Isaac Newton was born prematurely on Christmas Day, 1642, by the Julian calendar then in use in England, so small that his mother later said he could have fit inside a quart pot. His father, an illiterate yeoman farmer, had died three months before his birth. When Newton was three, his mother Hannah married a wealthy clergyman named Barnabas Smith and moved to her new husband's house, leaving the boy with his maternal grandmother. Newton never forgave her. He later compiled a list of his sins as a young man, and among them was a confession that he had threatened to burn his mother and stepfather's house down with them inside. At Cambridge, he read the entire curriculum, decided Aristotle was wrong about most of it, and began developing his own theories in private notebooks he showed to almost no one. Then came the plague years. The university closed in 1665, and Newton retreated to the family farm in Woolsthorpe for eighteen months. In that period of enforced isolation, working entirely alone, he invented the mathematical framework now called calculus, formulated the inverse-square law of gravitation, and used a prism to demonstrate that white light is composed of a spectrum of colors. He was twenty-three when the plague sent him home and twenty-five when he returned to Cambridge with the foundations of modern physics and mathematics in his notebooks. He was appointed Lucasian Professor of Mathematics at twenty-six. He spent decades feuding bitterly with Leibniz over who invented calculus and with Hooke over optics. He published the Principia Mathematica in 1687. He ran the Royal Mint. He died in 1727 at eighty-four, having never married.