As a young man in Corinth, Oedipus hears a rumour that he is not the biological son of Polybus and his wife Merope. When Oedipus sounds them out on this, they deny it, but, still suspicious, he asks the Delphic Oracle whom his parents really are. The Oracle seems to ignore this question, telling him instead that he is destined to "Mate with [his] own mother, and shed/With [his] own hands the blood of [his] own sire." Desperate to avoid his foretold fate, Oedipus leaves Corinth in the belief that Polybus and Merope are indeed his true parents and that, once away from them, he will never harm them.
On the road to Thebes, he meets Laius, his true father. Unaware of each other's identities, they quarrel over whose chariot has right-of-way. Oedipus's pride leads him to murder Laius, fulfilling part of the oracle's prophecy. Shortly after, he solves the riddle of the Sphinx, which has baffled many a diviner: "What is the creature that walks on four legs in the morning, two legs at noon, and three in the evening?"
To this Oedipus replies, "Man" (who crawls on all fours as a baby, walks upright later, and needs a walking stick in old age), and the distraught Sphinx throws herself off the cliffside. Oedipus's reward for freeing the kingdom of Thebes from her curse is the kingship and the hand of queen Jocasta, his biological mother. The prophecy is thus fulfilled, although none of the main role players know it.
The play begins years after Oedipus has taken the throne of Thebes. The Theban chorus cries out to him for salvation from the plague sent by the gods in response to Laius's murder. Oedipus searches for the murderer, unaware that he himself is the murderer.
The blind prophet Tiresias is called upon to aid the search, but, after his warning against following through with it, Oedipus oppugnes him as the murderer, even though he is blind and aged. In response, an angry Tiresias tells Oedipus that he is looking for himself, causing the king to become enraged in incredulity. He then accuses the prophet of conspiring with Creon, Jocasta's brother, to overthrow him.
Oedipus calls for one of Laius's former servants, the only surviving witness of the murder, who fled the city when Oedipus became king in order to avoid being the one to reveal the truth. Soon a messenger from Corinth arrives to inform the king of the death of Polybus, whom Oedipus still believes to be his real father. At this point, the messenger informs him that he was in fact adopted and that his true parentage is unknown. In the subsequent discussions between Oedipus, Jocasta, the servant and the messenger, the second-mentioned surmises the truth and runs away in shame.
Oedipus remains stubborn and incredulous until a second messenger arrives with the shepherd, who reveals that Oedipus himself was the child abandoned by Laius. He realises what he is, and leaves in a rage. An attendant then breaks the news that Jocasta has hanged herself. On discovering her body, Oedipus gouges out his eyes with the golden brooches on her dress.
The play ends with Oedipus entrusting his children to Creon and declaring his intent to live in exile. Although he initially begs for the company of his children, Creon refuses, and Oedipus is exiled alone. The theme can perhaps be summarized with a line spoken by Tiresias: "Wisdom is a dreadful thing when it bringeth no profit unto its possessor" (Sophocles). In the denouement, the chorus narrates his tragic history.
In 467 BC, Sophocles's fellow tragedian Aeschylus won first prize at the City Dionysia with a trilogy about the House of Laius, comprising Laius, Oedipus and (the sole surviving play) Seven against Thebes. Aeschylus presumably treated Oedipus's story as one link in a chain of calamities that befell Laius, his son and his grandsons.
Sophocles did not share Aeschylus's predilection for writing connected trilogies. His play, then, by necessity, treats the Oedipus myth with a much narrower focus than its epic and tragic predecessors. Though Laius's story obviously plays a part in the tragedy, the travails of Oedipus become much more self-contained. No longer part of an entire House's inexorable slide to ruin, Sophocles's Oedipus the King is instead the tragedy of a single man who tries to outwit the defiant Delphic Oracle and fails.
There was an oracle once that came to Laius—
I will not say that it was Phoebus's own,
but it is was from His servants—and it told him
that it was fate that he should die a victim
at the hands of his own son, a son to be born
of Laius and me.
The oracle is implicitly conditional: if Laius has a son, that son will kill him, so Laius is in no way a victim of fate. He knowingly fathers a child and suffers the predicted consequences. Hearing this prophecy prompts Oedipus to recall one that he received from the Delphic Oracle shortly before he left Corinth (787-93):
And so I went in secret off to Delphi.
Apollo sent me back without an answer,
so I didn't learn what I had come to find.
But when he spoke he uttered monstrous things, strange terrors and horrific miseries—
it was my fate to defile my mother's bed,
to bring forth to men a human family that people could not bear to look upon,
to murder the father who engendered me.
Given our modern conception of fate and fatalism, readers of the play have a tendency to view Oedipus as a mere puppet controlled by greater forces. This, however, is inaccurate. While it is a mythological truism that oracles exist to be fulfilled, oracles merely predict the future. Neither they nor Fate dictate the future. In his landmark essay "On Misunderstanding the Oedipus Rex", E.R. Dodds draws a comparison with Jesus's prophecy at the Last Supper that Peter would deny him three times that night. Jesus knows that Peter will do this — but he in no way forces him to do it. Thus is the case with Oedipus.
The oracle delivered to Oedipus is often called a "self-fulfilling prophecy", in that the prophecy itself sets in motion events that conclude with its own fulfillment. This, however, is not to say that Oedipus is a victim of fate and has no free will. The oracle inspires a series of specific choices, freely made by Oedipus, which lead to kill his father and marry his mother. Oedipus chooses not to return to Corinth after hearing the oracle, just as he chooses to head toward Thebes, to kill Laius, to marry and to take Jocasta specifically as his bride; in response to the plague at Thebes, he chooses to send Creon to the Oracle for advice and then to follow that advice, initiating the investigation into Laius's murder. None of these choices were predetermined.
Another characteristic of oracles in myth is that they are almost always misunderstood by those who hear them; hence Oedipus's misunderstanding the significance of the Delphic Oracle. He visits Delphi to find out who his real parents are and assumes that the Oracle refuses to answer that question, offering instead an unrelated prophecy which forecasts patricide and incest. Oedipus's assumption is incorrect: the Oracle does answer his question. Stated less elliptically, the answer to his question reads thus: "Polybus and Merope are not your parents. You will one day kill a man who will turn out to be your biological father. You will also one day marry, and the woman whom you choose as your bride will be your real mother."
"So, you mock my blindness? Let me tell you this. You [Oedipus] with your precious eyes, you're blind to the corruption of your life..."
(Robert Fagles 1984)''