In mechanics, Newton also markedly enunciated the principles of conservation of momentum and angular momentum. In optics, he invented the reflecting telescope and developed a theory of colour based on the observation that a prism decomposes white light into a visible spectrum. Newton notably argued that light is composed of particles. He also formulated an empirical law of cooling, studied the speed of sound, and proposed a theory of the origin of stars. In mathematics, Newton shares the credit with Gottfried Leibniz for the development of calculus. He also demonstrated the generalized binomial theorem, developed the so-called "Newton's method" for approximating the zeroes of a function, and contributed to the study of power series.
French mathematician Joseph-Louis Lagrange often said that Newton was the greatest genius who ever lived, and once added that he was also "the most fortunate, for we cannot find more than once a system of the world to establish." English poet Alexander Pope was moved by Newton's accomplishments to write the famous epitaph:
“ Nature and nature's laws lay hid in night; God said "Let Newton be" and
all was light. ”