Democritus

Democritus of Abdera took the atomism of Leucippus and made it a system: infinite atoms of every shape, differing in arrangement and position, colliding and entangling in the void to form innumerable worlds that come to be and pass away. Sensible qualities — sweet, bitter, colour — exist by convention; in truth there are atoms and void. The soul is made of the finest, roundest, most mobile atoms, a kind of fire, and perishes with the body; sight is the reception of thin films (eidōla) streaming off the surfaces of things. He wrote on everything — mathematics, music, agriculture, ethics — and his ethical maxims survive in quantity: cheerfulness (euthymiē) as the end of life, “a word is a deed’s shadow.” Later tradition made him the philosopher who laughed at human folly, and a traveller who studied with the magi of Persia and the priests of Egypt.

Plato never names him, though some said he wished to burn his books; Aristotle argued with him constantly and respectfully. Through Epicurus and Lucretius his physics became the atomism of the Garden and, much later, of modern science.