Democritus and Leucippus Propose Atomic Theory

Working in Abdera, Leucippus and his student Democritus proposed that all matter consists of indivisible particles — atomos — moving through an infinite void. Democritus elaborated the theory extensively, arguing that atoms differ in shape, size, and arrangement, and that all observable phenomena result from their mechanical interactions. No supernatural agency was required. Though rejected by Aristotle and largely dormant for centuries, the framework anticipated core principles of modern atomic theory and influenced Epicurus, Lucretius, and eventually 17th-century natural philosophers including Boyle and Newton.