"...thou hast eyes, Yet see'st not in what misery thou art fallen," Tieresias tells him.
Oedipus is warned through-out the story that he ought to discontinue his search. Those who have spiritual eyes to understand and to see what he will find in the end know that it is a thing which is better left unseen. Yet he insists on seeking to shine the light of knowledge upon it and bring it to attention. It is interesting to note that after Oedipus has finally brought his crimes out into the open, and it is known to all what has transpired, Creon orders that the physical evidence of what has passed be removed from public sight out of respect for the sun, saying "revere The Sun whose light beholds and nurtures all. Leave not thus nakedly for all to gaze at A horror neither earth nor rain from heaven Nor light will suffer..." Even when horrid truth is made explicitly clear, those with wisdom prefer that it remain obscured. Oedipus' greatest foolishness consists in attempting to take that which ought to reside in the darkness of spiritual (which is to say unconscious and emotional) knowledge and forcing it out into the light of conscious day. From the moment he brings to light the truth, the remainder of the play is spent in trying to restore the truth to darkness.
In a futile attempt to send this truth back into the darkness from which it came, Oedipus blinds himself. He cries to his own eyes "No more shall ye behold such sights of woe...Henceforward quenched in darkness shall ye see Those ye should ne'er have seen." Oedipus seems to believe that if he blinds himself now, physically, he will somehow be able to restore his...
Yet in this moment, he makes the same mistake he has made through-out the play: he assumes that by affecting his physical vision he can somehow affect his spiritual knowledge. If anything, those who are blind more clearly "see" that which is spiritual, and no amount of physical blindness can erase a fact from the conscious mind once it has become implanted there. So, in the end, Oedipus fails once more to understand that nature of the world.
Yet to some degree Oedipus also shows his increasing wisdom in putting out his eyes. Those who had seen the truth with spiritual eyes before -- such as Tieresias -- were not driven mad by it. They were able to face that truth which resides in darkness with some equanamity, so long as they understood what should and should not be brought forward into the light of reason. perhaps by blinding himself, Oedipus is seeking to understand that part of human experience which can face the darkness unafraid. This idea is hinted at in his lines which says that without the sense, "Cut off from sight and hearing" one will be able to find inner peace, "...bliss to bide in regions sorrow cannot reach." Perhaps in the darkness, abiding with truths which cannot be brought safely to knowledge, Oedipus learns other secret things to comfort him -- that morality is transcended by love, for example, or that the worth of children is greater than the guilt of their birth. What is certain is that in the end, even bowed down by grief and guilt, Oedipus the blind seems far more able to face the truth -- even if he cannot "see" it -- than even before.
