According to St. Augustine, poetry is something that is to be used, but not enjoyed. This same view is evident in some of Plato's works, particularly the Republic, but it is undeniable that Plato himself uses poetic devices -- things like very deliberate characterisation and myth are employed to great effect in the Phaedo. In light of his having more or less proscribed the enjoyment of poetry, the irony is striking. But in order to be functional, poetry does not necessarily have to be unpleasant. Perhaps the opposite is the case, and to fulfil its purpose within the greater framework of a text a poetic device (or a series of them) has to be well-executed and enjoyable in and of itself, before it can be considered functional. Arguably, this is especially true in the Phaedo.
The dialogue itself is replete with poetic devices ingrained into its very structure. This is evident from the outset; the Phaedo is presented as a sort of meta-dialogue, Phaidon's first-hand account of Socrates' last hours (and his last conversation with his friends) as related to the neo-Pythagorean Echecrates. Doing this is a very subtle and sly way for Plato to engage his reader's interest. As Echecrates is eager to learn about Socrates' death and the discussion that preceded it, so too does the reader become drawn in -- he or she takes up the position of an interested outsider unconsciously, alongside the neo-Pythagorean.
A consequence of presenting philosophy in this way, as a conversation rather than as a monologue, is that it allows for characters with distinct thought patterns and interlocutory tendencies to emerge. The interlocutors and other participants in the conversation were actual people in Athens; anyone of the time reading the dialogue would likely know who they were. Perhaps this is less a poetic concern than a purely pragmatic one. By incorporating real characters instead of fictitious ones, Plato appeals to his audience's existing knowledge of Athenian society and acquaintance with the people Socrates is speaking with to make the dialogue more realistic and dynamic.
The fact that this is Socrates' death that we as outsiders are witnessing makes this characterisation almost painfully poignant -- his wife Xanthippe being led away and taken home in tears after their final goodbye at the beginning of the dialogue, for instance, makes it clear that this is going to be no ordinary outpouring of philosophical thought. It is difficult to imagine how heartrending it would be to sit at the side of a dear friend condemned to be executed and attempt to carry on a relatively normal conversation according to his wishes; this too functions as a device for engaging the reader further, as we too are curious about how the discussion will proceed. It speaks volumes about the character of both Phaidon and Socrates that the fondest wish of the former is "to remember Socrates, and what he said himself, and what was said to him" -- it brings emotions into play, as we come to understand exactly how precious Socrates was to his friends (Plato, 461). And by allowing emotion to enter into the equation, the argument that follows becomes deeply personal.
Before it begins, however, poetry itself is mentioned directly: Socrates has been composing it in his spare time, a new pursuit for him, and achieving middling success. But instead of becoming a "fiction-monger" and creating something entirely new, he takes up the style of Aesop and composes a fable (464). This is a subtle reiteration of the argument against poetry for enjoyment's sake that appears in the Republic. A fable is not primarily a thing to be enjoyed, but a story with a moral from which something important can be learnt. It is primarily functional, and any poetry that happens to be involved is incidental to the cause -- but not unnecessary, as if a fable is not somehow enjoyable to read or hear, it is unlikely that anyone will pay attention to it for long enough to discern its meaning. The tone thus set, Socrates proceeds directly to the argument that makes up the bulk of the Phaedo.
The subject matter of the argument -- that is, the soul's immortality, and how it can be demonstrated -- becomes even more profound after the poetic exposition at the beginning of the dialogue. The scene has been set, with Socrates waiting for his executioner to bring him the hemlock which he has been condemned to drink, surrounded by his friends; and the topic he wants to discuss is what comes after death. This, too, appeals strongly to the reader's emotions; envisioning Socrates' friends listening to his theories about death and what happens afterward as Socrates himself is about to die is heartwrenching to say the least.
The argument is divided into four distinct parts, each of which demonstrate that the soul by its very nature must be immortal. Therefore it must continue to exist even after the body has perished. But before the argument can begin, the hypothesis on which it rests must be introduced: that there are souls that inhabit the underworld, and they come 'back to earth' to inhabit the bodies of living men. The entire argument is devoted to demonstrating this key point.
First is the idea that all things proceed from their opposites, and are defined by them: for instance, something weak cannot become weak unless it has at some point been stronger, and vice versa. Similarly, something cannot be 'dead' unless it has at some point been alive -- like weakness proceeding after strength, death follows after life. And since the opposite also applies, there must be some process by which the dead can return to be living again. Since it seems impossible for fleshly things that are susceptible to rotting away to return to their original state, there must be something else that 'dies' and is 'reborn' -- this is the soul.
Following after the argument from opposites, Socrates says that everything we can know is not learned from nowhere; rather 'learning' as such is a process of recollection, of remembering things that we already knew but had forgotten. The part that forgets is the soul, and the moment of forgetting is its birth into a mortal body; it spends the rest of its mortal life recalling things. This, too, demonstrates the soul's immortality, because in order to have forgotten it must have existed before its birth. Next, Socrates proposes that the soul is indivisible, in contrast to the mortal body, which perishes and rots away. It is because of this that it is likely that the soul is immortal; for the divine, too, cannot be broken into pieces, and it is indissoluble. A soul that is pure -- uncorrupted by meanness and vices of the flesh -- tends to cling only to itself; and by so doing it partakes in the immortality of the divine, since it contains nothing that is prone to rotting away. And finally, Socrates posits that the soul partakes in the form of Life; and as in Platonic terms all things are defined by the form in which they participate, it is inconceivable to think of the soul as ever being anything but fully alive, even after the mortal body to which it was attached has passed away.
Unlike the dialogue's exposition, the argument itself is not deeply personal and rife with pathos -- it is closer to being purely theoretical than any other part of the dialogue. Like Aesop's fables, it is functional, but although it is beautifully-written it needs to be finished off in such a way that it becomes accessible to the reader. Even if we have followed the argument carefully from start to finish and understood each proposition, in order to ensure full comprehension of it there must be a way to check whether we actually understood the whole of what went on. This is where poetic devices once again become necessary: Socrates concludes his argument with a myth describing what happens to souls after death. Bolstered by the mythical example, the argument is no longer strictly theoretical -- it becomes personalised again, relevant and applicable to the reader (as well as to Cebes and Simmias, the interlocutors).
The myth is undeniably poetry. But it is not present in the dialogue for its own sake -- it is necessary that the entire argument has been read through and understood before the myth can begin to make sense. Without comprehending the argument, it is an attractive story; something that a 'fiction-monger' might produce, something that we can enjoy reading without really knowing why. But its primary function is to cement the argument in the reader's consciousness. The myth brings the reader back to 'the real world', as it were, but it is a world that is fundamentally different from the way that it was before we understood the argument; with the argument's tenets placed within a poetic framework, they are more readily understood.
In the Phaedo, then, it is evident that poetry is a tool used to fulfill specific purposes -- first to draw the reader into the argument, and second to allow him to see for himself how the argument changes his world. That it is enjoyable is less important than that it succeeds in elucidating and clarifying the argument; but that it is enjoyable is also necessary, since if it were not accessible it would be inadequate to achieving its purpose.
Great Dialogues of Plato, trans. W.H.D. Rouse. New York: Penguin Putnam Inc., 1999.