I have spoken with Newton about the possibility of a vacuum and about colors. * Sir Isaac Newton, 1642-1727, renowned English mathematician and natural philosopher, the most eminent physicist of his day. Among his principal achievements were formulation of the law of gravitation and laws of motion, invention of infinitesimal calculus, and the first correct analysis of white light. In his Opticks (1704) he postulated a combination of the wave and corpuscular theories of light similar to the present view. Newton found the existence of God reflected in the admirable order of the universe, but opposed the pantheistic notion of a world soul. He also denied the doctrine of the Trinity on the ground that such a belief was inaccessible to reason.