Isaac Newton, a British physicist and mathematician, is regarded as one of the greatest scientists in history. Before the age of 30 he formulated the basic concepts and laws of motion, discovered the universal law of gravitation, and invented the calculus. Newton was able to explain the motions of the planets, the ebb and flow of the tides, and many special features of the motion of the Moon and the Earth. He also made many important discoveries in optics, showing, for example, that white light is composed of a spectrum of colors. His contributions to physical theories dominated scientific thought for two centuries and remain important today.
Newton was born prematurely on Christmas Day in 1642, shortly after his father's death. When he was three, his mother remarried and he was left in his grandmother's care. Because he was small in stature as a child, he was bullied by other children and took refuge in such solitary activities as the building of water clocks, kites carrying fiery lanterns, sundials, and model windmills powered by mice. His mother withdrew him from school at the age of 12 with the intention of turning him into a farmer. Fortunately for later generations, his uncle recognized his scientific and mathematical abilities and helped send him to Trinity College in Cambridge.
In 1665, the year Newton completed his Bachelor of Arts degree, the university was closed because of the bubonic plague that was raging through England. Newton returned to the family farm at Woolsthorpe to study. During this especially creative period, he laid the foundations of his work in mathematics, optics, motion, celestial mechanics, and gravity.
Newton was a very private person who studied alone and labored day and night in his laboratory, conducting experiments, performing calculations, and immersing himself in theological studies. His greatest single work, Mathematical Principles of Natural Philosophy, was published in 1687. In his later years he spent much of his time quarreling with other eminent minds, including the mathematician Gottfried Leibnitz, who worked independently on the development of calculus; Christian Huygens, who developed the wave theory of light; and Robert Hooke, who supported Huygens' theory. These disputes, the strain of his studies, and his work in alchemy, which involved mercury (a poison), caused him in 1692 to suffer severe depression. He was elected president of the Royal Society in 1703, and he retained that office until his death in 1727.