- The Republic is divided between the search after justice and the construction of the ideal state; * the Parmenides between the criticism of the Platonic ideas and of the Eleatic one or being; * the Gorgias between the art of speaking and the nature of the good; * the Sophist between the detection of the Sophist and the correlation of ideas. The Theaetetus, the Politicus, and the Philebus have also digressions which are but remotely connected
Thus the comparison of Plato's other writings, as well as the reason of the thing, lead us to the conclusion that we must not expect to find one idea pervading a whole work, but one, two, or more, as the invention of the writer may suggest, or his fancy wander. If each dialogue were confined to the development of a single idea, this would appear on the face of the dialogue, nor could any controversy be raised as to whether the Phaedrus treated of love or rhetoric. But the truth is that Plato subjects himself to no rule of this sort. Like every great artist he gives unity of form to the different and apparently distracting topics which he brings together. He works freely and is not to be supposed to have arranged every part of the dialogue before he begins to write. He fastens or weaves together the frame of his discourse loosely and imperfectly, and which is the warp and which is the woof cannot always be determined.
The subjects of the Phaedrus (exclusive of the short introductory passage about mythology which is suggested by the local tradition) are first the false or conventional art of rhetoric; secondly, love or the inspiration of beauty and knowledge, which is described as madness; thirdly, dialectic or the art of composition and division; fourthly, the true rhetoric, which is based upon dialectic, and is neither the art of persuasion nor knowledge of the truth alone, but the art of persuasion founded on