What is the Greeks' view about destiny in light of Oedipus Rex by Sophocles?

The only reason the
oracle at Delphi can offera prophecy regarding his futurethat he will kill his father and marry
his motheris because his fate is already determined.  Throughout the play, it does not matter
what Oedipus does; it seems as though he is on a fast train toward the destiny he tries so hard
to avoid.  Even before the play begins, he had made the decision not to return to Corinth, where
he believes his mother and father live (so that he cannot possibly kill him and wed her).
 Instead, he decides to make his way to Thebes, not realizing that his biological parents, Laius
and , live there.  In other words, Oedipus's attempts to avoid his fate actually allows it to
come to be; this makes it seem as though his choices have no real impact becauseno matter what
actions he takesthey lead to the destiny that has already been laid out for him.