Democritus (dĭmŏkˈrĭtəs) [key], c.460–c.370 B.C., Greek philosopher of Abdera; pupil of Leucippus. His theory of the nature of the physical world was the most radical and scientific attempted up to his time. He avoided the abstractions of his predecessors, Anaxagoras (mind) and Empedocles (harmony and discord), by employing consistent mechanistic postulates that required no supernatural intervention. He held that all things were composed of atoms; these he asserted to be tiny particles, imperceptible to the senses, composed of exactly the same matter but different in size, shape, and weight. They were underived, indivisible, and indestructible. Democritus postulated the constant motion of atoms and, on this basis, explained the creation of worlds. He held that the whirling motion caused by the falling of atoms resulted in aggregations—the heavier atoms forming the earth and the lighter ones the heavenly bodies. He taught that what the senses perceive as quality is merely the result of a specific quantitative distribution of atoms. Sense perception yields only confused knowledge, telling us merely how things affect us; thought alone can apprehend the nature of things. Democritus' ethics were moderately hedonistic, teaching that the true end of life is happiness achieved in inner tranquility.
See A. T. Cole, Democritus and the Sources of Greek Anthropology (1967).
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