FOR JOHN LOCKE, 1691 had been a busy year. He had left London for an open-ended stay at a friend's country house in Essex, and he had completed another book, one of his first since A Letter Concerning Toleration, his famous argument for freedom of conscience and belief. The new work took on a completely different though equally contentious topic: what to do about England's growing financial crisis, brought on by the plague of bad coins. After sending friends copies of the new manuscript in early December, he found himself free of immediate duties. So, at leisure at last, he resumed one of the hobbies of his youth.
Just before nine o'clock on the morning of Sunday, December 13, he left his rooms upstairs, overlooking the garden, and hurried outside to record his daily observations of the weather. His thermometer was a good one, produced by the celebrated London watchmaker Thomas Tompion. Locke recorded the temperature: 3.4 on the particular scale used on his instrument—notably colder than the "temperate" reading of 4, but not quite as cold as the day before, when Locke noted frost. This day, he found that the barometric pressure had dropped overnight and a light breeze had set in from the east. Last, he recorded the condition of the sky: thick, uniform clouds. In other words, a typical December day in the east of England: chilly, damp, and dull.
That same day, about thirty miles to the north, Isaac Newton, in a state of annoyance, began a letter. He drew out a sheet of paper, loaded his quill with ink, and began to write. He filled a page, read it, and paused. Newton was swift to take offense, and as Robert Hooke had already learned to his sorrow, Newton's enemies had to expect overwhelming retaliation for any slight, real or imagined. But today's missive was directed against that amateur meteorologist John Locke, a man whom Newton admired and by whom he was admired in turn. Newton found it difficult to strike the right note of reproach.
The crime in question? Locke had offered to help his friend Newton gain the post of Master of Charterhouse, a boys' school in London. Newton recoiled at the thought. "You seem still to think on Charterhouse," he wrote, but "I believe your notions & mine are very different about the matter." What was wrong with the proposal? Everything. "The competition is hazzardous," he complained, "and I am loathe to sing a new song" in hopes of persuading the mighty to throw him a sop. Still more galling, the pay was meager, beneath him. "Its but 200 pounds per an besides a Coach (wch I reccon not) & lodging"—not enough to live in the style to which Newton aspired nor fit reward for a man of his reputation.
And, of course, there was the problem of London.
Newton had lived in Cambridge for thirty years. All the decades of thought and labor that had transformed an awkward country boy into the dominant mind in Europe had taken place in and around the rooms overlooking the Great Court and chapel of Trinity College, from which he now wrote angrily to his friend. And yet Locke dared to suggest that he should abandon Cambridge for London, with all its filth and pretense. How could Newton express the manifold unsuitability of the suggestion? Try this: "The confinement to ye London air & a formal way of life is what I am not fond of."
Line after line expressed his sense of insult—and then he stopped. His rage cooled. He did not sign the letter.
The truth was that Newton desperately hoped to escape his intellectual cloister, and just as desperately desired the exceptionally well-connected Locke's help to do so. What had happened?
The Principia had, and with it Newton's sudden emergence into the circles of the great.
From the moment of its publication—and before, in fact—Edmond Halley had done his best to make sure that the Principia received its proper reception. He launched his campaign on the first pages of the work itself, adding to Newton's text a dedicatory ode: "Error and doubt no longer encumber us with mist; /...We are now admitted to the banquets of the Gods; / We may deal with laws of heaven above; and we now have / The secret keys to unlock the obscure earth." And, lest anyone mistake the value of the man who had found the keys to the kingdom, Halley concluded: "Join me in singing the praises of newton, who reveals all this /...No closer to the gods can any mortal rise." More soberly, in his formal review Halley argued for Newton's unique significance. "This incomparable author having at length been prevailed upon to appear in publick, has in this treatise given a most notable extent of the powers of the Mind." This Newton was the new Moses, a prophet revealing the law to the people: he had "at once shewn what are the principles of Natural Philosophy and so far derived from their consequences that he seems to have ... left little to be done by those that shall succeed him."
Newton could, of course, count on Halley's praise. The reaction that truly mattered would come from the rest of learned Europe. Over the summer and into the autumn of 1687 those responses came in. Acta Eruditorum, Europe's leading scientific journal, called the book "an investigation worthy of so great a mathematician." In Paris, the devout Cartesian who reviewed the Principia for Le Journal des sçavans wanted an account of gravity that would reveal the mechanism by which one object attracted another, the kind of direct connection required by orthodox mechanical philosophers. The Principia's purely mathematical description of gravity emphatically did not supply that kind of explanation, relying instead on the seemingly occult notion of forces acting across space—but the French reviewer still conceded that "it is not possible to make demonstrations more precise than those which [Newton] gives." The then-anonymous Scottish mathematician David Gregory wrote to Newton, offering "my most hearty thanks for having been at the pains to teach the world that which I never expected any man should have knowne." And though "your book is of so transcendent fineness and use that few will understand it," he stressed his awe on behalf of "those few who cannot but be infinitely thankful to you." Gottfried Leibniz was one of that little band who could indeed comprehend the work. His praise came in the most revealing form: in the winter of 1688–89 he rushed into print three articles that suggested he had either earlier arrived at or refuted some of Newton's conclusions. Such attempted theft acknowledged the obvious: the Principia had become the measure of all scientific excellence from the moment it appeared in print.
From there, it did not take long for Newton's fame to reach the next level. After discussing parts of the Principia, the French philosopher Marquis de l'Hospital burst out, "Good god what fund of knowledge there is in that book!" And then he pressed his companion, an acquaintance of Newton's, for "every particular of Sr I. even to the color of his hair [and]...does he eat and drink & sleep?" Then the Marquis asked the iconic question, the one that has chased Newton ever since: "Is he like other men?"
Newton had entered a realm of fame that catapulted him out of the narrow company of natural philosophers and into the wide world. One of the most worldly to fall into his orbit was an expatriate English man of letters living in the Netherlands—that genteel revolutionary John Locke. Late in 1687 Locke heard of a new book that was causing a sensation. He borrowed a copy from his friend Christiaan Huygens. But when Locke tried to read it, he found himself adrift in Newton's calculations. So he asked Huygens—after Newton the most important scientific thinker of the day—whether he could accept the Principia's technical arguments on faith, simply assuming their validity. Huygens confirmed that Newton had proved what he had claimed, and so Locke read on, taking each mathematical conclusion for granted.
He was enthralled. He wrote one of the early, influential reviews of the book in 1688, in the Bibliothèque universelle, and he made sure his English readers took the point, writing in the preface to his Essay on Human Understanding in 1689 that "the commonwealth of learning is not at this time without masterbuilders, whose mighty designs, in advancing the sciences, will leave lasting monuments." Chief among them "the incomparable Mr. Newton." The critical Newtonian advance, Locke wrote, was that "we might in time hope to be furnished with more true and certain Knowledge in several parts of this stupendous Machine [Nature] than hitherto we could have expected."
Locke was eager to meet any man who had devised the path to such certain truth. There was just one problem: in 1687 he was a political exile, a wanted enemy of the English state. Four years before, Locke, thanks to his long association with King Charles Il's Whig enemies, had been under routine surveillance by agents of the Crown when the Rye House Plot broke. The Rye House conspirators had planned to assassinate the King and his brother James, and the collapse of the scheme led to a wider roundup of the usual suspects. Several prominent Whigs were brought to trial and sent to the scaffold, and Locke himself faced arrest and possible execution for his guilt by association with one of the leading conspirators. Sensibly, he began to move around England and then fled the country altogether, reaching the Netherlands in September 1683. As long as the Stuarts remained in power, there he was compelled to remain.
Newton had his own troubles with his king. When James took the throne after his brother's death in 1685, he began an inept effort to re-Catholicize Protestant England. In 1687, James took aim at Cambridge University, ordering it to grant Father Alban Francis, a Benedictine monk, the degree of master of arts—an honor that would permit Francis to take an official position in the governance of the university. The university's leaders refused, and Newton applauded. He broke into the last weeks of work on the Principia to argue that a "mixture of Papist & Protestants in ye same University can neither subsist happily nor long together." When King James's Court of the Ecclesiastical Commission ordered the university to send representatives to account for its disobedience to the Crown, Newton was selected as a member of the delegation.
The court threatened and blustered. Newton led his colleagues as they pushed back. The government flinched first. In May 1687 the chief judge of the commission issued his order: the Cambridge delegation should "Go your way, and sin no more." Where it counted, Newton and his colleagues had won: Cambridge never granted the required degree.
This victory made Newton a marked man, at least as far as King James was concerned. He returned to Cambridge and, prudently, kept mostly to himself. The fame that the Principia brought him was sweet, but for the moment it remained too dangerous to attempt to savor much of celebrity's rewards.
King James II was a failure at most of the arts of governance. He was, however, a master at enraging his enemies and estranging his friends. It took him just three years on the throne to alienate a critical mass of his subjects. By mid-1688, the traditionally pro-monarchy Tories and their opponents, the Whigs, were both conspiring to replace James with his nephew and son-in-law William, Prince of Orange, whose wife was the King's elder daughter, Mary. In November, William landed on the south coast of England with an army of between eighteen and twenty thousand men (including about two hundred black soldiers recruited—or acquired—from plantations in the American colonies). James was able to counter with a force of about the same size and gathered his army at Salisbury, blocking William's path to London, but the royalist strength drained away as first James's generals and then his own daughter Anne defected to William's side. After a couple of minor skirmishes, James ran. He fled London on December 9 and, a week later, surrendered to a Dutch detachment. Two weeks later, William turned a blind eye as his father-in-law escaped to France.
To give his seizure of power its necessary veneer of legitimacy, William summoned a Convention Parliament to settle the question of the royal succession. Cambridge University had two representatives at the assembly. One of them was that newly declared anti-Catholic Isaac Newton.
It cannot be said that Newton was much of a parliamentarian. There is no record of any speech he might have made in the Convention Parliament; his only documented statement on any matter during his year in the House of Commons was a request to a servant to close a window against a draft. No matter, he did what his constituency expected of him, voting with the majority on February 5, 1689, to declare the throne of England vacant by virtue of James's abandoning it, and to offer the unoccupied monarchy jointly to William and Mary.
With that, Newton found himself free to enjoy something genuinely new in his experience: being lionized by the good and the great. He accepted homage from the members of the Royal Society. Christiaan Huygens arranged to meet him and introduced him to the exalted circles at Hampton Court, where Huygens's brother was part of William's retinue. Locke's friend the Earl of Pembroke welcomed him into his home. Newton dined and drank in company that lauded him as the wisest of men and a member of the winning side in what its victors were already calling the Glorious Revolution.
Newton first encountered John Locke as one of those admirers toward the end of 1689, but the two men swiftly formed a bond of deep affection that lasted, with one significant break, until Locke's death in 1704. In most ways, the two men could hardly have been less similar. The reclusive Newton made few friends, and he was a prude—he once dismissed a companion from his acquaintance for telling a lewd joke about a nun. In contrast, Locke played politics at the highest level, lived in the houses of the rich, enjoyed conversation, and took pleasure in the company of women. He was an amiable flirt among wives of repute, addressing one of his great passions, Lady Damaris Masham, as his "Governess."
Nonetheless, the two men did have some connections to each other, notably through Robert Boyle, the pioneering chemist and unofficial leader of London's philosophical circles. Newton knew Boyle as a professional colleague, one of the few he genuinely admired. Locke's connection was more intimate: in the 1660s, still in his twenties and newly qualified as a medical doctor, Locke found in Boyle a kind of intellectual patron and adviser.
The links spread from there. For several years, Boyle had employed as his assistant another young man, the poor but brilliant Robert Hooke. With Boyle's help, Hooke made his way into the center of English science. The Royal Society, founded in 1660, was initially merely a talking shop, in desperate need (so at least some members believed) of someone who would actually do some practical research. In 1662, with Boyle's support, Hooke became the society's first curator of experiments, charged with offering demonstrations three or four times a week. The next year, the society added to Hooke's duties, asking him to keep a daily record of London's weather. Hooke responded with a characteristically effervescent burst of creation, inventing or improving the basic suite of weather instruments: the thermometer, the barometer, rain and wind gauges, and other, more specialized devices. With those instruments in hand, he began to keep his own weather record. Then the thought occurred to him: how glorious it would be if gentlemen of England rose from their beds and made similar observations all over the country, building a picture not just of local conditions but of the varieties of climate throughout the realm.
Hooke published his meteorological call to arms in the journal of the Royal Society, emphasizing the need for rigor: data had to be taken at the same time every day, using instruments whose properties were known and carefully recorded. Robert Boyle thought this a brilliant idea, and he advised his young friend John Locke to enlist in Hooke's crusade.
Locke signed on, devotedly measuring wind speeds, checking temperatures, gauging cloud cover. Doing so, he became, in effect, a foot soldier in what he and his contemporaries understood to be a radically new approach to knowledge. We now call this transformation the scientific revolution, and it is often imagined as a series of heroic battles, victories in a war against ignorance led by men whose names resound like those of triumphant generals—Copernicus, Kepler, Galileo, Descartes, and Newton, the greatest of them all.
But in fact, the shift in understanding that such men led was carried forward through the daily actions of hundreds, then thousands of people who for pleasure, profit, or both set out to use reason and experimentation to order their surroundings. Practical rationalists such as Jethro Tull and his disciples tried to bring the methods of the new natural philosophy to bear on the farm. Amateur naturalists catalogued the habits of animals painstakingly observed over days, weeks, months. One of the more famous among them was Erasmus Darwin; born four years after Newton's death, he absorbed the Newtonian credo that material events must have discernible material causes, and he grappled with the question of the origin of species that his grandson Charles would solve a century later.
England's sailors measured tides, and traders upholding the power of the Crown across the oceans learned mathematics and developed precision tools to measure the motions of the stars and planets. Instrument makers began to establish the crucial idea of standards, common measures that would enable observers anywhere to trust one another's results. Thomas Tompion, the maker of Locke's thermometer, was the first craftsman known to have used serial numbers to identify his finished pieces—bringing science's tools into the nuts and bolts of efforts to systematize the material world.
This was revolution at the barricades: a headlong charge by its partisans to organize, abstract, and universalize their experience of daily life so that its distilled essence would be accessible to anyone who sought it out. Locke, who documented the details of his precision instruments and checked the amount of rainfall and the barometric pressure each day, noting the time of every measurement, was one more cadre in this growing revolutionary band, adding his tiny increment to the arsenal of knowledge.
In the eventful 1660s, Locke had to abandon his first weather diary within a few months. His political career and his own intellectual work consumed all his time and thought. But the experience stuck with him, and more than three decades later, when he retreated from public life for a time to Lady Masham's house in the Essex countryside, he resumed the habits of his youth. It took him some months to unpack his instruments and set up his weather observatory. At last, on December 9, 1691, he made his first observations. Four days later, his weather check had already become routine, a matter of a few minutes each morning. It had been two years since he had met the unquestioned leader of the new ways of understanding nature, and while Locke had certainly offered explicit homage to his new friend Newton, his resumed weather diary can be seen as a less obvious compliment to the ways of thinking Newton had championed.
Newton's reasons for returning Locke's sentiments were perhaps more simple. Anyone would take kindly to unstinting praise from an intelligent source—and Locke famously evoked affection. When he and Newton finally met, his warmth had its usual effect. Newton's letters to Locke show the impact of Locke's charm: "how extremely glad I was to hear from you," he writes in one; in another, he values Locke's judgment sufficiently to seek his reaction to what Newton called his "mystical fancies"; once he simply admits of "my desire to see you here where you shall be as welcome as I can make you."
In part, he relished the opportunity to tutor so well regarded a man. He gave Locke a private, annotated edition of the Principia and composed for him a simplified version of the proof that gravity makes the planets travel elliptical orbits. But Newton's intimacy with Locke seems to have extended well beyond such benevolent displays of mastery. From the beginning, Newton allowed himself to write openly about secret matters. Both men had subterranean interests—in alchemy, for one, the ancient study of processes of change in nature; and in questions of biblical interpretation and belief, which brought them to the edge of what the established English church would damn as heresy.
Locke responded with equal eagerness and candor. He always emphasized his deference on matters of natural philosophy to the man who wrote "his never enough to be admired book." But for the rest, he took part in what became an extended conversation with an intellectual companion, a partner in the pursuit of knowledge of the true nature of the Trinity, about the history of Scripture, about the transformation of substances. And along with his praise and their intense private exchanges, Locke had one thing more to offer: the use of his considerable influence with the Crown.
In the wake of the Glorious Revolution, Locke had become a supremely good man to know. King William cherished him, and he was known and connected by bonds of party and friendship to dozens of the newly ruling elite. He turned down most offers of patronage for himself, but he was perfectly placed to do kindnesses for those he valued.
Newton's service in the Convention Parliament ended on January 27, 1690. He returned to Trinity College and got back to what had once been a satisfactory round of daily life. He worked on corrections to a possible second edition of the Principia. He continued to examine the implications of the laws of motion, and he returned to studies of optics and light that had lain fallow for more than a decade. He began to think deeply about the theological consequences of his science, trying to define what kind of God could occupy the universe implied by the Principia. It seemed as if he was as much in his natural habitat as ever, wandering through his rooms and his garden, stopping suddenly, when a thought came, to "run up the stairs, like another Archimedes." To outward appearances, this was the man Trinity had sent to London, one who "aim'd at something beyond the Reach of humane Art & Industry."
But the Newton who returned to Cambridge in 1690 was not the same as the one who had set out for the House of Commons the year before. He was not bored, given his impressive productivity over the next few years. But he was restless, unsettled. Cambridge had become small. Its company was dull, uncomprehending of the man in their midst. Notoriously, an anonymous student who passed him on the street said, "There goes the man that writt a book that neither he nor any body else understands." In the face of such indifference (not even disdain!), London's attractions now included company that recognized Newton's worth at something like the value he had come to place on himself. Within months of his return to Cambridge, he let his new friends know he was ready for an escape. There was just one problem: in Cambridge Newton had no material wants. In London he would need to make a living—a good one. How?
Locke knew what to do. Beginning in 1690, he canvassed his most powerful acquaintances to advance his friend's cause. Newton knew what Locke was attempting. In October 1690 he wrote to thank Locke for his efforts; in November he betrayed a hint of urgency, even desperation: "Pray present my most humble service & thanks to my Lord and Lady Monmoth for their so kind remembrance of me. For their favour is such that I can never sufficiently acknowledge it." Such courtesy did not help matters this time—whatever Locke discussed with Monmouth never materialized. But the campaign was under way, with Newton's blessing and ever more urgent hopes.
And so Newton, by candlelight on that cold gray day in December 1691, pushed to one side his angry draft. He took another sheet to try again. "I thank you," he wrote, "for putting me in mind of Charterhouse." He dismissed the idea, but gently this time: "I see nothing in it worth making a bustle for." He summoned the deference due a man in a position to do him good. He begged John Locke to accept "my most humble service & hearty thanks ... for so frankly offering ye assistance of your friends if there should be occasion."
Days later, when Locke hurried back inside after recording his observations on the weather, careful not to risk his weak lungs and generally frail health on a raw December morning any longer than necessary, it was not Newton's wrath that greeted him. Instead, he read contrite thanks for help given and help to come. Locke took no insult from the rejection of his first attempt, and the letters to and fro confirm that while Newton would remain in Cambridge for five more years, his imagination had already carried him down the road to London. The rest was mere logistics for friends to arrange, to permit the incomparable Mr. Newton to take his rightful place in the big city.