what is the dramatic purpose of the prologue in?

The opening of the play treats the murder of Laius as a detective story. Indeed, Oedipus speaks of tracks and traces, and the oracle gives little clue as to the events that will unfold. What Oedipus does as the tragic hero, however, is to speed up this revelation of events. Notable too is the literal plague that affects the city as well as the metaphorical ‘pollution’ within it: namely Oedipus himself. Indeed, in Athenian culture, the incest which Oedipus has committed - as well as the murder of his father - would have been considered both crimes against the natural order and crimes against the gods. Incest, of course, still carries a weighty taboo in most societies today. Because he fathered a child with his mother, he has engendered a plague on Oedipus' kingdom, Thebes, which has rendered the women sterile.

What is key to remember in analyzing this opening section of the play is the first glimpse Sophocles’ gives us of Oedipus’ deeper character. Sophocles starts the tragedy when Oedipus’ fortune is at its very height – he has solved the riddle and is a prosperous, respected king with wife and children. Note how many times in this early section of the play he is referred to as Oedipus the ‘great’. Some commentators have also found in Oedipus an unpleasant arrogance or pride – a sense of self-regard – which might be considered a ‘tragic flaw’ (an idea that seems to come from a mistranslation of the word hamartia meaning ‘mistake’). One might also suggest that Oedipus’ pride is manifest in his identification of himself with Thebes, the city - and of the way he takes up the challenge of finding the murderer in order to secure his own kingship.