Sophocles, in Oedipus the King, develops the themes of light and dark, and sight and blindness, in terms of clarifying the tragic fate of the protagonist. There is, however, great irony in these themes, for Oedipus cannot see what he is supposed to see until it is too late. Yet his first words in the play refer to a sight he could not have at that point, with respect to the murder of his father and marriage to his mother: "I would be blind to misery not to pity my people. . . . I see---how could I fail to see what longings bring you here" (159; 162). Of course, he does not know, and cannot know, at this point, that his actions in the past have brought the gods' curse upon his city and his people. However, he certainly had allowed himself to be compared to the gods, so that he is primed for the hubris which will bring him down as he seeks out the answers to the mystery of the curse.
Oedipus is spiritually and morally blind, in the dark, and the gods' every move is designed to open his eyes and move him into the light. The ultimate self-blinding of Oedipus is, in effect, the mark of his enlightenment. He has come to "see" morally and spiritually, and to accept that blindness is proof that he has seen what he has done.
Early on Oedipus asks "Whose fate does Apollo bring to light?" (164), not seeing that it will be his own fate. In fact, not knowing what he is saying, he declares "I'll bring it all to light myself" (167). The Chorus calls for the sending of the accursed one to "the black Atlantic gulfs" and appeals to "Apollo, lord of the light" (170).
Of course, the essence of the play with respect to these themes of light and dark, sight and blindness, is the self-blinding of the protagonist when he discovers the truth of his past, and must face his own arrogance with respect to the gods. He blinds himself because he cannot bear to look upon others who would only reflect his guilt back to him: "What good were eyes to me? No...