestial phe¬
nomena can be explained by them; for the phenomenon is this, that
the periodic times of the planets revolving about Jupiter are in the
sesquiplicate ratio of their distances from Jupiter’s centre ; 34 and the
same rule obtains also among the planets that revolve about the sun.”

In addition to the principal thesis of the second book, Newton
shows his marvellous power as a geometrician. There is a wealth of
material on the motions of pendulums, efflux of fluids, and wave
motion. Besides the mathematical demonstration of the laws of
fluids, he supported his argument with elaborate series of experi¬
ments. In accuracy of measurement and ingenuity of invention, I
think, Faraday alone was equal to him; and when we remember
that, to this experimental power, there was also an unrivalled
mathematical genius, which Faraday totally lacked, the combination
justifies the awe with which his contemporaries regarded him, and
still makes us regard him as the supreme natural philosopher.

Newton concludes the second book with the statement that he had
accomplished the task he had set out to do: “The hypothesis of
vortices is utterly irreconcilable with astronomical phenomena, and
rather serves to perplex than explain the heavenly motions. How
these motions are performed in free space without vortices, may be
understood by the first book; and I shall now more fully treat of it
in the following book.” And in the prefatory opening of the third
book he explains what his purpose had been. He had not tried a
descriptive narrative of phenomena, but to outline a science of
mechanics, founded on a few laws of motion and force known to be
true from experience, and developed by mathematics. While he il¬
lustrated his conclusions by a few phenomena, he felt he could leave
the applications of the theory, which he had advanced, to the work
of succeeding natural philosophers. He evidently thought it would
have distracted his readers from following his main argument if he
had included descriptive matter. He had, of course, meditated on the
vast number of cosmic phenomena which his proof of the universal
attraction of matter explained. It will be remembered that he had
prepared a third book in which he had set forth the applications of

84 This is the statement of Kepler’s law that the cubes of the distances of planets are
proportional to the squares of their periods; thus the law of vortices which requires the
squares of their distances to be proportional to their periods is erroneous.

THE PRINCIPIA

329

his theory of gravity and then, at the last moment, would have sup¬
pressed it except for the earnest entreaty of Halley.

The introduction to this third book is curiously indicative of New¬
ton’s character, a strange mixture of modesty and pride. “It remains
that,” he wrote, “from the same principles, I now demonstrate the
frame of the System of the World. Upon this subject I had, indeed,
composed the third book in a popular method, that it might be read
by many; but afterwards, considering that such as had not suffi¬
ciently entered into the principles could not easily discern the
strength of the consequences, nor lay aside the prejudices to which
they had been many years accustomed, therefore, to prevent the
disputes which might be raised upon such accounts, I chose to reduce
the substance of this book into the form of propositions (in the
mathematical way), which should be read by those only who had
first made themselves masters of the principles established in the pre¬
ceding books: not that I would advise any one to the previous study
of every proposition of those books; for they abound with such as
might cost too much time, even to readers of good mathematical
learning.”

On the rare occasions when Newton discusses his own work, he
does it with the calm assurance of its high value. A man of his pene¬
trating mind could not have failed to know that he had accomplished
a colossal piece of work and that he had placed science on a new and
firm foundation. He knew that only a very few could understand it,
and even they would probably fail to see the unlimited consequences
which he had laid before them. For years, he had lived in a sort of
ecstasy of meditation as the laws of the cosmos developed in his
mind, and now that he had reluctantly published his thoughts, he
would ward off the criticisms of those who would not exercise the
same labour to understand him. And with this haughty pride there
was an equal modesty when he contemplated what little he could do
to solve the inexplicable mysteries of the physical universe, and
there was true humility in his submission to the belief that “this most
beautiful system of the sun, planets, and comets, could only proceed
from the counsel and dominion of an intelligent and powerful
Being .” 35

Newton’s true modesty is shown most clearly in his recognition
that mere activity of a vigorous mind, not only cannot arrive at use¬
ful scientific conclusions by any mathematical or verbal logic unless

35 Gen. Schol. Book III, Principia.

330

ISAAC NEWTON

it is based on established facts of experience; but also that such un¬
supported activity is pernicious in that it dazzles the minds of others
and hinders true knowledge. And as proof, he cited the grandiose
cosmogony of Descartes which, being founded on an inward senti¬
ment of knowledge, “rather serves to perplex than to explain the
heavenly motions.” Not only did Newton believe that the first com¬
mandment of science was that theory must be based on experi¬
mental facts, but he also was ready to abandon his own without
hesitation if it failed in that support. Thus, Conduitt made a note
in his intended life of Newton that Molyneux, a mathematician, told
him: “After he and Mr. Graham and Bradley had put up a per¬
pendicular telescope at Kew to find out the parallax of the fixed
stars, they found a certain nutation in the earth which they could
not account for, and thought destroyed the Newtonian system—M.
told I. N. as gently and tactfully as he could— But all I. N. said in
answer was, ‘It may be so, there is no arguing against facts and ex¬
periments.’ ” 36

The most important applications of the theory of attraction to the
explanation of phenomena, discussed in the third book, are various
laws of planetary motion, the lunar theory, the precession of the
equinoxes, the tides, and the planetary theory of comets. Of these
his proof of the orbital paths of comets was probably the most nota¬
ble prediction of Newton’s theory. The treatment of the lunar the¬
ory, as given in the first edition of the Principia, is, as he himself ex¬
pressly stated, only a specimen or fragment which outlined some of
the more evident lunar inequalities due to the perturbing action of
the sun. In the second edition this subject was corrected and ex¬
panded, but he frequently expressed his disappointment that he did
not carry on the work to a more perfect conclusion. That he did
occupy himself intermittently with the problem is known by the
mass of papers on the subject which is preserved in the Portsmouth
Collection. He often laid the blame on Flamsteed for a lack of co¬
operation in providing him with the data of observations; but it is
more likely that his lack of interest in science after the publication
of the Principia and his official life when he went to London, are the
real reasons why the lunar theory was never completed.

The Principia, when it first appeared, ended as casually as if the
author had grown weary of the task, and had suddenly decided to

36 Portsmouth Collection.

THE PRINCIPIA

33i

write no more. But a General Scholium was added to the second
edition in which Newton sums up the purpose and accomplishment
of the work. He has, he declared, shown the Cartesian hypothesis to
be untenable; and, although he has demonstrated that a universal
force of gravity will account mathematically for the major phe¬
nomena of the solar system, yet he is just as convinced that no mere
mechanical causes could give birth to so many regular motions, and
that this most beautiful system presupposes, by the very fact of its
regularity, the existence of a divine Creator. He then affirms his be¬
lief in an omniscient and omnipotent God, whose attributes we may
learn to know through his laws and works. Finally, since he will
frame no hypotheses, he has assigned no cause of the power of
gravity, “It is enough that gravity does really exist, and act according
to the laws which we have explained, and abundantly serves to ac¬
count for all the motions of the celestial bodies, and of our sea.”
Lest, however, anyone should think he held that gravity was an
occult and essential attribute of matter, he intimates that there
may be an elastic and electric Spirit which pervades and lies hid in
all gross bodies. “But these are things that cannot be explained in
few words, nor are we furnished with that sufficiency of experiments
which is required to an accurate determination and demonstration
of the laws by which this electric and elastic Spirit operates.” As it
will be shown later, this scholium was added to the text during the
preparation of the second edition, not because Newton felt that it
should be an integral part of his argument, but because he had been
urged to defend himself against personal attacks made on his philos¬
ophy, and on his religion.

It was instructive, in view of the pretensions of modern pseudo¬
science, to emphasize Newton’s modest statement of what he had
accomplished in the Principia . And, as a like example of the same
spirit, the conclusion of Aristotle’s Organon is equally significant:

“Moreover, on the subject of Rhetoric there exists much that has
been said long ago, whereas on the subject of Reasoning we had noth¬
ing else of an earlier date to speak of at all, but were kept at work
for a long time in experimental researches. If, then, it seems to you
after inspection that, such being the situation as it existed at the start,
our investigation is in a satisfactory condition compared with the
other enquiries that have been developed by tradition, there must
remain for all of you, or for our students, the task of extending us

ISAAC NEWTON

332

your pardon for the shortcomings of the enquiry, and for the dis¬
coveries thereof your warm thanks .” 37

It is a notable fact that these two works, probably the two most
stupendous creations of the scientific brain, are now under attack,—
the Organon by modern symbolists in logic, and the Principia by the
relativists in physics. But Aristotle and Newton will be honoured
and used when the modernists are long forgotten.

The effect of the Principia was revolutionary so soon as its power
and scope were appreciated; due to the labours of a succession of
mathematical physicists, a remarkable science of mechanics was
developed. By abstracting all the qualities of bodies except their
vires insitae concentrated at their centres of inertia, the positions and
motions of these centres, and the existence of the Newtonian force
of attraction along a line joining each pair of these points, the nearest
approach to an ideal science was created. Given, the masses, posi¬
tions, and motions of a system of bodies at any instant; then, with
extraordinary precision, their future positions and motions could be
calculated by a set of rigorous mathematical equations. In the mean¬
while, and especially during the nineteenth century, the sciences of
heat, light, and electricity made rapid strides. It was natural, and
even inevitable, that theorists should turn to mechanics for a method
to explain the phenomena of those sciences. As a result of these ef¬
forts, there was evolved an elaborately complex, and highly artificial,
objective world of merely masses and motions which had but a faint
resemblance to our sense perceptions.

Unconsciously, the physical world was divided into two almost
unrelated realms, a perceptible cosmos of finite bodies, and a
microcosm of the infinitesimally small. On the one hand, the actions
of a drop of water, for example, were studied as if the body were a
simple mechanical mass. On the other hand, the same drop was
imaginatively conceived to be an enormously complex aggregation
of an indefinite number of atoms, each indefinitely small, and all
compacted within the superficies of the drop to form a planetary
system. Having first successfully created a mechanics of the system
as a unit, by abstracting from it all so-called secondary qualities,
such as chemical action, heat, light, electricity, etc., each quality was
then successively restored to the system and explained by endowing
the atom with the attribute as a consequence of his own motion.

87 Cf. Translation of Aristotle's Wor\s. Vol. I, Ed. by Ross. Oxford.

THE PRINCIPIA

333

Thus, there was elaborated a mechanical hypothesis of the atom,
agreeing as nearly as possible with the principles and laws of New¬
tonian dynamics of ponderable bodies.

By the twentieth century, the mechanical hypothesis of the atom,
or molecular physics as it was called, had become an unwieldy
burden, and no imaginable atom could even satisfy the phenomena
of one field of physics; while it quite failed as the deus ex machina
of all of them. Newtonian mechanics, which was so effective an in¬
strument in its own domain, not only began to show signs of wear,
but actually cracked at every joint, when it was thus stretched to
cover subjects to which it was never intended to apply. In this pre¬
dicament, theorists, with the hope of preserving a unity of method,
gradually made an abstraction of the concrete atom. The boldest at¬
tempt towards a philosophy of pure idealism is Professor Einstein’s
Generalised Theory of Relativity. By an explicit paradox, and by the
use of a geometry not limited by our sense perception of only three
dimensions, he has proposed a new synthesis. The world, as he pic¬
tures it, is purely idealistic, a formula expressed by mathematical
equations incapable of explicit solution. The brute facts of experi¬
ence are an illusion without objective existence. In one respect, we
must admit that truth is formular, either verbal or mathematical.
But the philosophy, which is merely a logical exercise of the active
mind, and ignores the world of brute facts, may be interesting, but it
ultimately evaporates into a scholasticism. And if it persists, it will
cause the decadence of science as surely as the mediaeval scholas¬
ticism preceded the decadence of religion.

As I have said before, it is popularly believed that modern
criticism has at last broken down the classical mechanics. But New¬
tonian dynamics, in its own restricted field, can be superseded only
by demonstrating experimentally that two bodies of sensible size,
when separated by a finite distance, do not exert a mutual force of
attraction: it can be corrected only by demonstrating experimentally
that this force of attraction does not vary exactly as the inverse
square of the distance. Till now, at least, both direct and indirect
observation confirms this law. For great distances astronomy con¬
firms it accurately; for terrestrial distances, our laboratory experi¬
ments are difficult and their accuracy is not great; for molecular dis¬
tances, if the force exists, it is almost certainly proportional to a
higher power than the square. The influence of other actions has
been investigated. That gravity is affected by temperature, by elec-

334

ISAAC NEWTON

trical or magnetic charges, or by the material of the bodies, is ex¬
tremely doubtful; the evidence is preponderantly against any ap¬
preciable influence. If the force is a function of the velocity, it is
unaffected by any velocity known to be attainable by a ponderable
body.

From its publication till today, the Principia has been the source of
all theoretical physics and, so far as one can predict, it will continue
indefinitely to be a model of the scientific method. We should re¬
gard it with the reverence expressed in Halley’s verse:

“Nec fas est propius Mortali attingere Divos.”

CHAPTER X

THE ALBAN AFFAIR AND THE REVOLUTION. CORRE¬
SPONDENCE WITH JOHN LOCKE. THE BOYLE
LECTURES. SERIOUS ILLNESS

1687-1693

W hile Newton was so deeply absorbed in the composition
of the Principia that he was hardly aware of the ordinary
functions and regimen of life, England was facing one of
the gravest crises in her history. He, in the quiet and retirement of
his study, was seeking to elucidate the laws of a universe so rigorous
and exact that, once instituted by God, they were subject to no change
and to no interruption in the uniform flow of their effects. In all the
rest of England, other men were agitated by the accession of James II
to the throne; even the most thoughtless viewed the future with ap¬
prehension and alarm, lest the comparative peace of the previous
reign should be wrecked in a return to the turbulence and lawless¬
ness of civil strife. It is not the least curious consequence of the
events which followed, that Newton should have been drawn out of
his scholarly creative life and turned into a public official and
courtier.

The first solemn promises of tolerance were scarcely made by the
new King before the nation realised that religious strife would again
shake the foundations of the government. James not only openly
professed the Roman Catholic religion, but declared it to be his
dearest wish to bring the country back to that faith. It is very
probable that he might have removed many of the restrictions which
had been imposed on the Catholics since the time of Elizabeth, and
might have obtained civil and religious freedom for them, if he had
exercised tact and self-restraint, so fearful were the people that in¬
tolerance would bring a return to civil war. But, against the warn¬
ing and advice of Rome to proceed cautiously, he listened to the
counsel of the Jesuit coterie, who were weary of the temporising
policy of his brother, and who were totally unable to judge the

335

ISAAC NEWTON

336

English character. Urged by them, he adopted the policy of absolute
rule, of intimidation, and of debauching the law courts to give his
acts the specious plea of legality.