English Mathematician
December 25, 1642 - March 20, 1727
Isaac Newton was a brilliant scientist and mathematician. He refined the laws of planetary motion, wrote the most influential book on physics and designed a reflecting telescope, yet suffered from debilitating insecurity and mental anguish. Plus, the most famous story told about him never actually happened.
Early Years

The hypothesis of matter's being at first evenly spread through the heavens is, in my opinion, inconsistent with the hypothesis of innate gravity without a supernatural power to reconcile them, and therefore, it infers a deity.

Isaac Newton

Isaac Newton was born on December 25, 1642, according to the Julien calendar in use at that time. The date becomes January 4, 1643, using the newer Gregorian calendar adopted by England in 1752.
He was baptized on New Year's Day, according to his family's calendar. He was born and raised in Woolsthorpe, Lincolnshire, England. His father, a prosperous farmer, died three months before he was born. Newton was tiny and weak as a baby, not expected to survive. When Newton was three years old, his widowed mother, Hannah Ayscough Newton, married a wealthy minister, Barnabas Smith. The newlyweds left Newton with his maternal grandmother. Although this was common practice at the time, Newton never overcame his sense of abandonment. At one point he even threatened to burn the Smiths' house down, with them inside.
Young Newton was enrolled at King's School in Grantham, a town in Lincolnshire. He had no interest in literature or poetry, but he was fascinated by mechanics and technology. He even invented an elaborate system of sundials, accurate to the minute. He lodged with a local apothecary and learned about chemistry.
When Newton was twelve, Barnabas Smith died. Mother and son were reunited, but the second marriage had resulted in three small children to feed. His mother pulled Newton out of school so he could run the family farm, but Newton was not suited for that responsibility. His uncle convinced his mother that Newton should leave the farm and enter Cambridge.
College Years
In 1661 Newton went to Cambridge. To pay his way he worked as a "sizar," waiting on tables and cleaning the wealthier students' rooms.
At the age of nineteen Newton wrote out a list of his sins, real or imagined, including his threat to burn down his mother's house. The list, written in code, featured the following items: "Making a mousetrap on Thy day"; "Setting my heart on money learning pleasure more than Thee"; "Punching my sister"; and "Wishing death and hoping it to some."
The university was still steeped in Aristotelian philosophy - a geocentric view - even though the scientific revolution was in full force, featuring the more modern heliocentric view of the known universe, in which planets orbit the sun. For his first three years at Cambridge, Newton was formally taught the traditional curriculum, but in his spare time he studied the modern philosophers. This dual course of study confused Newton and sabotaged his academic scores. He started to keep two sets of notes.
In 1665 Cambridge was forced to close, due to the threat of the Great Plague. Newton began an eighteen-month course of private study, during which he formulated a method of infinitesimal calculus, developed theories about light and color, and refined laws of planetary motion. Showing great dedication to his work, Newton stuck a blunt object into his eye as part of his research into light and color. It is possible that Newton saw an apple fall during this time, leading him to theories about gravity, but if so, the apple did not strike him in the head as is commonly believed.
Cambridge reopened in 1667. Newton returned and was elected a minor fellow at Trinity College. He was not considered to be a standout scholar.
In 1669 Newton earned his Master of Arts degree. He wrote a treatise about methods for dealing with an infinite series, expanding on ideas put forth in a book by Nicholas Mercator. When his friend and mentor, Isaac Barrow, resigned from his Lucasian professorship at Cambridge, Newton assumed the chair. He had to deliver an annual course of lectures as part of his duties, so he presented his work on optics and demonstrated a reflecting telescope he had designed and constructed. The Royal Society learned of Newton's telescope and asked him to demonstrate it in 1671.
Newton published his notes on light, optics, and color in 1672; the work would later be expanded into Newton's "Opticks: Or, A Treatise of the Reflections, Refractions, Inflections and Colours of Light." Robert Hooke and some other scientists disagreed with Newton's theories, theorizing that light is made of waves, not particles. Newton flew into a rage - the first of many that would punctuate and hinder his career. He considered leaving the Royal Society altogether, but some of his colleagues assured him that he was respected.
If Newton lacked self-control, he valued caution in matters of discovery. He wrote, "We are to admit no more causes of natural things than such as are both true and sufficient to explain their appearances."
Years of Isolation
Newton suffered a nervous breakdown in 1678, then, in the following year, his mother died. Newton withdrew from the academic community almost entirely for six years, answering correspondence with brief notes.
Meanwhile, Newton's rival, Robert Hooke, presented his theories about planetary motion. Society members Christopher Wren and Edmond Haley supported Hooke's theories but felt that a mathematical demonstration was needed. Halley discussed the problem with Newton, who was coming out of his self-imposed hiatus, and Newton was quick to answer that the orbits would take the form of an ellipse. Halley offered to pay Newton for fleshing out his computations so they could be published.
The Single Most Influential Book on Physics
Newton once wrote, "To explain all nature is too difficult a task for any one man or even for any one age. 'Tis much better to do a little with certainty and leave the rest for others that come after you." Nevertheless, Newton essentially explained all of the known universe with his mathematical equations.
Newton published his "Philosophiae Naturalis Principia Mathematica" or "Mathematical Principles of Natural Philosophy" in 1687. The work represented twenty years of thought and eighteen months of actual writing. Readers commonly refer to the book simply as "Principia." It contains essential concepts of physics in every area known at the time, other than energy. Newton described the nature of bodies in motion using three basic laws. These laws explain elliptical orbits, the pull of the sun's gravity, how the moon revolves around Earth, and more. His calculations explained the motion of the Earth's tides and defined the bulge at the Earth's equator.
Newton, the mathematical genius, once said, "I can calculate the motion of heavenly bodies, but not the madness of people."
An End of Scientific Pursuits
In 1689 Newton was elected to represent Cambridge in Parliament. In London, he met a broader group of intellectuals, including philosopher John Locke.
Newton suffered another nervous breakdown in 1693. He blamed lack of sleep, but other possibilities include lack of promotion by William III or Mary II, exhaustion from overwork, or mercury poisoning. During this time he wrote scathing letters to his friends and colleagues, accusing them of betrayal and conspiracy. He recovered and sent letters of apology, then withdrew from the scientific community. He apologized to John Locke and Samuel Pepys for wishing they were dead.
Personal Interests and Beliefs
Newton dabbled in alchemy, a pseudoscience that focuses on turning base metals into gold. These metals, including mercury, may have altered his mental state.
Although Newton was raised in an Anglican family with some Puritanical beliefs, he came to doubt the existence of the Holy Trinity. He conformed outwardly with the Church of England for the sake of his career, but he secretly thought that worshiping Christ is a form of idolatry and that the Devil does not exist. He refused the sacrament on his deathbed, but he was buried in Westminster Abbey in spite of his break with Church doctrine. Ultimately, however, Newton believed in God. He wrote, "In the absence of any other proof, the thumb alone would convince me of God's existence."
He was obsessed with eschatology, the study of the end of the world, and he postulated that the end of the world would come sometime after the year 2060.
He compiled a detailed analysis of the Bible, trying to decode hidden prophecies. He once commented, "There are more sure marks of authenticity in the Bible that in any profane history."
Master of the Mint and All-Powerful Head of the Royal Society
In 1696 Newton started a new career as Warden of the Mint. He moved to London to live with his niece, Catherine, and immediately worked to redesign the British monetary system. At the time many coins were forgeries, and sometimes the metal used to make the coins cost more than their face value. Newton recalled all old currency and issued improved versions. He kept careful records of counterfeiters and prosecuted them relentlessly.
He was promoted to Master of the Mint, a position he would retain until his death. He continued to reform currency and punish counterfeiters, plus he moved the British pound sterling from the silver to the gold standard.
When Newton's enemy, Robert Hooke, died in 1703, Newton was elected president of the Royal Society. He was an autocratic leader, controlling the lives and careers of younger scientists.
Gottfried Leibniz, a German mathematician, accused Newton of plagiarizing his research on infinitesimal calculus. Newton used his power with the Royal Society to influence the investigative committee - Newton, of course, won the case. Later historians agree that the two men probably arrived at their theories independently, with no plagiarism involved.
Final Days
Newton died on March 20, 1727, according to the Julien calendar, or March 31, 1727, using the newer Gregorian calendar. He was eighty-five. Hair samples revealed high levels of mercury, possibly the result of his experiments in alchemy, which may have contributed to his mental agitation and his death.
In his life Newton achieved wealth and fame, but he had few friends and he never married. He was chronically lonely. He may have suffered from bipolar disorder or autism.
He left behind an enormous body of work, with manuscripts containing about ten million words.
He once described his life and legacy this way: "I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."