Born: 4 Jan 1643
in Woolsthorpe, Lincolnshire, England
Died: 31 March 1727
in London, England
Isaac Newton's life can be divided into three quite distinct
periods. The first is his boyhood days from 1643 up to his appointment to a
chair in 1669. The second period from 1669 to 1687 was the highly productive
period in which he was Lucasian professor at Cambridge. The third period
(nearly as long as the other two combined) saw Newton as a highly paid
government official in London with little further interest in mathematical
Isaac Newton was born in the manor house of Woolsthorpe, near
Grantham in Lincolnshire. Although by the calendar in use at the time of his
birth he was born on Christmas Day 1642, we give the date of 4 January 1643 in this biography
which is the "corrected" Gregorian calendar date bringing it into
line with our present calendar. (The Gregorian calendar was not adopted in
England until 1752.) Isaac Newton came from a family of farmers but never knew
his father, also named Isaac Newton, who died in October 1642, three months
before his son was born. Although Isaac's father owned property and animals
which made him quite a wealthy man, he was completely uneducated and could not
sign his own name.
You can see a picture of Woolsthorpe Manor as it is now.
Isaac's mother Hannah Ayscough remarried Barnabas Smith the
minister of the church at North Witham, a nearby village, when Isaac was two
years old. The young child was then left in the care of his grandmother Margery
Ayscough at Woolsthorpe. Basically treated as an orphan, Isaac did not have a
happy childhood. His grandfather James Ayscough was never mentioned by Isaac in
later life and the fact that James left nothing to Isaac in his will, made when
the boy was ten years old, suggests that there was no love lost between the
two. There is no doubt that Isaac felt very bitter towards his mother and his
step-father Barnabas Smith. When examining his sins at age nineteen, Isaac
Threatening my father and mother Smith to burn them and the
house over them.
Upon the death of his stepfather in 1653, Newton lived in an
extended family consisting of his mother, his grandmother, one half-brother,
and two half-sisters. From shortly after this time Isaac began attending the
Free Grammar School in Grantham. Although this was only five miles from his
home, Isaac lodged with the Clark family at Grantham. However he seems to have
shown little promise in academic work. His school reports described him as
'idle' and 'inattentive'. His mother, by now a lady of reasonable wealth and
property, thought that her eldest son was the right person to manage her
affairs and her estate. Isaac was taken away from school but soon showed that
he had no talent, or interest, in managing an estate.
An uncle, William Ayscough, decided that Isaac should prepare
for entering university and, having persuaded his mother that this was the
right thing to do, Isaac was allowed to return to the Free Grammar School in
Grantham in 1660 to complete his school education. This time he lodged with
Stokes, who was the headmaster of the school, and it would appear that, despite
suggestions that he had previously shown no academic promise, Isaac must have
convinced some of those around him that he had academic promise. Some evidence
points to Stokes also persuading Isaac's mother to let him enter university, so
it is likely that Isaac had shown more promise in his first spell at the school
than the school reports suggest. Another piece of evidence comes from Isaac's list
of sins referred to above. He lists one of his sins as:-
... setting my heart on money, learning, and pleasure more than
which tells us that Isaac must have had a passion for learning.
We know nothing about what Isaac learnt in preparation for
university, but Stokes was an able man and almost certainly gave Isaac private
coaching and a good grounding. There is no evidence that he learnt any
mathematics, but we cannot rule out Stokes introducing him to Euclid's
Elements which he was well capable of teaching (although there is evidence
mentioned below that Newton did not read Euclid before 1663). Anecdotes
abound about a mechanical ability which Isaac displayed at the school and
stories are told of his skill in making models of machines, in particular of
clocks and windmills. However, when biographers seek information about famous
people there is always a tendency for people to report what they think is
expected of them, and these anecdotes may simply be made up later by those who
felt that the most famous scientist in the world ought to have had these skills
Newton entered his uncle's old College, Trinity College
Cambridge, on 5 June 1661. He was older than most of his fellow students but,
despite the fact that his mother was financially well off, he entered as a
sizar. A sizar at Cambridge was a student who received an allowance toward
college expenses in exchange for acting as a servant to other students. There
is certainly some ambiguity in his position as a sizar, for he seems to have
associated with "better class" students rather than other sizars.
Westfall has suggested that Newton may have had Humphrey Babington, a distant
relative who was a Fellow of Trinity, as his patron. This reasonable
explanation would fit well with what is known and mean that his mother did not
subject him unnecessarily to hardship as some of his biographers claim.
Newton's aim at Cambridge was a law degree. Instruction at
Cambridge was dominated by the philosophy of Aristotle but some freedom
of study was allowed in the third year of the course. Newton studied the
philosophy of Descartes, Gassendi, Hobbes, and in
particular Boyle. The mechanics of the Copernican astronomy of
Galileo attracted him and he also studied Kepler's Optics. He recorded his
thoughts in a book which he entitled Quaestiones Quaedam Philosophicae (Certain
Philosophical Questions). It is a fascinating account of how Newton's ideas
were already forming around 1664. He headed the text with a Latin statement
meaning " Plato is my friend, Aristotle is my friend, but my best friend
is truth" showing himself a free thinker from an early stage.
How Newton was introduced to the most advanced mathematical
texts of his day is slightly less clear. According to de Moivre, Newton's
interest in mathematics began in the autumn of 1663 when he bought an astrology
book at a fair in Cambridge and found that he could not understand the
mathematics in it. Attempting to read a trigonometry book, he found that he
lacked knowledge of geometry and so decided to read Barrow's edition
of Euclid's Elements. The first few results were so easy that he almost
gave up but he:-
... changed his mind when he read that parallelograms upon the
same base and between the same parallels are equal.
Returning to the beginning, Newton read the whole book with a
new respect. He then turned to Oughtred's Clavis Mathematica and
Géométrie. The new algebra and analytical geometry of
Viète was read by Newton from Frans van Schooten's edition of
Viète's collected works published in 1646. Other major works of mathematics
which he studied around this time was the newly published major work by
van Schooten Geometria a Renato Des Cartes which appeared in two volumes
in 1659-1661. The book contained important appendices by three of van
Schooten disciples, Jan de Witt, Johan Hudde, and Hendrick
van Heuraet. Newton also studied Wallis's Algebra and it appears
that his first original mathematical work came from his study of this text. He
read Wallis's method for finding a square of equal area to a
parabola and a hyperbola which used indivisibles. Newton made notes
on Wallis's treatment of series but also devised his own proofs of the
Thus Wallis doth it, but it may be done thus ...
It would be easy to think that Newton's talent began to emerge
on the arrival of Barrow to the Lucasian chair at Cambridge in 1663 when
he became a Fellow at Trinity College. Certainly the date matches the
beginnings of Newton's deep mathematical studies. However, it would appear that
the 1663 date is merely a coincidence and that it was only some years later
that Barrow recognised the mathematical genius among his students.
Despite some evidence that his progress had not been
particularly good, Newton was elected a scholar on 28 April 1664 and received
his bachelor's degree in April 1665. It would appear that his scientific genius
had still not emerged, but it did so suddenly when the plague closed the
University in the summer of 1665 and he had to return to Lincolnshire. There,
in a period of less than two years, while Newton was still under 25 years old,
he began revolutionary advances in mathematics, optics, physics, and astronomy.
While Newton remained at home he laid the foundations for
differential and integral calculus, several years before its independent
discovery by Leibniz. The 'method of fluxions', as he termed it, was
based on his crucial insight that the integration of a function is merely the
inverse procedure to differentiating it. Taking differentiation as the basic
operation, Newton produced simple analytical methods that unified many separate
techniques previously developed to solve apparently unrelated problems such as
finding areas, tangents, the lengths of curves and the maxima and minima
of functions. Newton's De Methodis Serierum et Fluxionum was written in 1671
but Newton failed to get it published and it did not appear in print until John
Colson produced an English translation in 1736.
When the University of Cambridge reopened after the plague in
1667, Newton put himself forward as a candidate for a fellowship. In October he
was elected to a minor fellowship at Trinity College but, after being awarded
his Master's Degree, he was elected to a major fellowship in July 1668 which allowed
him to dine at the Fellows' Table. In July 1669 Barrow tried to ensure
that Newton's mathematical achievements became known to the world. He sent
Newton's text De Analysi to Collins in London writing:-
[Newton] brought me the other day some papers, wherein he set
down methods of calculating the dimensions of magnitudes like that of Mr
Mercator concerning the hyperbola, but very general; as also of resolving
equations; which I suppose will please you; and I shall send you them by the
Collins corresponded with all the leading mathematicians
of the day so Barrow's action should have led to quick recognition.
Collins showed Brouncker, the President of the Royal Society, Newton's
results (with the author's permission) but after this Newton requested that his
manuscript be returned. Collins could not give a detailed account but
de Sluze and Gregory learnt something of Newton's work
through Collins. Barrow resigned the Lucasian chair in 1669 to
devote himself to divinity, recommending that Newton (still only 27 years old)
be appointed in his place. Shortly after this Newton visited London and twice
met with Collins but, as he wrote to Gregory:-
... having no more acquaintance with him I did not think it
becoming to urge him to communicate anything.
Newton's first work as Lucasian Professor was on optics and this
was the topic of his first lecture course begun in January 1670. He had reached
the conclusion during the two plague years that white light is not a simple
entity. Every scientist since Aristotle had believed that white light was
a basic single entity, but the chromatic aberration in a telescope lens
convinced Newton otherwise. When he passed a thin beam of sunlight through a
glass prism Newton noted the spectrum of colours that was formed.
He argued that white light is really a mixture of many different
types of rays which are refracted at slightly different angles, and that each
different type of ray produces a different spectral colour. Newton was led by
this reasoning to the erroneous conclusion that telescopes using refracting
lenses would always suffer chromatic aberration. He therefore proposed and
constructed a reflecting telescope.
In 1672 Newton was elected a fellow of the Royal Society after
donating a reflecting telescope. Also in 1672 Newton published his first
scientific paper on light and colour in the Philosophical Transactions of the
Royal Society. The paper was generally well received but Hooke and
Huygens objected to Newton's attempt to prove, by experiment alone, that light
consists of the motion of small particles rather than waves. The reception that
his publication received did nothing to improve Newton's attitude to making his
results known to the world. He was always pulled in two directions, there was
something in his nature which wanted fame and recognition yet another side of
him feared criticism and the easiest way to avoid being criticised was to
publish nothing. Certainly one could say that his reaction to criticism was
irrational, and certainly his aim to humiliate Hooke in public because of
his opinions was abnormal. However, perhaps because of Newton's already high
reputation, his corpuscular theory reigned until the wave theory was revived in
the 19th century.
Newton's relations with Hooke deteriorated further when,
in 1675, Hooke claimed that Newton had stolen some of his optical
results. Although the two men made their peace with an exchange of polite
letters, Newton turned in on himself and away from the Royal Society which he
associated with Hooke as one of its leaders. He delayed the publication
of a full account of his optical researches until after the death of
Hooke in 1703. Newton's Opticks appeared in 1704. It dealt with the theory of
light and colour and with investigations of the colours of thin sheets
'Newton's rings' and diffraction of light.
To explain some of his observations he had to use a wave theory
of light in conjunction with his corpuscular theory.
Another argument, this time with the English Jesuits in Liège
over his theory of colour, led to a violent exchange of letters, then in 1678
Newton appears to have suffered a nervous breakdown. His mother died in the
following year and he withdrew further into his shell, mixing as little as
possible with people for a number of years.
Newton's greatest achievement was his work in physics and
celestial mechanics, which culminated in the theory of universal gravitation.
By 1666 Newton had early versions of his three laws of motion. He had also
discovered the law giving the centrifugal force on a body moving uniformly in a
circular path. However he did not have a correct understanding of the mechanics
of circular motion.
Newton's novel idea of 1666 was to imagine that the Earth's
gravity influenced the Moon, counter- balancing its centrifugal force. From his
law of centrifugal force and Kepler's third law of planetary motion,
Newton deduced the inverse-square law.
In 1679 Newton corresponded with Hooke who had written to
... that the Attraction always is in a duplicate proportion to
the Distance from the Center Reciprocall ...
M Nauenberg writes an account of the next events:-
After his 1679 correspondence with Hooke, Newton, by his
own account, found a proof that Kepler's areal law was a consequence of
centripetal forces, and he also showed that if the orbital curve is an
ellipse under the action of central forces then the radial dependence of the
force is inverse square with the distance from the centre.
This discovery showed the physical significance of Kepler's
In 1684 Halley, tired of Hooke's boasting [M
... asked Newton what orbit a body followed under an inverse
square force, and Newton replied immediately that it would be an ellipse.
However in De Motu.. he only gave a proof of the converse theorem that if the
orbit is an ellipse the force is inverse square. The proof that inverse square
forces imply conic section orbits is sketched in Cor. 1 to Prop. 13 in Book 1 of the second
and third editions of the Principia, but not in the first edition.
Halley persuaded Newton to write a full treatment of his
new physics and its application to astronomy. Over a year later (1687) Newton
published the Philosophiae naturalis principia mathematica or Principia as it
is always known.
The Principia is recognised as the greatest scientific book ever
written. Newton analysed the motion of bodies in resisting and non-resisting
media under the action of centripetal forces. The results were applied to
orbiting bodies, projectiles, pendulums, and free-fall near the Earth. He
further demonstrated that the planets were attracted toward the Sun by a force
varying as the inverse square of the distance and generalised that all heavenly
bodies mutually attract one another.
Further generalisation led Newton to the law of universal
... all matter attracts all other matter with a force
proportional to the product of their masses and inversely proportional to the
square of the distance between them.
Newton explained a wide range of previously unrelated phenomena:
the eccentric orbits of comets, the tides and their variations, the precession
of the Earth's axis, and motion of the Moon as perturbed by the gravity of the
Sun. This work made Newton an international leader in scientific research. The
Continental scientists certainly did not accept the idea of action at a
distance and continued to believe in Descartes' vortex theory where
forces work through contact. However this did not stop the universal admiration
for Newton's technical expertise.
James II became king of Great Britain on 6 February 1685. He had
become a convert to the Roman Catholic church in 1669 but when he came to the
throne he had strong support from Anglicans as well as Catholics. However
rebellions arose, which James put down but he began to distrust Protestants and
began to appoint Roman Catholic officers to the army. He then went further,
appointing only Catholics as judges and officers of state. Whenever a position
at Oxford or Cambridge became vacant, the king appointed a Roman Catholic to
fill it. Newton was a staunch Protestant and strongly opposed to what he saw as
an attack on the University of Cambridge.
When the King tried to insist that a Benedictine monk be given a
degree without taking any examinations or swearing the required oaths, Newton
wrote to the Vice-Chancellor:-
Be courageous and steady to the Laws and you cannot fail.
The Vice-Chancellor took Newton's advice and was dismissed from
his post. However Newton continued to argue the case strongly preparing
documents to be used by the University in its defence. However William of
Orange had been invited by many leaders to bring an army to England to defeat
James. William landed in November 1688 and James, finding that Protestants had
left his army, fled to France. The University of Cambridge elected Newton, now
famous for his strong defence of the university, as one of their two members to
the Convention Parliament on 15 January 1689. This Parliament declared that
James had abdicated and in February 1689 offered the crown to William and Mary.
Newton was at the height of his standing - seen as a leader of the university
and one of the most eminent mathematicians in the world. However, his election
to Parliament may have been the event which let him see that there was a life
in London which might appeal to him more than the academic world in Cambridge.
After suffering a second nervous breakdown in 1693, Newton
retired from research. The reasons for this breakdown have been discussed by
his biographers and many theories have been proposed: chemical poisoning as a
result of his alchemy experiments; frustration with his researches; the ending
of a personal friendship with Fatio de Duillier, a Swiss-born mathematician
resident in London; and problems resulting from his religious beliefs. Newton
himself blamed lack of sleep but this was almost certainly a symptom of the
illness rather than the cause of it. There seems little reason to suppose that
the illness was anything other than depression, a mental illness he must have
suffered from throughout most of his life, perhaps made worse by some of the
events we have just listed.
Newton decided to leave Cambridge to take up a government
position in London becoming Warden of the Royal Mint in 1696 and Master in
1699. However, he did not resign his positions at Cambridge until 1701. As
Master of the Mint, adding the income from his estates, we see that Newton
became a very rich man. For many people a position such as Master of the Mint
would have been treated as simply a reward for their scientific achievements.
Newton did not treat it as such and he made a strong contribution to the work
of the Mint. He led it through the difficult period of recoinage and he was
particularly active in measures to prevent counterfeiting of the coinage.
In 1703 he was elected president of the Royal Society and was
re-elected each year until his death. He was knighted in 1705 by Queen Anne,
the first scientist to be so honoured for his work. However the last portion of
his life was not an easy one, dominated in many ways with the controversy
with Leibniz over which had invented the calculus.
Given the rage that Newton had shown throughout his life when
criticised, it is not surprising that he flew into an irrational temper
directed against Leibniz. We have given details of this controversy
in Leibniz's biography and refer the reader to that article for details.
Perhaps all that is worth relating here is how Newton used his position as
President of the Royal Society. In this capacity he appointed an
"impartial" committee to decide whether he or Leibniz was the
inventor of the calculus. He wrote the official report of the committee
(although of course it did not appear under his name) which was published by
the Royal Society, and he then wrote a review (again anonymously) which
appeared in the Philosophical Transactions of the Royal Society.
Newton's assistant Whiston had seen his rage at first
hand. He wrote:-
Newton was of the most fearful, cautious and suspicious temper
that I ever knew.