Isaac Newton, English mathematician, astronomer and physicist, (c1900). Portraint of Newton, and scene showing the observation of a lunar eclipse at the start of the 18th century. Newton's (1643-1727) discoveries were prolific and exerted a huge influence on science and thought. His theories of gravity and his three laws of motion were outlined in his greatest work, Philosophiae Naturalis Principia Mathematica (1687) and he is credited with discovering differential calculus. He also formulated theories regarding optics and the nature of light that led to him building the first reflecting telescope. Knighted by Queen Anne in 1705. Trade card, one from a series on astronomers produced by Liebig extract of meat, (c1900).