LOOKING back from the beginning of 1666, one finds it difficult to believe that Newton touched anything but mathematics during the preceding eighteen months. Clearly mathematics did dominate his attention during the period, but it did not completely obliterate other interests. Sometime during this period he also found time to compose the “Quaestiones,” in which he digested current natural philosophy as efficiently as he did mathematics. Other natural philosophers were as ignorant of his existence as mathematicians were. To those who knew of him, his fellow students in Trinity, he was an enigma. The first blossoms of his genius flowered in private, observed silently by his own eyes alone in the years 1664 to 1666, his anni mirabiles.

In addition to mathematics and natural philosophy, the university also made certain demands on his time and attention. He was scheduled to commence Bachelor of Arts in 1665, and regulations demanded that he devote the Lent term to the practice of standing in quadragesima. Pictured in our imagination, the scene has a surrealistic quality, medieval disputations juxtaposed with the birth pains of the calculus. An investigation of curvature was dated 20 February 1665, in the middle of the quadragesimal exercises, and in his various accounts of his mathematical development he assigned the binomial expansion to the winter between 1664 and 1665. While Stukeley was a student in Cambridge over thirty years later, he heard that when Newton stood for his B.A. degree, “he was put to second posing, or lost his groats as they term it, which is look'd upon as disgraceful.”

POSSIBLY the fact that the university closed down for the better part of two years, freeing Newton from control and supervision, aided his unorthodox program of study. Such was the progressive decomposition of the established curriculum, however, that it is far from clear that his intellectual development would have differed in any respect had the plague not intervened. While the requirements prescribed an impressive array of lectures, disputations, and acts over a three-year period before a Bachelor of Arts might be admitted as an inceptor for the Master of Arts degree, most of them had ceased to be operative by the Restoration, as repeated orders from Westminster that they be observed testify. Even residence had ceased to be required. Though Newton himself was not frequently absent from Cambridge once he returned after the plague, the college Exit and Redit Book reveals that other scholars of the house felt free to come and go as they pleased, even in term time. Newton's friend Wickins, for example, who was a scholar drawing a stipend, left the college on 15 October 1667 and did not return until the middle of January. Unorthodox study was not manifestly worse than no study at all. The one discipline exerted was financial; Newton received his stipends through his tutor. Although his papers do not indicate that he again made any gestures whatever toward the established curriculum, his academic career nevertheless marched through the remaining stages to full membership in the college and university without hesitation.

NEWTON'S repeated protestation that he was engaged in other studies supplied an ever-present theme to his correspondence of the 1670s. Already in July 1672, only six months after the Royal Society discovered him as a man supremely skilled in optics, he wrote to Oldenburg that he doubted he would make further trials with telescopes, “being desirous to prosecute some other subjects.” Three and a half years later, he put off the composition of a general treatise on colors because of unspecified obligations and some “buisines of my own wch at present almost take up my time & thoughts.” Apparently the other business was not mathematics, because later in 1676 he hoped the second letter for Leibniz would be the last. “For having other things in my head, it proves an unwelcome interruption to me to be at this time put upon considering these things.” He was not only preoccupied, he was almost frantic in his impatience. “Sr,” he concluded the letter, “I am in great hast, Yours …” In great haste because of what? Surely not because of ten lectures on algebra that he purportedly delivered in 1676. And not because of pupils or collegial duties, for he had none of either. Only the pursuit of Truth could so drive Newton to distraction that he resented the interruption a letter offered. Newton was in a state of ecstasy again.

WELL before the contested edition of Flamsteed's Historia coelestis in 1712 brought that episode to a temporary conclusion, two new concerns, which would dominate Newton's life for more than five years, had imposed themselves upon him. In 1709, work began in earnest on a second edition of the Principia. In the spring of 1711, a letter from Leibniz to Hans Sloane, secretary of the Royal Society, inaugurated a heated controversy over claims of priority in the invention of the calculus. Moreover, a fourth problem of great import for Newton was also taking form. Already an ugly scene with Craven Peyton, the warden of the Mint, had signaled a deterioration of their relations which culminated in a major crisis in the Mint in 1714, when the battle with Leibniz was reaching its highest pitch. The Mint was the bedrock on which Newton's existence in London stood. Trouble there had to affect his whole life. In its intensity, the period from 1711 to 1716, succeeding more than a decade of relative calm, matched the great periods of stress at Cambridge, when his relentless pursuit of truth stretched him to the limit. The coincidence of these events, the demands they placed on Newton, may help to explain the furious scene with Flamsteed at Crane Court on 26 October 1711 and much else from these years not yet mentioned.

THE utility of biography, Dr. Johnson argued, rests on the fact that we can enter by sympathy into situations in which others have found themselves. Parallel circumstances to which we can conform our minds shape every life. Even the great are not removed from the factors common to all: “We are all prompted by the same motives, all deceived by the same fallacies, all animated by hope, obstructed by danger, entangled by desire, and seduced by pleasure.” I must confess that twenty years devoted to the biography of Newton have not in my case confirmed Dr. Johnson's dictum. The more I have studied him, the more Newton has receded from me. It has been my privilege at various times to know a number of brilliant men, men whom I acknowledge without hesitation to be my intellectual superiors. I have never, however, met one against whom I was unwilling to measure myself, so that it seemed reasonable to say that 1 was half as able as the person in question, or a third or a fourth, but in every case a finite fraction. The end result of my study of Newton has served to convince me that with him there is no measure. He has become for me wholly other, one of the tiny handful of supreme geniuses who have shaped the categories of the human intellect, a man not finally reducible to the criteria by which we comprehend our fellow beings, those parallel circumstances of Dr. Johnson.

NEWTON set out for Cambridge early in June. There was no greater watershed in his life. Although he would return to Woolsthorpe infrequently during the next eighteen years, with two extended visits during the plague, spiritually he now left it, and what a later commentator has called the idiocy of rural life, once and for all. Three short years would put him beyond any possibility of return, though three more years, perhaps somewhat longer, had to pass before a permanent stay in Cambridge was assured. His accounts show that he stopped at Sewstern, presumably to check on his property there; and after spending a second night at Stilton as he skirted the Great Fens, he arrived at Cambridge on the fourth of June and presented himself at Trinity College the following day. If the procedures set forth in the statutes were followed, the senior dean and the head lecturer of the college examined him to determine if he was fit to hear lectures. He was admitted – although there is no record whatever of anything but the verdict, one feels constrained to add “forthwith.” He purchased a lock for his desk, a quart bottle and ink to fill it, a notebook, a pound of candles, and a chamber pot, and was ready for whatever Cambridge might offer.

NOT a great deal of time has passed since I wrote a preface for the first printing of this book, and with that preface brought more than twenty years of work to a conclusion. After such a period I was, I confess, ready to move on to other matters, and with the exception of one Newtonian topic, I have done so. As a result I am not now prepared or inclined to revise the work in any fundamental way. Beyond correcting a few typographical and factual errors, I confine myself to indicating here some passages that reviews and recent publications have convinced me ought to be altered, and to mentioning the one topic on which my own research since completing the biography has led me to a deeper understanding.

In Chapter 2, pp. 57–58, I assert that Newton's secondary education did not include any significant mathematics. Recently, D. T. Whiteside has uncovered in Grantham a pocketbook dated 1654 that contains extensive “Notes for the Mathematicks.” [See “Newton the Mathematician,” in Z. Bechler, ed., Contemporary Newtonian Research (Dordrecht, 1982), pp. 110–11.] It appears to Whiteside to have been written in the hand of Henry Stokes, master of the grammar school of Grantham, which Newton began to attend during the year following the notes. Although most of the passage is devoted to elementary calculations, such as rules for determining the areas of fields, that a country gentleman might have found useful, not all of it remains at this level.

BY the end of 1676, as absorbed in theology and alchemy as he was distracted by correspondence and criticism on optics and mathematics, Newton had virtually cut himself off from the scientific community. Oldenburg died in September 1677, not having heard from Newton for more than half a year. Newton terminated his exchange with Collins by the blunt expedient of not writing. It took him another year to conclude the correspondence on optics, but by the middle of 1678, he succeeded. As nearly as he could, he had reversed the policy of public communication that he began with his letter to Collins in 1670 and retreated to the quiet of his academic sanctuary. He did not emerge for nearly a decade.

Humphrey Newton sketched a few facets of Newton's life as he found it in the 1680s. Newton enjoyed taking a turn in his garden about which he was “very Curious … not enduring to see a weed in it …” His curiosity did not rise to the level of dirtying his hands, however; he hired a gardener to do the work. He was careless with money; he kept a box filled with guineas, as many as a thousand, Humphrey thought, by the window. Humphrey was not sure if it was carelessness or a deliberate ploy to test the honesty of others–primarily Humphrey. In the winter, he loved apples, and sometimes he would have a small roasted quince.

THE paper on colors that Newton sent to the Royal Society early in 1672 in the form of a letter addressed to Henry Oldenburg did not contain anything new from Newton's point of view. The occasion provided by the telescope had come at an opportune time. At Barrow's behest, Newton had been revising his lectures for publication during the winter. He had not found it a great chore to produce a succinct statement of his theory buttressed by three prismatic experiments that he took to be most compelling. He thought it relevant to include a special discussion of how the discovery had led him to devise the reflecting telescope. The continuing correspondence provoked by the initial paper, which intruded intermittently on his time and consciousness during the following six years, also involved only one addition to his optics, his introduction to diffraction and brief investigation of it. Aside from diffraction, the entire thrust of his concern with optics during the period was the exposition of a theory already elaborated.

The continuing discussion forced Newton to clarify some issues. When he wrote in 1672, he had not yet fully separated the issue of heterogeneity from his corpuscular conception of light, and he allowed himself to assert that, because of his discovery, it could “be no longer disputed … whether Light be a Body.” He could hardly have been more mistaken.

IN his age of celebrity, Newton was asked how he had discovered the law of universal gravitation. “By thinking on it continually,” was the reply. No better characterization of the man can be given, not only in its delineation of a life whose central adventure lay in the world of thought rather than action, but also in its description of his mode of work. Seen from afar, Newton's intellectual life appears unimaginably rich. He embraced nothing less than the whole of natural philosophy, which he explored from several vantage points which ranged all the way from mathematical physics to alchemy. Within natural philosophy, he gave new direction to optics, mechanics, and celestial dynamics, and he invented the mathematical tool which has enabled modern science further to explore the paths he first blazed. He sought as well to plumb the mind of God and His eternal plan for the world and mankind as it was presented in the biblical prophecies. When we examine Newton's grandiose adventure minutely, it curns out to be a mixture of discrete pieces rather than a homogeneous melange. His career was episodic. What he thought on, he thought on continually, which is to say exclusively, or nearly exclusively. What seized his attention in 1664, to the virtual exclusion of everything else, was mathematics.

ISAAC Newton was born eighteen and a half years before he entered Cambridge, early on Christmas Day 1642, in the manor house of Woolsthorpe near the village of Colsterworth, seven miles south of Grantham in Lincolnshire. Since Galileo, on whose discoveries much of Newton's own career in science would squarely rest, had died that year, a significance attaches itself to 1642. I am far from the first to note it – and will be undoubtedly far from the last. Born in 1564, Galileo had lived nearly to eighty. Newton would live nearly to eighty-five. Between them they virtually spanned the entire scientific revolution, the central core of which their combined work constituted. In fact, only England's stiff-necked Protestantism permitted the chronological liaison. Because it considered that popery had fatally contaminated the Gregorian calendar, England was ten days out of phase with the Continent, where it was 4 January 1643 the day Newton was born. We can sacrifice the symbol without losing anything of substance. It matters only that he was born and at such a time that he could utilize Galileo's work.

Prior to Isaac, the Newton family was wholly without distinction and wholly without learning. Since it knew steady economic advance during the century prior to Isaac's birth, we may assume that it was not without diligence and not without the intelligence that can make diligence fruitful.

NEWTON'S name in the matriculation book of Cambridge University on 8 July 1661, together with those of sixteen other students recently admitted to Trinity College, bears witness to an event so obviously significant in his life (as it must have been for the other sixteen, and as similiar events have been for countless young men through eight centuries of Western history) that one flirts with banality even to mention it. He had left his home in the hamlet of Woolsthorpe in Lincolnshire some five weeks earlier, a raw provincial youth venturing more than ten miles from the place of his birth probably for the first time. He had been admitted to Trinity College on 5 June. As it turned out, the change in scene involved much more than the inevitable shattering of rural provincialism. In Cambridge, Newton discovered a new world. In one sense, of course, every youth who truly enters a university discovers a new world; such is the process of education, the opening of fresh horizons. Newton discovered a new world in a more concrete sense of the phrase, however. By 1661, the radical restructuring of natural philosophy that is called the scientific revolution was well advanced. Behind the familiar facade of nature, philosophers – we would call them scientists – had indeed discovered a new world, a quantitative world instead of the qualitative world of daily experience, mechanistic instead of organic, indefinite in extent instead of finite, an alien world frightening to many but in its challenge thrilling to some.

NEWTON was hardly an unknown man in philosophic circles before 1687. The very extent to which he had made his capacity in physics and mathematics known had functioned in the early 1680s to destroy his attempt to reconstruct an isolation in which he might pursue his own interests in his own way. Nevertheless, nothing had prepared the world of natural philosophy for the Principia. The growing astonishment of Edmond Halley as he read successive versions of the work repeated itself innumerable times in single installments. Almost from the moment of its publication, even those who refused to accept its central concept of action at a distance recognized the Principia as an epoch-making book. A turning point for Newton, who, after twenty years of abandoned investigations, had finally followed an undertaking to completion, the Principia also became a turning point for natural philosophy. It was impossible that Newton's life could return to its former course.

Rumors of the coming masterpiece had flowed through Britain during the first half of 1687. In Scotland, David Gregory held up the publication of a method of quadratures until he saw if Newton printed his method in the Principia. It was a judicious precaution on Gregory's part, since he had only recently plagiarized the method from the notes that John Craig had brought home from Cambridge in 1685. When the young Swiss mathematician, Nicolas Fatio de Duillier, arrived in London in the spring, he found intellectual circles aflutter with expectation of the book which would, he was assured, remodel natural philosophy.

THE Royal Society, to which Newton had dedicated his Principia in 1687 only to ignore it steadfastly when he moved to London, stood at a low ebb during the early years of his residence in the capital city. Membership, which had reached more than two hundred in the early years of the 1670s, now scarcely numbered more than half that figure, and few of the members attended the weekly meetings. In light of what the minutes indicate about the meetings, one cannot blame them for not attending. Unplanned and unstructured, given over mostly to miscellaneous chit-chat devoid of serious scientific interest, the meetings suggested little of the interests that had brought the society together forty years earlier. In 1699, a concerned council gave thought to stimulate members to perform experiments at meetings. On 8 March, they drew up a list of thirty-eight members (including “Mr. Newtoun”) who might be charged with that function, and a week later seventeen of them (“Mr. Newtoun” not included) showed up at the council and promised to undertake the obligation. The following week, some of the seventeen suggested that the council pay them £5 per year for their pains.

The flurry of interest died out as quickly as it had arisen, however, and later that spring Mr. Van de Bemde's remark “yt cows piss drank to about a pint, will either purge or vomit with great Ease,” led to an all-too-typical discussion of the medicinal value of bovine urine.