Democritus

Democritus, who lived from about 460 to about 370 BC, was a pre-Socratic Greek philosopher from Abdera on the coast of Thrace, remembered above all for his atomic theory of the universe. None of his own writing survives except through second-hand reports, many of them from Aristotle, who saw him as an important rival. He was a polymath who wrote nearly eighty treatises, and he was also a pioneer of mathematics and of geometry in particular. Archimedes reports in The Method of Mechanical Theorems that Democritus had already asserted that a cone is one third of a cylinder with the same base and height, and a pyramid one third of the prism of the same base, before Eudoxus of Cnidus gave the rigorous proof by the method of exhaustion. The list of his works preserved by Diogenes Laertius includes titles on angles, the contact of circles and spheres, geometry, numbers and irrational lines and solids.