This 5th century BC philosopher introduced the idea of causality into philosophical thought. Although he may have come from Miletus, his homeland has also been placed in Elea in southern Italy or in Thrace, in Avdhira (Abdera).
He was a pupil of Zeno in Elea (this name meaning 'olive' in Greek, the Greeks have founded colonies in southern Italy in ancient times).
From Elea he travelled to Thrace where he settled and founded his school with Democritus, which was associated historically with the study of Atomistic Philosophy, which examined the structure and composition of matter.
Two works believed to have been his are 'The Great World System' and 'On the mind', the first an analysis of atomist theory of matter and the creation and structure of the world, the second consisting of his teachings on the senses and images perceived by them.
He wrote in the second work: 'Nothing is accidental, all things happen for some reason or necessity'. His philosophy was based on that of Parmenidhes, and included the concept of a set of opposites (which, like Heraklitos' concept of illusion resembled Hindu philosophy)-being and emptiness (or the void; non being). Being was considered capable of infinite smallness, equivalent to indivisibility, and hence called 'atomos' (hence the English word 'atom'), this long before the atom was split in the 20th century.