Leucippus (; Greek: Λεύκιππος, Leúkippos; fl. 5th century BCE) was a pre-Socratic Greek philosopher. He is traditionally credited as the first philosopher to develop a theory of atomism. This is a distinction he shares with his student, Democritus, and which of them developed atomism is the subject of debate. Some philosophers argue that there was no historical Leucippus and that atomism was invented entirely by Democritus. Two books are attributed to Leucippus, but little else is known about his life or his teachings. Modern philosophy rarely attempts to distinguish the work of Leucippus and Democritus. Source: Wikipedia (en)