In light of its history of interpretation, an interpretive essay on the fifth book of Plato's Republic is advanced, on the premise that existing views of the relation of Book V to the rest of the dialogue are inadequate. The metaphor of the "three waves" indicates more than a mere formal unity to the argument of Book V, since the logic of the first two "waves" only becomes evident in light of their dependence upon the logic of the third "wave" (...) . The "three waves" constitute a single, unified argument, which discloses the dependence of justice, as defined in terms of the state and individual in Book IV, upon the idea of the good set forth in Book VI. (shrink)