Atomism

Democritus and Leucippus propose that everything is reducible to atomon — uncuttable particles — and the void. The arrangement of atoms explains qualities; nothing else is real. Epicurus inherits and ethicizes it (no gods, no afterlife, so be unafraid). Lucretius makes it poetry. In 1803 John Dalton revives it for chemistry. Modern physics complicates the picture but kept the name.