Leucippus c. 480 BC – c. 420 BC

Leucippus was an ancient Greek pre-Socratic philosopher and the founder, with his pupil Democritus, of the atomist tradition. Almost nothing survives of his biography or writings, and his very existence was doubted by Epicurus, but Aristotle and Theophrastus credit him with first formulating the view that the world consists of indivisible particles, atoms, moving in an empty void. His one preserved book title is The Great World System, and his single attested fragment articulates the principle that nothing happens at random but everything from reason and necessity. The fully developed atomism that descended from him through Democritus, Epicurus, and Lucretius shaped the early modern revival of corpuscular natural philosophy.