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[di mok'ri tus] ancient proponent of the atomic theory

Democritus was born in Abdera, in eastern Greece, about 460 B.C. His early life was spent in travel, visiting the great cities and centers of learning in Egypt and the Middle East.


Democritus' greatest work was a theory which has become a cornerstone of modern science -- the atomic theory of matter. He suggested that all substance in the universe was made up of particles so minute that nothing smaller was possible. He regarded those particles (what we now know as atoms) as unchangeable and indestructible, and as the only content of the universe besides the very space in which they existed. He also argued that some atoms differed from each other physically and that these differences explained the variety of kinds of matter in the universe. He suggested, for example, that the atoms of rock and earth were rough and jagged so that they held firmly together to make tough stable materials. By contrast, atoms of water were rounded and smooth so that water always flowed and assumed the shape of its container rather than having a definite shape of its own. Democritus also explained that atoms could neither be destroyed nor created, but could be rearranged in different combinations.

A diagram of Democritus' theory that one kind of basic indivisible particle, the atom, makes up all things. The variety in the world results from differences in the shape, arrangement, and position of atoms. The diagram shows how he conceived the same element making up different kinds of substance.
diagram of Democritus' atomic theory

A pictorial representation of Democritus' theory that matter consists of mixtures of atoms. The white hand in the top left picture contains some black, as shown in the enlargement at top right. In the bottom left picture the black and white dots are mixed. In the bottom right picture all the black and white dots are grouped together, forming a hand.
pictorial representation of Democritus' atomic theory

A rationalist, Democritus rejected the view held by the empiricists that nature was controlled by the actions of gods, demons, and spirits. On the contrary, he held that there existed a number of fundamental natural laws governing the phenomena of the universe. He saw the creation itself as a blind chance, a combination of the effects of natural laws to form the arrangements of atoms we know as the universe.

Unfortunately for Democritus, he was publicly scorned and ridiculed by one of the greatest empiricists of his time, Socrates, who scathingly rejected his view of nature. It was not until centuries after his death (about 370 B.C.) that modern chemists and physicists confirmed the accuracy of Democritus' remarkable reasoning and intuition.

Anthony Feldman and Peter Ford Scientists and Inventors, The People Who Made Technology from Earliest Times to Present Day New York: Facts on File, 1979

The Internet Encyclopedia of Philosophy

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This page was last updated on February 19, 2017.