Leucippus was a Greek philosopher and originator, together with Democritus, of the theory of atomism which Epicurus later developed. Although no original writings of Leucippus or Democritus survive, fragments of their teachings have been transmitted by later scholars such as Diogenes Laertius of the 3rd century AD who, in his Lives of Famous Philosophers, notes:

Leucippus holds that the whole is infinite ... part of it is full and part void ... Hence arise innumerable worlds, and are resolved again into these elements.