Diagram showing refraction of light at a prism, by Isaac Newton, 1721. Sir Isaac Newton (1642 -1726/7) was an English physicist and mathematician (described in his own day as a "natural philosopher") who is widely recognized as one of the most influential scientists of all time and as a key figure in the scientific revolution. Newton made seminal contributions to optics, and he shares credit with Gottfried Leibniz for the development of calculus.