The fact that the audience knows the dark secret that Oedipus unwittingly slew his true father and married his mother does nothing to destroy the suspense.
Oedipus’s search for the truth has all the tautness of a detective tale, and yet because audiences already know the truth they are aware of all the ironies in which Oedipus is enmeshed.
As piteous as he appears in the final scene with Creon, there is more public spirit and more strength in his fierce grief and his resolution of exile than in any other tragic hero in the history of the theater.
Oedipus unravels his life to its utmost limits of agony and finds there an unsurpassed grandeur of soul.
It is at this point, when he determines to complete the search for the truth, knowing that he killed Laius and knowing that the result of his investigation may be utterly damnable, that Oedipus’s true heroism starts to emerge.
His rashness at this point is no longer a liability but becomes part of his integrity.
Oracles and prophets in this play may show the will of the gods and indicate future events, but it is the individual who gives substance to the prophecies.
Sophocles achieves an amazing compression and force by limiting the dramatic action to the day on which Oedipus learns the true nature of his birth and his destiny.
He is angry and incredulous when the provoked Teiresias accuses him of the crime, so he jumps to the conclusion that Teiresias and Creon are conspirators against him.
As plausible as that explanation may be, Oedipus maintains it with irrational vehemence, not even bothering to investigate it before he decides to have Creon put to death.
In the first case they are merely pitiful, but in the second they are tragic and take on a greatness of soul that nothing can conquer.
A crucial point in the play is that Oedipus is entirely unaware that he killed his father and wedded his mother.