When Oedipus first encounters Tiresias, the blind prophet proceeds to tell Oedipus after much pressure that Oedipus is the one who has brought the great plague down upon Thebes and that he is the murderer he has sent the residents of the city to find and cast away. Although Tiresias is visually impaired, he can still see the truth of the contingency. However, Oedipus is blind to the truth and immediately begins accusing Tiresias of being involved in a conspiracy with Creon to overthrow him as king. Oedipus casts insults at Tiresias about his blindness saying "You have no strength, blind in your ears, your reason and your eyes." (374-375). Tiresias responds by saying that the insults Oedipus has hurled will before long come back upon him. He also tells Oedipus that what has brought him greatness is the very luck that will ruin him. Tiresias says "Blind who could see, a beggar who was rich, through foreign lands he'll go and point before him with a stick," (460) implying that although Oedipus can see now, the truth will eventually blind him and cause him to loose all he has.
Oedipus remains blind to the truth until he can deny it no longer. After hearing the testimony of the herdsman it is perfectly clear to Oedipus that he has fulfilled the prophecy by killing his father and marrying his mother, in turn bringing the great misfortune about the city of Thebes. Upon discovering this, along with discovering Jocasta's dead body, Oedipus blinds himself with the pins on her dress and shouts that his eyes "would no longer see the evils he had suffered or had done, see in the dark those he should not have seen." (1280-1282). With this he realises that it