“Nature and Nature’s laws lay hid in night; God said ‘Let Newton be!’ and all was light.” POPE. 164. Newton’s life may be conveniently divided into three portions. First came 22 years (1643-1665) of boyhood and undergraduate life; then followed his great productive period, of almost exactly the same length, culminating in the publication of the _Principia_ in 1687; while the rest of his life (1687-1727), which lasted nearly as long as the other two periods put together, was largely occupied with official work and studies of a non-scientific character, and was marked by no discoveries ranking with those made in his middle period, though some of his earlier work received important developments and several new results of decided interest were obtained. 165. Isaac Newton was born at Woolsthorpe, near Grantham, in Lincolnshire, on January 4th, 1643;[100] this was very nearly a year after the death of Galilei, and a few months after the beginning of our Civil Wars. His taste for study does not appear to have developed very early in life, but ultimately became so marked that, after some unsuccessful attempts to turn him into a farmer, he was entered at Trinity College, Cambridge, in 1661. Although probably at first rather more backward than most undergraduates, he made extremely rapid progress in mathematics and allied subjects, and evidently gave his teachers some trouble by the rapidity with which he absorbed what little they knew. He met with Euclid’s _Elements of Geometry_ for the first time while an undergraduate, but is reported to have soon abandoned it as being “a trifling book,” in favour of more advanced reading. In January 1665 graduated in the ordinary course as Bachelor of Arts. 166. The external events of Newton’s life during the next 22 years may be very briefly dismissed. He was elected a Fellow in 1667, became M.A. in due course in the following year, and was appointed Lucasian Professor of Mathematics, in succession to his friend Isaac Barrow, in 1669. Three years later he was elected a Fellow of the recently founded Royal Society. With the exception of some visits to his Lincolnshire home, he appears to have spent almost the whole period in quiet study at Cambridge, and the history of his life is almost exclusively the history of his successive discoveries. 167. His scientific work falls into three main groups, astronomy (including dynamics), optics, and pure mathematics. He also spent a good deal of time on experimental work in chemistry, as well as on heat and other branches of physics, and in the latter half of his life devoted much attention to questions of chronology and theology; in none of these subjects, however, did he produce results of much importance.