This is an English translation of Plato presenting a new conception of the Theory of Forms. Socrates and others discuss the epistemological and metaphysical puzzles of the Parmenides, with aims to define the meaning of the Sophist. The glossary of key terms is a unique addition to Platonic literature by which concepts central to each dialogue are discussed and cross-referenced as to their occurrences throughout the work. In such a way students are encouraged to see beyond the words into concepts. Focus Philosophical Library translations are close to and are non-interpretative of the original text, with the notes and a glossary intending to provide the reader with some sense of the terms and the concepts as they were understood by Plato's immediate audience.