Definition: Democritus of Abdera, one of the 2 founders of the atomist school of Greek natural philosophy was known as the laughing philosopher. Atomists believed that there were tiny indivisible particles that moved within the infinite void of space. Leucippus taught or was an associate of Democritus. Democritus is thought to have also known Anaxagoras.
The atomists were trying to explain how there could be change without accepting the difficult idea that something could come into existence out of nothing. The indivisible particles (atoms) of the atomists could be reformed into anything. Besides a theory of nature, Democritus was also responsible for an ethical theory, although it is difficult to tease out what he said and what others wrote, since none of his writing remains.
Democritus was born around 460 B.C.
Source: Berryman, Sylvia, "Democritus", The Stanford Encyclopedia of Philosophy (Fall 2004 Edition), Edward N. Zalta (ed.)
