Democritus c.460-c.370BC
Greek philosopher

Born in Abdera, Thrace, he was one of the most prolific of ancient authors, publishing many works on ethics, physics, mathematics, cosmology and music, but only fragments of his writings (on ethics) survive. He is best known for his physical speculations, and in particular for the atom theory he developed from Leucippus, whereby the world consists of an infinite number of everlasting atoms whose different characteristics and random combinations account for the different properties and qualities of everything in the world. Supposedly known as 'the laughing philosopher' in the ancient world because of his wry amusement at human foibles, he was an important influence on Epicurus and Lucretius, and he was the subject of Karl Marx's PhD thesis, 'The Atomic Theories of Democritus and Epicurus'.

Bibliography: David J Furley, The Greek Cosmologists (1987)