Plato's Republic is a central text in the Western philosophical tradition and also a specimen of its author's exceptional literary and dramatic skill. The first book introduces, and conspicuously fails to answer, the question: What is justice? It also introduces the sophist Thrasymachus, who is quite certain that he knows what justice is, namely that it is nothing other than what the dominant power in the state considers to be in its own interest. The contentious confrontation between Thrasymachus and Socrates sets the stage for Plato's controversial construction of an ideal state in which the true nature of justice will be revealed. The Commentary draws attention to the way Plato anticipates developments in later books, thus serving as an introduction to Republic as a whole. Particular attention is paid to Plato's language and style, so that students of Greek literature as well as philosophy are well served.