What quotes show Oeidpus's downfall?

The following quotations map out the trajectory of Oedipus's eventual downfall. The first one we're going to look at is an example of what's called dramatic irony. This is where we know something that a character doesn't. Here, Oedipus is addressing the good folk of Thebes:

I thought it wrong, my children, to hear the truth from others, messengers. Here I am myself—you all know me, the world knows my fame: I am Oedipus.

"You all know me." Well, the people of Thebes don't actually know him at all; they think they do, but they don't. But then, not even Oedipus knows who he really is, either. And as is customary in Greek drama, the terrible truth is eventually revealed to Oedipus indirectly, through messengers. Ironic indeed.

I curse myself as well…if by any chance he proves to be an intimate of our house.

Oedipus pronounces a terrible curse on the killer of Laius. Of course, at this stage in the play, he doesn't know that he is the killer. The curse upon the killer and himself—actually one and the same person—foreshadows the terrible revelation that will take place later on.

This day will bring your birth and your destruction...

As we see with the Sphinx, Oedipus likes solving riddles. However, this isn't one of them. He claims to want to get at the truth of what happened to Laius and yet he ignores the prophecy of the blind seer Tiresias. The prophet is alluding to the fact that Oedipus's eventual downfall began on the very day of his birth when he was exposed on the mountains to die.

Pride breeds the tyrant violent pride, gorging, crammed to bursting with all that is overripe and rich with ruin—clawing up to the heights, headlong pride crashes down the abyss—sheer doom!

The Chorus warns Oedipus of the dangers of hubris, or overweening pride. Despite Jocasta's desperate pleading, Oedipus is determined to get at the truth, whatever it takes. Pride is the ultimate cause of Oedipus's downfall and the Chorus's warning indicates just how serious a matter this is.

I count myself the son of Chance, the great goddess, giver of all good things—I'll never see myself disgraced.

Oedipus is only half right here. Yes, he has indeed been the beneficiary of good fortune in life. After all, he was extremely lucky to have survived being exposed on the mountainside when still a tiny new-born baby. But fortune can play cruel tricks, and Oedipus will come to realise too late that out of the good luck of survival came eventually the death of Laius, and out of that his own downfall.

What good were eyes to me? Nothing I could see could bring me joy.

The terrible truth has finally been revealed and Oedipus, in his overwhelming anguish, has gouged out his own eyes. His downfall is complete. Yet some remnant of pride still remains. Oedipus can't bring himself to face those around him, to look into their eyes and see their pity.