His most important work was 11Epi cuo ew (De natura), of which considerable fragments are extant (chiefly in Simplicius); it is possible that he wrote also Against the Sophists and On the Nature of Man, to which the well-known fragment about the veins would belong; possibly these discussions were subdivisions of his great work.
He is known as the first of the Sophists, i.e.
The Sophists and the Sceptics, Plato and Aristotle, the Stoics and the Epicureans took up the question, and from the time of Locke and Kant it has been prominent in modern philosophy.
This seems to have been interpreted by its author and by the Sophists in general in a subjective sense, with the result that it became the motto of a sceptical and individualistic movement in contemporary philosophy and ethics.
A famous problem concerning the cube, namely, to construct a cube of twice the volume of a given cube, was attacked with great vigour by the Pythagoreans, Sophists and Platonists.