Fragments

Democritus of Abdera, working with and building on the atomism of his predecessor Leucippus, argued that the universe consists ultimately of an infinite number of tiny, indivisible particles (atoms) moving through empty void, whose combinations in different shapes, sizes, and arrangements produce every observed object and quality, while properties like sweetness or color exist, in his famous formulation, only by convention rather than in the atoms themselves. Known through hundreds of fragments and later testimony, since none of his roughly seventy reported treatises survive complete, Democritus applied atomism across ethics, epistemology, and natural science, arguing that a cheerful, well-balanced state of mind, rather than pleasure or wealth, constitutes the highest human good. His atomism, developed partly as an answer to Eleatic arguments against void and plurality, was revived and transformed two centuries later by Epicurus into an ethical and physical system of enormous later influence.