  Three predecessors heavily influenced Plato's thoughts on metaphysics and epistemology, Heraclitus (c. 540 B.C.–480–70), Parmenides (c.515 B.C.–449–40), and Socrates (470 B.C.–399). Only fragments remain of the writings of Parmenides and Heraclitus, including some contained in the dialogues of Plato. Socrates wrote nothing. Plato's depiction of his teacher is our primary source of evidence for his philosophy. Parmenides argued that there is and could be only one thing, Being. One could not even think or say what is not. Moreover, since change implies that something comes to be what it was not—I change from not being tan to being tan, nothing can change. Reality is static. The appearance of change is just that, a deceptive appearance. Unfortunately, what little we have left of Parmenides does not allow us to decide whether he argued that there is just one item, Being, in his universe—strict numerical monism—or whether there is just one kind of thing, beings or things that are. Parmenides' account of Being seems to have contributed to Plato's doctrine of Forms.