Ancient Greeks cared deeply about the pursuit of knowledge. Although the truth was often a terrifying concept, they still saw it as a critical virtue. One of the main underlying themes in Oedipus the King is the struggle of sight vs. blindness. Oedipus' blindness is not just physical blindness, but intellectual blindness as well. Sophocles has broken blindness into two distinct components.
The first component, Oedipus's ability to 'see' (ignorance or lack thereof), is a physical characteristic. The second component is Oedipus's willingness to 'see', his ability to accept and understand his fate. Throughout the play, Sophocles demonstrates to us how these components. From the very beginning, Oedipus was "blind." Oedipus has perfect physical vision. However, he is blind and ignorant to the truth about himself and his past. He desperately seeks to know about the death of his father.
At this point, it is obvious what Oedipus's action must be, to overcome the blindness. All of his actions thereafter are to that end. Sophocles introduces a prophet, a seer, Teiresias, into the play. Teiresias is a wise, old man who has supernatural powers to interpret the past and predict the future.
Ironically, Teiresias is physically blind, but can "see" the truth about Oedipus. Oedipus has trouble imagining that his father life was taken at his hands. It signifies that Oedipus as a man is ignorant to the true appearance of things - this blind man can 'see' the truth about Oedipus, yet Oedipus, in all of his physical perfection, cannot. As the play draws to a close, it is shown how Oedipus learns the true nature of things. 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 the truth, 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 the new knowledge Oedipus has, he realizes that it was he, and not Tiresias who was truly blind all along. He does not want to see the misery that he has brought on his family and city. The idea of sight is critical in Oedipus the King. When Oedipus could see with his eyes, his mind was ignorantly blind to the truth.
Tiresias is physically blind; he sees the truth from the beginning. These incidences involving Oedipus and Tiresias show how the power of the mind can far exceed any physical ability.