9. The Atomism of Empedocles. -- EMPEDOCLES OF AGRIGENTUM (about 495-435) embodies in his physics the two leading ideas of atomism: (1) The elements of material nature exist eternally, exempt from all change. Differing from earlier philosophers, he regarded as the original material not any one of the four elements but all four together. Mutually irreducible, they decompose each into homogeneous parts which mingle together to form the various beings of the visible universe. What we call the production or formation of a substance is simply a new arrangement of the particles of the four elements (mixis); what we term the disappearance or dissolution of a substance is the separation of those same particles to form new alliances (diallaxis). (2) Where does the motion of the mass of matter come from? The answer given by Empedocles is an enigmatic one: love and hatred attract and repel the particles of matter.