Isaac Newton

Isaac Newton was born on 25 December 1642 by the old English calendar, at Woolsthorpe Manor in Lincolnshire, a small farmhouse that still stands ^[1]. His father, an illiterate yeoman farmer also named Isaac, had died three months earlier. When the boy was three, his mother Hannah remarried and moved to a neighboring village, leaving him in the care of his grandmother. Biographers have long traced his guarded, combative temperament to that abandonment ^[1][2].

He was an indifferent farmer and a compulsive builder of models: windmills, water clocks, kites carrying lanterns. A schoolmaster at Grantham and an uncle who had studied at Cambridge saw more in him than the family farm did, and in 1661 he entered Trinity College, Cambridge, as a subsizar, paying his way by serving wealthier students ^[1][3].

In 1665 plague closed the university, and Newton returned to Woolsthorpe for the better part of two years. What happened there has no parallel in the history of thought. Working alone, in his early twenties, he developed the mathematics he called fluxions, known today as calculus; he bought a prism at a fair and showed that white light is a mixture of colors rather than a pure substance modified by glass; and he began the train of reasoning that connected a falling apple in the orchard with the orbit of the Moon ^[1][2][4].

He published none of it. Newton hoarded his discoveries for decades, and the habit later fed the bitterest priority dispute in science, the quarrel with Gottfried Leibniz over the invention of calculus ^[2]. When he finally returned to Cambridge, his talent was impossible to miss. In 1669, at twenty-six, his mentor Isaac Barrow resigned the Lucasian Professorship of Mathematics so that Newton could hold it ^[1][3].

Newton's first fame came from an instrument. Frustrated by the color fringes that lenses produced, he built a reflecting telescope in 1668, grinding the mirror himself; it was six inches long and magnified nearly forty times ^[3]. The Royal Society asked to see it, elected him a fellow in 1672, and published his first paper, a report on his prism experiments ^[3][4].

The paper drew immediate attack from Robert Hooke, the Society's curator of experiments, and Newton reacted as he always would: with fury, then withdrawal. He threatened to abandon natural philosophy altogether and for years published almost nothing ^[2]. The work continued in private notebooks, including long secret researches into alchemy and biblical chronology that occupied more of his pen than physics ever did ^[1][2].

In August 1684 the astronomer Edmond Halley visited Cambridge with a question the coffee houses of London could not settle: what path would a planet follow under a force weakening with the square of distance? Newton answered at once, an ellipse, and said he had calculated it years before ^[1][4]. Halley pressed him to write it out. Eighteen months of obsessive labor followed, and in 1687 the Society published Philosophiae Naturalis Principia Mathematica, with Halley paying the printing costs from his own pocket ^[4].

The Principia stated the three laws of motion and the law of universal gravitation, and from them derived the tides, the orbits of comets, the shape of the Earth, and the motion of the Moon ^[4][5]. No book before or since has so enlarged what mathematics could claim to explain. Within a generation, Newton's system was the framework of European science, and it remained so until Einstein's relativity refined it more than two centuries later ^[5][6].

In 1693 Newton suffered a breakdown, writing wild accusing letters to friends; modern readers have blamed overwork, depression, and possibly mercury poisoning from his alchemical experiments ^[2]. He recovered, and in 1696 left Cambridge for London to run the Royal Mint, first as Warden and from 1699 as Master ^[1][6].

He treated the post as anything but a sinecure. Newton oversaw the Great Recoinage, personally pursued counterfeiters through London's taverns and prisons, and sent several to the gallows ^[2][6]. Elected President of the Royal Society in 1703, he ruled English science with an autocrat's hand for a quarter century. Queen Anne knighted him in 1705, the first scientist so honored for his work ^[1]. He published Opticks in 1704, summing up his experiments on light in plain English rather than Latin, and it became a model for experimental writing ^[3][5].

The private Newton confounds the marble statue. He never married, formed few close friendships, and could be vindictive to rivals; after Hooke died, Newton is often said to have let the Society's portrait of him disappear ^[2]. He wrote perhaps a million words on alchemy and even more on theology, concluding in secret that the doctrine of the Trinity was a corruption, a view that could have cost him his career had he voiced it ^[1][2].

Yet he could also be plainly humble about the scale of what he did not know. Near the end of his life he compared himself to a boy playing on the seashore, diverted by a smoother pebble or a prettier shell, "whilst the great ocean of truth lay all undiscovered before me" ^[1]. His remark that he had seen further "by standing on the shoulders of giants," written in a letter to Hooke of all people, has become shorthand for how science grows ^[6].

Newton died in London on 20 March 1727 by the old calendar, aged eighty-four, and was buried in Westminster Abbey with a pomp normally reserved for kings; Voltaire, who attended, marveled that England honored a mathematician like a beloved monarch ^[1][6]. The poet Alexander Pope supplied the epitaph of the age: "Nature and Nature's laws lay hid in night: God said, Let Newton be! and all was light."

The measure of his legacy is that most of it is now taught to children. The laws of motion, the theory of gravitation, the calculus, the analysis of light: each would alone secure a scientist's immortality ^[4][5]. Newtonian mechanics still guides spacecraft, and the SI unit of force carries his name. Surveys of scientists and historians routinely place Isaac Newton first or second among the most influential figures science has produced ^[5][6].