When Newton arrived at Trinity College, Cambridge, in 1661, the school was one of England's finest institutes of higher learning. His career as a student lasted until 1665, when he took his degree as a Bachelor of Arts. He was elected a Minor Fellow of the College shortly thereafter, then a Major Fellow and a Master of Arts. In 1669, he was chosen to replace Isaac Barrow--on Barrow's recommendation--as the Lucasian Chair of Mathematics, a position that he would hold for thirty-four years. It was a remarkably rapid rise, especially for someone who had arrived in Cambridge from rural obscurity. The contrast between his sudden prominence and his Lincolnshire upbringing seems to have caused Newton some insecurity: for the rest of his life, he would be easily buoyed up by praise from his social betters, and easily distressed by criticism of any kind; further, he would insistently call himself a "gentleman" and trace his lineage back to noble families.
However, even though Newton's self-declared nobility was not legitimate, he certainly deserved his title of professor. Newton's notebooks, preserved for posterity, show that even in his first years as an undergraduate, his later interests were already emerging--a love of mathematics, a keen interest in astronomy and chemistry (joined with an abiding fascination with the pseudosciences of astrology and alchemy), and a curiosity concerning the details of history, ancient and modern, and its relationship with Biblical prophecy. He entered the world of higher education in a time of ferment, at the peak of the Scientific Revolution. The great minds of the 16th and early 17th centuries had prepared the way for this revolution: Nicholas Copernicus, Tycho Brahe, Johannes Kepler, and Galileo Galilei had opened the doors of astronomy and physics, while William Harvey and Andreas Vesalius had begun the mapping of the human body. Now, in Newton's time, great contemporaries (and rivals) like Robert Hooke, Edmund Halley, the chemist Robert Boyle, and the Danish astronomer Christian Huygens were making their own contributions to the expansion of scientific knowledge. But the dominant thinker of the 1660s was a Frenchman, René Descartes, who had based his system of physics on a purely mechanistic philosophy. He argued that the solar system, far from being a vacuum, as many claimed it to be, was filled with infinitesimally small particles, whose swirling interaction created "vortices" that carried the planets around the sun. Indeed, the traffic of these particles could explain all motion in nature.
Newton rejected these suppositions entirely--or rather, he recognized that they were unverifiable, and chose to focus his energies upon what he could verify, using experiments and the iron laws of mathematics. Such simple and modest theories would explain less in the short term than Descartes's all- encompassing theories; but in the long run, they would overturn Descartes entirely. Following this experimental method and by "thinking... without ceasing," as he would later phrase it, Newton made the basic scientific discoveries upon which all his achievements rested--and did so in just one year, 1666. The actual publication of these would come only slowly, and span Newton's lifetime; however, it was in this year, at the age of twenty-four, that Newton's genius had reached its greatest heights. The suddenness of his achievements gives them a fantastical quality, and has led many commentators to draw a comparison between scientific creativity and artistic genius.
Indeed, 1666 was an astonishing year for England as a whole--Poet John Dryden called it an annus mirabulus, or miraculous year. Because "666" was the number of the Beast, or Satan, in the Biblical Apocalypse of St. John, a variety of sects anxiously awaited the end of the world and the Second Coming. Great tragedies and wonders seemed to mark the year as special: London survived a great fire and the English fleet fought and won a great victory over Holland. Meanwhile, a great plague had begun in 1665 and was still ravaging the cities and countryside. Newton, fearing for his health in crowded Cambridge, retreated to his mother's home in Woolsthorpe. There, he settled down and began to experiment, and to think. The fruits of this period of seclusion would have profound consequences for the science of optics, or the study of light. They would also play a part in creating the mathematic field known as calculus. And by paving the way for Newton's later work on gravity, the theories he now pondered would fundamentally alter, perhaps for all time, how mankind understood the basic workings of the physical world.