The line mentions <span>Teiresias, the prophet who knew what would happen, and the seeing itself. Even though he is blind, Teiresias sees into the future and the truth of things. Even though he isn't blind, Oedipus doesn't see what he is doing and who he is. His tragic blindness will turn into the actual blindness, in a self-punishing act.</span>
The line relates to the main themes of Oedipus King because it alludes to the inner blindness of Oedipus and the outer blindness of Teiresias.
Explanation:
Teiresias is a blind man, but he can see the tragic future of Oedipus (who was destined to marry his mother, with whom he had two sons and two daughters, and to kill his father). Oedipus, even seeing perfectly has an inner blindness, because even hearing the prophecy he can not do nothing but fulfill it. Oedipus has evidence that whatever is happening on his way is leading him to fulfill the prophecy, but he has pretended not to see this evidence.
