Plato's Dialogue of the Parmenides

The Parmenides is perhaps the single most important writing of Plato for western metaphysics. In it, we see a young Socrates being schooled by the old Parmenides when he visits Athens. It's not only Plato's most influential metaphysical discussion, it's also his most baffling. We shall encounter Parmenides again fairly soon, but this time in a fictional form.