Democritus was born around 460 BC at Abdera, a Greek city in Thrace on the northern Aegean coast. From a wealthy family, he spent his fortune travelling, tradition says, to Egypt, Persia and perhaps India. He wrote a great deal on physics, mathematics, music, ethics and medicine, but only fragments survive.
The laughing philosopher
The ancients called him the laughing philosopher because he found human worries and follies absurd, in contrast to Heraclitus, "the weeping philosopher". He was said to have lived over a hundred years.
Atoms and void
With his teacher Leucippus, Democritus developed atomic theory. Everything that exists is made of atoms, tiny, invisible, eternal and indivisible particles (Greek atomos means "uncuttable"), moving in the void. Atoms have no colour, taste or smell: they differ only in shape, size and position. Combining in different ways they form all things; when they separate, things dissolve. Nothing comes from nothing and nothing vanishes into nothing.
| Democritus's idea | Modern science |
|---|---|
| Matter is made of indivisible atoms | Matter is made of atoms, themselves made of smaller particles |
| Atoms move in the void | Particles are separated mostly by empty space |
| Qualities (colour, taste) depend on atoms' shape and arrangement | Chemical properties depend on the structure of atoms and molecules |
| Everything happens by necessity, without divine intervention | Nature follows physical laws |
Knowledge and ethics
Democritus distinguished the "bastard" knowledge of the senses from the "genuine" knowledge of reason: "by convention sweet, by convention bitter, in reality atoms and void". In ethics he sought euthymia, cheerfulness of mind, reached through moderation and calm.
Legacy
Plato never mentions him; Aristotle discusses him with respect. Atomism was taken up by Epicurus and the Latin poet Lucretius in De rerum natura, whose rediscovery in 1417 influenced the Renaissance. In the 19th century the chemist John Dalton revived the word "atom" for his theory of matter. At Abdera, near Xanthi, you can visit the ancient city's remains and a small museum.
See also Greek philosophy and Greek science.