  Viewed from the perspective of the theory of soul presented in the Phaedo, the Republic theory involves not so much a division of soul as an integration into soul of mental or psychological functions that had been assigned, somewhat problematically, to the body. In both dialogues, Socrates appeals to the same Odyssey passage (Od. 20.17-18 at Phaedo 94d, Od.  20.17 at Republic 4, 441b), in which Odysseus prevails over his own anger: in the Phaedo, to exemplify a conflict between soul and body; in the Republic, to exemplify a conflict between two parts or aspects of the soul, reason and spirit. What the Republic offers is a theory of soul which, among other things, allows attribution of (in principle) all mental or psychological functions to a single subject, the soul. The theory thus respects the unity of the mind, in a way that the Phaedo theory does not. Moreover, the Republic theory also offers an attractive and well-supported articulation of desire into different kinds, which has profound implications both for what it is to have one's soul (or mind) in optimal condition and for how it is that this condition is best brought about. (To see that Plato is acutely aware of these implications, one only needs to look at what the Republic has to say about virtue and education.)  However, it may be worth insisting once more that we should not disregard the fact that the conception of the soul that features in the Republic is broader than our concept of mind, in that it continues to be part of this conception that it is soul that accounts for the life of the relevant ensouled organism. But if it is soul that accounts for the life of, say, human organisms, there must be some sense in which the human soul accounts not only for mental functions like thought and desire, but also for other vital functions such as the activities and operations of the nutritive and reproductive systems. To the extent that it leaves unclear how exactly it is that the soul is related to a broad range of activities (etc.) that are crucially involved in the lives of ensouled organisms, Plato's theory of the soul, in the Republic and beyond, remains incompletely developed. It is, of course, not surprising that the Republic does not confront the question how it is that the soul is related to life-functions that, as Aristotle recognizes (Nicomachean Ethics 1.13, 1102b11-2), are irrelevant to the ethical and political concerns of the Republic. However, context and subject matter impose no such constraints on the ‘plausible myth’ of the Timaeus, and also that dialogue, in presenting a somewhat revised version of the Republic's account (Tim. 69c ff.), fails to address the question how the soul is related to non-mental vital functions.