One of the major themes in this play is the inevitability of fate. Oedipus thought he had done everything he could to avoid fulfilling the terrible destiny predicted for him by a religious oracle when he was a baby: that he would end up killing his father and marrying his mother. Those around him sought to avoid this in the first instance by leaving him out to die, but he was taken in by a kindly shepherd and grew up never knowing his father and mother, King Laius and Queen Jocasta, so that when he came across them he was quite unable to recognise him (and vice versa) and ended up unwittingly killing his father and marrying his mother. When the truth of this is eventually brought to light, the horror is so great that Jocasta kills herself and he puts out his own eyes and is forced to become an exile in his old age.
However the play does not just focus on such grim events: it also shows how people can cope with even the most terrible events that befall them. Oedipus does survive, he is strong, and in the sequel to this play, Oedipus at Colonus, he actually goes on to regain a measure of power and authority, becoming, in his death, an oracle-like figure.