Isaac Newton

• 1. Introduction

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  Sir Isaac Newton said his mother told him he was so small at birth that he could have fit inside a quart mug. He was born prematurely on Christmas Day, the 25th of December 1642, at Woolsthorpe Manor in Lincolnshire. His father, also named Isaac Newton, had died three months before. This fragile child grew into an English polymath who worked as a mathematician, physicist, astronomer, alchemist, theologian, author and inventor. He became a key figure in the Scientific Revolution and the Enlightenment that followed. What happens when one mind tries to govern the motion of planets, the colours inside light, the security of a nation's coins, and the secret meaning of scripture all at once? The answers run through a haunted boyhood, a bitter feud over who invented calculus, and a death so honoured that two dukes and three earls carried his pall.

• 2. Two Golden Years

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  In August 1665, soon after Newton earned his BA at Cambridge, the university temporarily closed as a precaution against the Great Plague. He retreated to his home in Woolsthorpe, and the two years that followed have been described as "the richest and most productive ever experienced by a scientist". In that stretch he developed theories on calculus, optics, and the law of gravitation. The physicist Louis Trenchard More wrote that "There are no other examples of achievement in the history of science to compare with that of Newton during those two golden years."

  Newton had been an undistinguished Cambridge student, yet he worked entirely on his own. The scholar Richard S. Westfall noted that "By every indication we have, Newton carried out his education in mathematics and his program of research entirely on his own." He was self-taught, and he kept his notes with unusual care. He has been called an "exceptionally organized" person who dog-eared the pages he saw as important, and whose indexes were arranged alphabetically by topic.

  William Stukeley wrote that Newton "was not only very expert with his mechanical tools, but he was equally so with his pen". As a boy his lodging-room wall at Grantham was covered in drawings of "birds, beasts, men, ships & mathematical schemes". He has been described as a "Janusian thinker", someone who could combine seemingly disparate fields to spark creative breakthroughs. That habit of mixing alchemy, mathematics and theology would shape almost everything he touched.

• 3. A Quarrel Over Calculus

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  By the 20th of May 1665, a surviving manuscript shows Newton had already developed his calculus, which he called fluxions, far enough to compute the tangent and curvature at any point of a continuous curve. His tract De analysi per aequationes numero terminorum infinitas was sent by Isaac Barrow to John Collins in June 1669, and Barrow described it as the work "of an extraordinary genius and proficiency in these things". Newton then sat on his methods for years, reluctant to publish because he feared controversy and criticism.

  The German polymath Gottfried Wilhelm Leibniz developed calculus independently, with a very different and more convenient notation. The historian A. Rupert Hall concluded that Newton "was master of the essential techniques of the calculus by the end of 1666, almost exactly nine years before Leibniz". Both men are now credited, yet the priority dispute turned poisonous. Newton was close to the Swiss mathematician Nicolas Fatio de Duillier, who began accusing Leibniz of plagiarism starting in 1699.

  The mathematician John Keill renewed the plagiarism charge in 1708 in the Royal Society journal. The quarrel broke out in full force in 1711, when the Royal Society proclaimed Newton the true discoverer and labelled Leibniz a fraud. It was later found that Newton himself wrote the study's concluding remarks on Leibniz. The bitter controversy marred both lives until Leibniz's death in 1716.

• 4. The Anatomy Of Light

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  In 1666, Newton noticed that a prism spread a circular beam of light into an oblong band of colour, refracting different colours by different angles. He concluded that colour is a property intrinsic to light, a point that had until then been a matter of debate. He named the band a spectrum, and showed that a lens and a second prism could recompose it back into white light. By separating a coloured beam and shining it on various objects, he proved that light keeps its colour whether reflected, scattered or transmitted. This became Newton's theory of colour.

  Because every refracting telescope suffered from the dispersion of light into colours, Newton built a telescope using mirrors instead of lenses. In late 1668 he produced this first functional reflecting telescope, about eight inches long, grinding his own mirrors from highly reflective speculum metal and judging their quality with Newton's rings. Through it he reported seeing the four Galilean moons of Jupiter and the crescent phase of Venus. In 1671 the Royal Society asked for a demonstration, and their interest pushed him to publish his notes, Of Colours.

  When Robert Hooke criticised some of his ideas, Newton was so offended that he withdrew from public debate. His work on light was finally collected in Opticks, published in 1704, where he argued that light is made of particles or corpuscles. In 1704 he also presented a burning mirror built from seven concave glass mirrors, each about a foot across. David Gregory reported that it caused metals to smoke, boiled gold, and vitrified slate.

• 5. Mathematical Principles

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  On the 5th of July 1687, the Philosophiae Naturalis Principia Mathematica was published with the encouragement and financial help of Edmond Halley. In it Newton stated three universal laws of motion and the law of universal gravitation, laying the foundation for classical mechanics. He had used the Latin word gravitas, meaning weight, for the effect that became known as gravity. His laws were not improved upon for more than 200 years, and many advances of the Industrial Revolution rested on them.

  Newton's interest in celestial mechanics had reawakened with a comet that appeared in the winter of 1680-1681, on which he corresponded with John Flamsteed. The work began as De motu corporum in gyrum, a tract on about nine sheets copied into the Royal Society's Register Book in December 1684. In it he coined the term centripetal force. He used his mathematics of gravity to derive Kepler's laws, account for the tides, the trajectories of comets, and the precession of the equinoxes.

  Newton's biographer David Brewster reported that the work cost him his health. During his study of the Moon's motion in 1692-93, he "was deprived of his appetite and sleep", and told the astronomer John Machin that "his head never ached but when he was studying the subject". Critics accused him of introducing "occult agencies" into science with his invisible force acting across vast distances. In the second edition of 1713 he answered them in a General Scholium with his famous phrase, "Hypotheses non fingo".

• 6. Heretic In Private

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  By 1672 Newton had begun recording his theological researches in notebooks he showed to no one, papers that only became available for public examination in 1972. Over half of what he wrote concerned theology and alchemy, and most has never been printed. His writings reveal that he sided with Arius, who rejected the conventional view of the Trinity. Worshipping Jesus Christ as God was, in Newton's eyes, idolatry, an act he believed to be the fundamental sin. The historian Stephen Snobelen labelled him a heretic.

  Despite his private heresy, Newton was respected as a theologian by his contemporaries. Thomas Tenison, then Archbishop of Canterbury, told him "You know more divinity than all of us put together". John Locke described him as a man of great knowledge of the Scriptures whose equals he knew few of. William Stukeley wrote that no man in England read the Bible more carefully, thumbing over his own copy "in an extraordinary degree".

  Newton refused to take holy orders in the Church of England, unlike most of the Cambridge faculty. At the last moment in 1675 he received a government dispensation that excused him and all future holders of the Lucasian chair from ordination. He placed the crucifixion of Jesus Christ at the 3rd of April, AD 33. He also warned against viewing the Universe as a mere machine, writing that "gravity may put the planets into motion, but without the Divine Power it could never put them into such a circulating motion, as they have about the sun".

• 7. Master Of The Mint

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  In 1696, during the reign of King William III, Newton moved to London to take up the post of Warden of the Mint, obtained through the patronage of Charles Montagu, 1st Earl of Halifax. He estimated that 20 per cent of the coins taken in during the Great Recoinage of 1696 were counterfeit. Counterfeiting was high treason, punishable by being hanged, drawn and quartered. To gather evidence, Newton disguised himself as a habitue of bars and taverns and made himself a justice of the peace in all the home counties.

  Newton conducted more than 100 cross-examinations of witnesses, informers and suspects between June 1698 and Christmas 1699. He successfully prosecuted 28 coiners, including the serial counterfeiter William Chaloner, who was hanged. He also improved the technology itself, reducing the standard deviation of the weight of guineas from 1.3 grams to 0.75 grams. He raised the weekly output of coin from 15,000 pounds to 100,000 pounds.

  Newton became Master of the Mint upon the death of Thomas Neale in 1699, a post he held for the last 30 years of his life. He saved the Treasury then 41,510 pounds, roughly 3 million in 2012 terms. He also held surprisingly modern views on economics, arguing that paper credit such as government debt was a wise solution to the limits of metal currency. He believed the value of both metal and paper money was set by public opinion and trust.

• 8. A State Funeral

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  In April 1705, Queen Anne knighted Newton during a royal visit to Trinity College, Cambridge. The honour was likely motivated by the parliamentary election in May 1705 rather than by his science or his service at the Mint. He was only the second scientist to be knighted, after Francis Bacon. He had served two brief terms as Member of Parliament for Cambridge University, and according to some accounts his only comments were to complain about a cold draught and ask that the window be closed.

  Newton was a secretive and disciplined man with a prodigious appetite for work, which he placed above his own health. He was sparing with food and drink and became a vegetarian later in life. Although it was claimed he was once engaged, he never married. His half-niece Catherine Barton served as his hostess at his house on Jermyn Street in London. His library held 1,752 identifiable books, more than a quarter of them on theology.

  Newton died in his sleep in London on the 20th of March 1727, aged 84. He was given a state funeral, the first in England for someone recognised primarily for intellectual achievement. Two dukes and three earls bore his pall, and his body lay in state in Westminster Abbey for eight days before burial in the nave. He was the first scientist buried there, and Voltaire may have been present. When his hair was later examined it was found to contain mercury, probably from his alchemy, which could explain his eccentricity in late life.