The Parmenides is, quite possibly, the most enigmatic of Plato's dialogues. The dialogue recounts an almost certainly fictitious conversation between a venerable Parmenides (the Eleatic Monist) and a youthful Socrates, followed by a dizzying array of interconnected arguments presented by Parmenides to a young and compliant interlocutor named "Aristotle" (not the philosopher, but rather a man who became one of the Thirty Tyrants after Athens' surrender to Sparta at the conclusion of the Peloponnesian War). Most commentators agree that Socrates articulates a version of the theory of forms defended by his much older namesake in the dialogues of Plato's middle period, that Parmenides mounts a number of potentially devastating challenges to this theory, and that these challenges are followed by a piece of intellectual "gymnastics" consisting of eight strings of arguments (Deductions) that are in some way designed to help us see how to protect the theory of forms against the challenges. Beyond this, there is precious little scholarly consensus. Commentators disagree about the proper way to reconstruct Parmenides' challenges, about the overall logical structure of the Deductions, about the main subject of the Deductions, about the function of the Deductions in relation to the challenges, and about the final philosophical moral of the dialogue as a whole. The Parmenides inspired the metaphysical and mystical theories of the later Neoplatonists (notably Plotinus and later, Proclus), who saw in the Deductions the key to the hierarchical ontological structure of the universe.