I thought that the moral was, that although humanity lives in a world where free will and pure knowledge don't exist because of the Gods, then our greatest ability (and mission) is to seek out knowledge and pure freedom.
And Oedipus is maybe the ideal of that.
But I don't know if that's what Sophocles intented.
Morals are difficult in epic stories like Oedipus. Themes are probably more helpful. Your definition is related to blindness and sight. Teiresias holds the key to the link between sight and blindness - for even though he is blind, he can still see and predict the future (if not the present). At the end of the play, moreover, Oedipus blinds himself, because what he has metaphorically seen (i.e. realized) leaves him unable to face his family or his parents in the afterlife). As with the previous theme, sight/blindness operate both literally and metaphorically within the play. Indeed, literal sight is juxtaposed with 'insight' or 'foresight'.
