Plato's Phaedo protrays the actual death of Socrates. It is a conversation Socrates has with his followers. At the beginning of the dialogue, Socrates drinks the poison hemlock. During the course of the dialogue he is dying, and the dialogue ends with his death.
He argues that death is not to be feared for several reasons. First, it may simply be nothingness, which, like sleep, is pleasant, or it may be the return of the soul to the divine, which is positive (he speaks of perhaps meeting Homer and the heroes in an afterlife).
More importantly, he argues that all philosophy aims at death, because death represents a separation of the soul from the body. The body, for Plato, is a obstacle to knowledge of the Forms and the divine, because it traps us in the phenomenal world. A philosopher trains the soul to be independent of corporeality by exercising the power of reason, so that the soul's understanding is not obscured by the changing material phenomena and it can perceive underlying eternal essences.