Parmenides a Greek philosopher of the fifth century B.C. Parmenides tried to prove by logic that change does not exist. He believed that only a universal, eternal, and unchangeable Being is ultimately real and that the many objects that seem to exist are only illusions. This philosophy was opposed to that of Heraclitus, who believed that change is the fundamental principle of the universe. Parmenides was a native of Elea, a town in southern Italy. His ideas influenced the philosophy of Plato.