 Leucippus is named by most sources as the originator of the theory that the universe consists of two different elements, which he called ‘the full’ or ‘solid,’ and ‘the empty’ or ‘void’. Both the void and the solid atoms within it are thought to be infinite, and between them to constitute the elements of everything. Because little is known of Leucippus' views and his specific contributions to atomist theory, a fuller discussion of the developed atomist doctrine is found in the entry for Democritus.