Democritus (/dɪˈmɒkrɪtəs/; Greek: Δημόκριτος Dēmókritos, meaning "chosen of the people"; c. 460 – c. 370 BC) was an influential Ancient Greek pre-Socratic philosopher primarily remembered today for his formulation of an atomic theory of the universe.Democritus was born in Abdera, Thrace around 460 BC. His exact contributions are difficult to disentangle from those of his mentor Leucippus, as they are often mentioned together in texts.