As will be evident from this biography, Newton carefully preserved his notebooks and papers, including his correspondence, throughout his life, accumulating a mass of folded bundles whose contents were not in all cases readily identifiable. After his death, as part of the settlement of his intestacy, John and Catherine Conduitt received undivided rights to this great mass. Only two manuscripts (The Chronology of Ancient Kingdoms Amended and The System of the World) were found suitable for immediate sale to booksellers for publication; otherwise little from this mass reached print during the eighteenth century, even in Samuel Horsley's collected edition of Newton's writings (1779–85). While Horsley had been able to make only a cursory examination of the papers and remained unperceptive of their significance, Newton's first real biographer, Sir David Brewster, amended and amplified a book already in proof from biographical (and some other) materials selected for him by Henry Arthur Fellowes in 1837.

Fellowes was a nephew of the then Earl of Portsmouth, owner by inheritance of the Newton papers, which were preserved at his seat, Hurstbourne Park in Hampshire. His family name was Wallop; the younger Catherine Conduitt (Newton's ‘Kitty’) had married John Wallop in 1740, becoming titular Viscountess Lymington by the creation of the earldom of Portsmouth for her father-in-law in 1743.

Meanwhile, before Brewster's time many letters and documents sent by Newton to others (including Collins, Boyle and Locke) had reached print, as had extracts or paraphrases of the memoirs of Newton compiled by John Conduitt before and after Newton's death. Some of these Newtonian scraps have since been rejected as false.

Newton served the State in a variety of capacities for thirty years; he not only embodied in his own person (as Pepys had formerly done at the Admiralty and his contemporary William Lowndes did at the Treasury) a novel conception of the high-ranking, efficient, professional civil servant, but helped to established the character of the English government official in the parliamentary age: as a man of integrity, unremitting in his attention to business, thoroughly competent in matters of detail yet no mere clerk – a head of department able to realize ministerial policy in concrete terms.

As we have seen, Newton's association with government began with his election as a university Member of Parliament for Cambridge in January 1689. After the thirteen months – including a long summer recess – of the Convention Parliament no one at Cambridge seems to have wished to propose Newton for a second term. Two years after his translation to the mastership of the Mint (25 December 1699) he was again nominated and elected Member of Parliament for the university. He is known to have supported Halifax and the Whig Junto on a vote of confidence but was in general no more obvious in the House of Commons than before. When the Parliament was dissolved after a few months (2 July 1702) Newton refused to stand again unless unopposed: ‘To solicit and miss for want of doing it sufficiently, would be a reflection upon me, and it's better to sit still.”

Leibniz and Newton

The link between Britain and G. W. Leibniz, now firmly stationed at Hanover though often travelling about Europe in the interests of his master, was decisively broken by the sudden death of Henry Oldenburg early in September 1677. A last letter from him to Leibniz had advised the philosopher to expect no speedy response to his recent mathematical letters from either Collins or Newton; the silence in fact was to last for fifteen years. Whether or not Newton would have been willing to carry on the correspondence with Leibniz, he lacked easy means to do so. Both Collins and Newton studied Leibniz's letters, however. We have no opinion at this stage about Leibniz's mathematical discoveries from Newton himself, but it would seem that he, Collins and John Wallis agreed that Leibniz had (like James Gregory) made an independent discovery of the ‘method of series’ based on the work of earlier mathematicians which he had developed in his own way, and to which he had added an improved ‘method of tangents’. Collins imagined (mistakenly) that Leibniz had gleaned something from Barrow's lectures, and suggested that the Royal Society might print Leibniz's letters to Oldenburg. He never hinted that Leibniz owed anything to Newton.

As previous chapters have shown, Newton did little to promote his calculus in the twenty years after 1671. Leibniz too gave few signs of his slumbering mathematical genius for eight years after leaving Paris.

Newton's Teaching in Cambridge

The greater part of Newton's original work in mathematics and science was first expressed in the form of university lectures. This is true of his researches in geometrical and experimental optics, of his discoveries in theoretical and celestial mechanics, and of his investigations in algebra and some other parts of mathematics. He never lectured upon calculus, no doubt believing that this topic was far beyond the reach of his student auditors; and he did not lecture either upon his chemical, alchemical, biblical and historical studies, not only for the reason that they lay far outside the scope of his professorship. The details of Newton's lecturing are formally known to us from the manuscripts of his optical lectures (in two versions), of the Arithmetica universalism and of the De motu corporum which he submitted to the University Library in accordance with the statutes of his professorship – or nearly so! These statutes, indeed, required the Lucasian Professor of Mathematics to deliver upwards of twenty lectures in each academic year, neatly written copies of ten of them to be deposited with the vice-chancellor in the following year. But although these statutes had been drawn up only in 1663, when the professorship was founded by Henry Lucas, their provisions were at once disobeyed. While his predecessor, Isaac Barrow, had probably lectured in two terms of each year, Newton went to the Schools in one only, half an hour being reckoned a near enough approach to the statutory ‘about one hour’.

The Reflecting Telescope

The close of the year 1671 was marked by the public appearance of Newton upon the national stage of the Royal Society of London. It is strange that with both Newton and his arch-rival Leibniz this event happened in the same unexpected and unlikely way: each of them presented a gadget to the Royal Society. In Leibniz's case it was an arithmetical machine, a toothed-wheel device of the type pioneered by Blaise Pascal, in Newton's his miniature reflecting telescope. Newton's introduction to the Society (December 1671) preceded Leibniz's by just over a year. Both men were, for their pains, severely mauled by Robert Hooke, with assertions that their inventions were valueless and much inferior to his own schemes. Both were deeply wounded by this reception, though also conscious of the warmer welcome extended to them by other Fellows of the Royal Society, not least its Secretary, Henry Oldenburg.

Newton and Leibniz certainly did not meet during this first visit of Leibniz to London (January–March 1673), though before long Collins would be sharing with Leibniz an outline of the mathematical progress accomplished by James Gregory and Isaac Newton. Yet curiously there may be a link between Leibniz and Newton's reflecting telescope. In a letter that Oldenburg received probably about 20 October 1671, Leibniz (writing about the innovations made by a young German optician) mentioned ‘Tubos Catadioptricos, quales mihi in mentem venerunt’ (‘reflecting-refracting tubes, such as occurred to my mind’). No explanation of this phrase has been found, but Newton had certainly invented a catadioptrical telescope.

Warden of the Mint, 1696

It is a fair guess that Newton was never fully content with his professorial and collegiate life in Cambridge after the university had sent him to Parliament in 1689. Indeed, it may be that his eye began to rove as early as 1687, in the period of lassitude that must inevitably have followed the intense and exciting task of bringing the Principia to a conclusion in the summer of that year. By that time the acquaintance or friendship between Samuel Pepys PRS and Isaac Newton must have been established; besides the Royal Society, Christ's Hospital mathematical school had brought the two men together. Pepys was then at the height of his career and of his influence. At the peak of his psychological crisis in 1693 Newton wrote to Pepys: “I never designed to get anything by your interest, or King James favour,” an obvious allusion to days before the Revolution, after which Pepys's influence was nil. If we may read this anxious denial as evidence that there really was some such talk or manoeuvre (as with Newton's parallel denial to Locke), it must have occurred in 1687 or 1688.

Similarly and in the same disturbed frame of mind, Newton wrote to Locke: “I beg your pardon also for saying or thinking that there was a designe to sell me an office.” In this case, letters do hint at Locke's enlisting the help of the Earl of Monmouth (a favourite of William Ill's and recently First Lord of the Treasury) who had been a patron of Locke himself.

Our society depends upon science, and yet to many of us what scientists do is a mystery. The sciences are not just collections of facts, but are ordered by theory, and this is where Einstein's famous phrase about science being a free creation of the human mind comes in. Science is a fully human activity; the personalities of those who practise it are important in its progress and often interesting to us. Looking at the lives of scientists is a way of bringing science to life.

By the time of his death in 1727 Newton stood as the representative figure of modern science. His name was something to conjure with, evoking ideas of the absent-minded professor, the solitary genius, and the power of mathematical and experimental science to answer questions about the world. He became a key figure in the Enlightenment of the eighteenth century, and his work correspondingly aroused unease among Romantics who saw his science as inhuman and reductive.

A mythical Newton, a new Adam born on Christmas Day and nourished by an apple from the tree of knowledge, came to obscure the real man who had worked in dynamics, astronomy and optics, and less successfully in chemistry, to synthesize the work of great predecessors such as Kepler, Galileo, Descartes and Boyle. Rupert Hall comes to this biography after editing the correspondence of both Newton himself and also Henry Oldenburg, the first secretary of the Royal Society and the editor of its journal. He has also edited some of Newton's unpublished papers.

Newton first took up residence in a house in Jermyn Street (now number 88) towards the socially superior western end, in which he lived four years, then from 1700 to 1709 in the next-door house (87). Sir Robert Gayer was a near neighbour (letter 710). Leases for these properties had been granted by the trustees of the Earl of St Albans in 1665, and the buildings were put up about ten years later. Number 87 is at present undergoing total reconstruction and number 88 is a shop (‘James Bodenham’) with the original brick structure preserved.

After his brief sojourn in Chelsea (where he lived at the east end of Paradise Row) Newton moved to 35 St Martin's Street, a few yards south of Leicester Fields (now Square), an area just newly developed by Lord Leicester. There he lived in a house built c.1695 from 1711 to 1725. It had three storeys with basement and was built of brick with a tiled roof; there was a bracketed hood over the front door. On the main floors were rooms front and back with a projecting ‘closet’ wing at the rear. The ground-floor front room was panelled. According to a footnote in the Survey of London Newton had a small observatory built at the top of the house.

In Kensington he lived (in lodgings?) in Orbell's Buildings, a little north of Kensington High Street and west of Church Street, a site now occupied by Bullingham Mansions. He already owned property south of the High Street.

Newton was painted at least seventeen times by seven or more artists: Sir Godfrey Kneller depicted him four times, Sir James Thornhill and John Vanderbank twice. In addition one may examine a death mask, ivory medallions made by David Le Marchand at various dates and an excellent medal in profile (1726) by Newton's Mint artist, John Croker. All these images of Newton, except the 1689 Kneller (of which at least two versions exist) were made after Newton's move to London, hence after the age of sixty (Kneller, 1702). Many of the portraits were engraved and widely circulated.

Three of especial interest are the 1689 Kneller painting of Newton with a youthful, alert, intellectual appearance, of which the original has always been in the family; the 1720 Kneller painted for Pierre Varignon; and the 1725 Vanderbank, commissioned by the Royal Society and still hanging in its rooms.

Of the second, showing Newton at the age of seventy-eight, Varignon remarked that he appeared no more than fifty years old, yet Brook Taylor had assured him of its excellence as a likeness. Stukeley, present at the ‘sittings’ for this portrait, wrote that ‘it was no little entertainment to hear the discourse that passed between these two first men in their way. tho it was Sir Isaac's temper to say little, yet it was one of Sir Godfrey's arts to keep up a perpetual discourse, to preserve the lines and spirit of a face’ (Memoirs, 1936, pp. 12–13). This portrait was later acquired in Paris by Lord Egremont and now hangs at Petworth.

When his work ceased, the story of Newton's life ended. William Stukeley and John Conduitt – the latter in a memoir sent to Fontenelle, then writing his éloge of Newton as a membre étranger of the Académie Royale des Sciences – agree that his decay began with ‘a relaxation of the sphincter of the bladder; so that he was oblig'd to make water frequently’. Newton curtailed his social life and dined simply: ‘chiefly upon broth, vegetables, and fruit, of which he ate very heartily’. This was about 1722. In August 1724 he passed a bladder-stone, without much pain, and in the following winter suffered bronchitis (or worse). Temporarily, he was much improved in general health by moving out to the village of Kensington, in country air, though he suffered an attack of gout. Through two good years he worked on the third Principia with Pemberton. It was on 7 March 1725 that he had a ‘curious conversation’ with Conduitt about his notion of a secular revolution in the cosmos, whereby matter from the Sun was condensed into bodies, becoming planets, then comets which ultimately fall into the Sun, and so falling may destroy the Earth by fuelling the Sun to excessive heat. Man's duration on Earth Newton took to be brief: for all arts and sciences had been discovered ‘within the memory of history, which could not have happened, if the world had been eternal; and … there were visible marks of ruin upon it which could not be effected by a flood alone.’

Hooke and Newton, 1679–80

Recently D. T. Whiteside has published an authoritative article on the evolution of the Principia from 1664 to 1686, following hard upon a large volume of facsimiles of the relevant documents. My account here, therefore, may be confined to bare essentials, especially as so little is known of Newton's personal life in the period of most intense effort devoted to his great work, that is, from the summer of 1684 to the late spring of 1686, when his surviving correspondence with Edmond Halley opens. Of the dozen extant letters from this period of some twenty-six months, no fewer than nine concern Flamsteed's putative provision of astronomical data for use in the Principia.

We must go back to chapter 6, where we left Robert Hooke enticing Newton (against his desire) into a philosophical correspondence. In a rejoinder of 9 December Hooke returned to Newton's carelessly considered spiral of descent, ending at the centre of the globe, as sketched in his letter to Hooke of 28 November 1679 (see figure 6.1). Regretting Newton's renunciation of philosophy as ‘a little Unkind’ and disclosing that he had read Newton's reply to his first approach at a meeting of the Royal Society, Hooke agreed, as had other Fellows then present, that a weight would fall to the east of its point of departure, not the west.

“The same year I found the method of Tangents …”

The origins of Newton's principal innovations in mathematics and science are to be found in the records of his reading as an undergraduate; immediately after these studies came “the prime of my age for invention” which Newton placed in 1665 and 1666. In mathematics and optics the transition from reading to original investigation can be perceived (though not exactly dated). In mechanics, on the other hand, we find Newton's earliest discovery on the first page of his “Waste Book” (Cambridge University Library MS Add. 4004), where the tenth page is dated “Jan 20th 1664” (that is, 1665 in our reckoning). No known annotation from Galileo or any other likely source antedates the “Waste Book”. From this and other dates in the notebooks it is evident that Newton's great epoch of creative scientific work began some months before the start of the year 1665, while he continued to mine the rich veins that he had opened as late as (probably) 1668. The two years of Newton's reminiscences stretch more accurately to three or more, of which 1665 and 1666 were central and critical.

That a large portion of this creative epoch was passed in Lincolnshire – not by any means altogether at home in Woolsthorpe, but probably also at Grantham and certainly at Boothby Pagnell – was a matter of chance. Not for the first time, Cambridge University was closed by plague. Bubonic plague had been endemic in Britain since the great pandemic of the mid-fourteenth century; the last major outbreak had been in 1625.

The Queries in Opticks

The last quarter of Newton's life was distinguished from the first three-quarters by the profusion of his written work that was published by himself or by others for him. As always with Newton, none of this publication was fundamentally new: his intellectual effort was devoted to making more perfect what had been published before (as with the Principia and Opticks), to bringing to light from his files writings and correspondence of long ago (as with Commercium Epistolicum), or to polishing for the benefit of posterity the results of studies that he had pursued for decades (as with The Chronology of Ancient Kingdoms Amended and The Prophecies of Daniel and John). In making this point I do not mean quite to assert that, had Newton died in 1705, it would have been possible to reconstruct from his papers all that was subsequently published under his name. Only of the posthumous System of the World would this be exactly true. On most of the late books Newton was always at work, modifying, adding new material from experiments and reading, extending and revising.

Of the Queries appended to the successive editions of Opticks this is particularly true. The main text of this book was not greatly changed when it was republished in Latin in 1706, nor indeed in the subsequent English editions. The Queries, however, developed into the most important series of statements that Newton released to the public about the deepest questions of natural philosophy: the concepts of matter and force, the possible role of an aether and the relation of God to the universe.

On the first of March, 1704, David Gregory noted in his diary that Newton had been ‘provoked by Dr Cheyns book to publish his Quadratures, and with it, his Light & Colours, &c.’ And just one month later Newton indeed signed and dated his “Advertisement” to this volume. Some sixteen months had passed since he had promised ‘Mr [Francis] Robarts, Mr Fatio, Capt. Hally & me to publish his Quadratures, his Treatise of Light, and his treatise of the curves of the 2d Genre [sic]’. In the interval Robert Hooke had died, thus clearing the way for the publication of Opticks,a book which Newton had sworn to keep to himself so long as Hooke lived. Opticks, like the pair of mathematical treatises that was to appear with it, had been long anticipated by Newton's friends. In 1694 Gregory had examined its three Books – hence it was substantially complete then, though Newton was not yet ‘fully satisfied about a certain kind of colours and the way of producing it’ – and summarized it in his diary of his visit to Cambridge (5 to 7 May). Newton meant to publish it after leaving the university, in English as it was written, or translated into Latin if he remained at Cambridge. By April 1695 John Wallis at Oxford knew of it (through Flamsteed's protégé Caswell) as ‘a Treatise about Light, Refraction and Colours’ already completed. ‘Tis pitty it was not out long since. If it be in English (as I hear it is) let it, however, come out as it is; & let those who desire to read it, learn English.’ Thus spoke this fervid Englishman! Through successive letters Wallis continued to prod Newton, but he would not budge.

The Master of Arts

After looking so far forward to the origins of the Principia, it comes almost as a shock to realize that young Isaac Newton was still barely twenty-four years old, not yet a Master of Arts, when he returned to Cambridge in 1667. It would be strange indeed if he were not now far more conscious of his own potentiality in the world of learning than he had been before the plague. Five years into the future he would be arguing for his own discoveries on equal terms with the acknowledged leaders of the scientific movement in Europe. As yet, however, he stood on the lowest rung of the ladder of academic promise and his name was unknown. Newton had a chance of a minor fellowship at Trinity College at the next election, in the coming October, and no doubt hoped for something from the support of his family connection, Humphrey Babington. Candidates for the fellowship had to submit, at least in theory, to four days of oral examination by the Seniors in the college chapel. By whatever means, and whoever was convinced of his merits, Newton was indeed among the chosen. He was assigned the ‘Spiritual Chamber’ to reside in, but probably remained where he was with his friend (and amanuensis) John Wickins, renting out the room allotted to him. Trinity College now paid him ‘wages’ of £2 per annum, gave him allowances for livery and commons (that is, clothing and food) and allowed him his share (‘dividend’) of the college revenues. Trinity also assigned him his first pupil, a Fellow-commoner named St Leger Scroope, who made no mark in history.