The irony of Oedipus's life in Sophocles Oedipus Rex is that he intends to find the truth and instead meets his fate. When a drunken man tells Oedipus he is not his father's son, Oedipus seeks the truth by traveling to consult a Dephic oracle; however, the oracle says merely that Oedipus would kill his father and beget children by his mother. Resolved to avert such a fate, Oedipus determines to never return to Corinth where he has grow up with Polybus and Morope, the king and queen. Unfortunately for Oedipus, along the way from Delphi, he becomes angered at a man who orders him off the road, killing him. Later, outside Thebes, Oedipus encounters the Sphinx and solves its riddle. As a reward, he is made King of Thebes and is given the hand of Jocasta in marriage. Thus, he has fulfilled the prophecy of the oracle, ironically, because he has made such efforts to prove him wrong.
Indeed, it is this pride, or hubris, which seals the fate of Oedipus the king. His burning demand to know the truth brings him to Delphi; his return from Delphi effects his encountering of the man in the chariot who--unbeknowst to Oedipus--is his father, and it is his insistent pride that causes Oedipus to demand the truth from Teiresias and Creon so that he can rid Thebes of its plague. Finally, with more irony, Oedipus seals his own fate as he calls for an investigation of Laius's death, an investigation that will not "bring what is dark to light," but, rather, bring about Oedipus's blinding, as in guilt and agony, Oedipus removes his own eyes.
As in Robert Frost's poem, "The Road Not Taken," Oedipus takes the path that seems the right one, but
knowing how way leads on to way,
he cannot turn back and not know what he knows now. His life is altered beyond anything he ever has imagined.