On this day: 25 December 1642, Isaac Newton was born at Woolsthorpe Manor in Woolsthorpe-by-Colsterworth, a hamlet in the English county of Lincolnshire. Sir Isaac Newton was a physicist and mathematician who is widely regarded as one of the most influential scientists of all time. His book Philosophiæ Naturalis Principia Mathematica, first published in 1687, laid the foundations for most of classical mechanics. Newton also made contributions to optics and shares credit with Leibniz for inventing calculus.