Among Plato's later dialogues, the Parmenides is one of the most significant. Not only a document of profound philosophical importance in its own right, it also contributes to the understanding of Platonic dialogues that followed it, and it exhibits the foundations of the physics and ontology that Aristotle offered in his Physics and Metaphysics VII. In this book, R.E. Allen provides a superb translation of the Parmenides along with a structural analysis that procedes on the assumption that formal elements, logical and dramatic, are important to its interpretation and that the argument of the Parmenides is aporetic, a statement of metaphysical perplexities. Allen's original translation of and commentary on the Parmenides were published in 1983 to great acclaim and have now been revised by the author.