Democritus (c. 460 BCE - c. 370 BCE) was an ancient Greek philosopher from Abdera in Thrace who, developing the ideas of his teacher Leucippus, advanced the first systematic atomic theory of matter. [1] He held that everything is made of indivisible and unchanging particles moving in a void, and that the qualities of the world arise from their shapes, arrangements and motions. He also wrote on ethics, mathematics, cosmology and perception, though only fragments and later reports of his work survive. [2]
Life
Democritus was born at Abdera, a Greek colony on the coast of Thrace, around 460 BCE. Ancient sources report that he inherited wealth and spent it on extensive travel, possibly to Egypt, Persia and beyond, in pursuit of knowledge. He is said to have lived to a great age and to have written prolifically across nearly every field then recognised. [1]
None of his many books survives intact. His views are known through several hundred quoted fragments and through the summaries and criticisms of later writers, chiefly Aristotle, Theophrastus and Diogenes Laertius. Later tradition nicknamed him the laughing philosopher for his cheerful disposition, contrasting him with the weeping Heraclitus. [3]
Atomism
With Leucippus, of whom little is known, Democritus argued that the only things that truly exist are atoms and void. Atoms are indivisible, solid, unchanging and infinite in number, differing in size and shape; the void is the empty space in which they move and combine. [2]
Everything perceptible is a temporary arrangement of atoms: objects come into being when atoms cohere and perish when they disperse. Nothing is created from nothing, and nothing is destroyed. Change, which earlier philosophers such as Parmenides had argued to be impossible, is explained as rearrangement rather than generation. [1]
He drew a distinction that would later prove influential between properties that belong to atoms themselves and those, such as sweetness, bitterness and colour, that exist only by convention in the perceiver. This anticipated the later separation of primary and secondary qualities. [2]
Other work
Democritus also worked in mathematics, and is credited by later sources with establishing that the volume of a cone is one third that of a cylinder of the same base and height, and similarly for the pyramid and prism, results later proved rigorously by Eudoxus and Euclid. [3]
In cosmology he held that innumerable worlds form and dissolve throughout infinite space. His ethical fragments, the largest surviving body of his text, commend cheerfulness, moderation and inner tranquillity as the aim of life, a strand later developed by Epicurus. [1]
Legacy
Atomism was rejected by Plato and Aristotle and survived chiefly through Epicurus and, in Latin verse, through Lucretius's poem De rerum natura. Its revival in the seventeenth century by Gassendi, Boyle and others fed directly into the development of modern chemistry and physics. [2]
Although the atom of modern science is not the indivisible particle Democritus described, the name and the underlying insight that matter has a discrete structure trace back to him. [3]
