Isaac Newton was born in Woolsthorpe, Lincolnshire, a premature infant not expected to live. His father (of the same name) had died just three months before. His mother, Hannah Ayscough Newton, remarried when he was three, and left him with his grandmother until her second husband died, in 1653, when Newton was 11. He was educated at King's School, Grantham, and it was assumed he would continue in the farming tradition of his family, but finally his mother became convinced that he should be prepared for entry to university, and in 1661 he went up to Trinity College, Cambridge, as a poor scholar who would have to earn his keep by doing menial tasks for the Fellows.
Newton showed no particular promise in his early years at Cambridge, but Isaac Barrow, who held the Lucasian chair of mathematics, gave him much encouragement. Newton took his degree without distinction (in 1665), and would have prepared for his MA, but in 1664 the Great Plague broke out in London, and the university was closed down the following year.
At home during the plague years, he studied the nature of light and the construction of telescopes. By a variety of experiments upon sunlight refracted through a prism, he concluded that rays of light which differ in color differ also in refrangibility - a discovery which suggested that the indistinctness of the image formed by the object-glass of telescopes was due to the different-colored rays of light being brought to a focus at different distances. He concluded (rightly for an object-glass consisting of a single lens) that it was impossible to produce a distinct image, and was thus led to the construction of reflecting telescopes, perfected by William Herschel and the Earl of Rosse. At the same time, he was working out his ideas on planetary motion.
On his return to Cambridge (1667), Newton became a Fellow of Trinity College, and, in 1668, took his MA. In the following year, Isaac Barrow resigned his chair in favor of his young pupil. Newton's lecture series resulted in an essay which later formed Book 1 of Opticks.
A falling apple had posed in Newton's mind the question of whether the force exerted by the Earth in making the apple fall was the same force that made the Moon "fall" towards the Earth, and so pull it in to an elliptical orbit round the Earth. Calculations showed him that it did, but it was not until 1684, after an exchange of letters with Robert Hooke, that Newton was fully in command of the dynamic principles involved. In that same year, Edmund Halley visited Newton to try to work through some planetary questions. To his surprise, Newton told him that the force between Sun and planets, reulting in an elliptical orbit, operated according to an inverse square law and that he had proved it. He later sent a small treatise on the subject to Halley. Halley persuaded Newton to write a book and, after much antagonism between Newton and Hooke, who demanded credit for discovering the inverse-square law of attraction, the book appeared in 1687 under the title Philosophiae naturalis principia mathematica (The Mathematical Principles of Natural Philosophy).
This important work, which had remained unpublished for years, established Newton as the greatest of all physical scientists. Its impact was immense. Newton had rewritten the whole science of moving bodies. He completed what the late mediaeval physicists had begun and Gallileo had tried to bring to fruition; and his three "laws of motion" formed the basis of all further work.
Meanwhile, the part Newton took in defending the rights of the university against the illegal encroachments of James II procured his a seat in the Convention Parliament (1689-90). In 1696 he was appointed Warden of the Mint, at a time when the government had debased the coinage, and a strong, incorruptible man was needed to deal with courterfeiters. He became Master of the Mint form 1699, having shown himself to be a brilliant administrator. He again sat in parliament in 1701 for his university, and in 1704 published Opticks in English, which he had refused to do until Hooke, his old enemy, was dead.
Much of Newton's life was spent in conflict with other scientists, particularly Hooke, Leibnitz, and Flamsteed, and he sought revenge for slights real or imagined by deleting references to their help from his work. He always took criticsm very badly, responding furiously - an anxiety which has often been explained in terms of his abandonment as a child - and showed signs all through his life of a persecution mania. A breakdown in 1693 heralded the end of his scientific work. Knighted in 1705, his last years were spent under the care of his niece. He never married, but was at his happiest in the role of patron to younger scientists and, from 1703, as a tyrannical president of the Royal Society.