Another theme of the text is that mortals cannot escape the gods' will. The oracle of Delphi, who delivers the prophecy that Oedipus would kill his father and marry his mother, is thought to be the mouthpiece of the god Apollo. When Oedipus hears this prophecy, he decides that, rather than go home to Corinth, he will stay away: this way, he could not possibly, even inadvertently, kill his father, Polybus, and marry his mother, Merope. He doesn't know, of course, that Polybus and Merope adopted him and that Corinth is not really his home. In his pride, Oedipus assumes that he can escape the prophecy by outsmarting the oracle (and, by implication, Apollo), and this is actually what enables the prophecy to come true. When he decides not to return to Corinth, he goes to Thebes, where his birth parents are from. On the way, he encounters his birth father, Laius, who he kills in anger, and he marries his birth mother, Jocasta, shortly after he arrives. Oedipus's pride drives him to think that he can outsmart the oracle, and so he tries to do so; it is this very fact that actually enables the prophecy to come to fruition. It is said that pride goes before the fall, and this theme applies to Oedipus as well.