Oedipus seeks knowledge, but only up to a point Sophocles' classical Greek tragedy Oedipus the King is one of the centre pieces of Western literature. It also has a broader place in modern Western culture, courtesy of Dr Freud and his Oedipus complex, in which the process of growing up male is bound up with competition for the mother and the symbolic overthrow and supplanting, or ''killing'', of the father. The play can be read as a traditional study of the 'fatal flaw'' theory of tragedy, in which Oedipus is brought down by hubris. Or as an object lesson in cautious, wise, mindful living, playing with the imagery of light and sight.

Or a statement about the nature of reality and truth, and the place of uncertainty and impermanence. Or even as the first detective story, complete with clues, red herrings, false leads and gradually mounting evidence. In this reading, Oedipus is not only the chief investigator and chief prosecutor, but the chief suspect as well. A deep and consistent feature of the play is irony. If we compare the opening scene with the closing scene, the irony of Oedipus's experience is stark.

At the beginning he is a powerful, commanding, regal figure with the interests of Thebes and its suffering citizens as his focus. By the end Oedipus is destitute, exiled by his own decree (''may he wear out his life in misery and miserable doom''), having promised to wipe out the source of the plague without realising he is the source, and that all the evidence will lead back to himself. At so many key points there is a sharp interplay between public knowledge and private awareness, or unconscious knowledge, which sets up great tension. This is part of the larger revelatory process that structures the play as a whole. The unfolding evidence takes centre stage in the key sequences and confrontations, and amid repeated patterns of imagery to do with darkness and light, blindness and sight, the value of knowledge and the ''plague'' of ignorance and infamy.

The Chorus is the voice of the Theban citizens, fearful and confused by the unfolding events. Oedipus is a man of action who takes on the responsibility of rescuing the people by anticipating certain moves. He sends Creon to consult the oracle of Apollo before being advised to do so, and learns that the murderer of the former King Laius is the cause of the plague and is in Thebes. He decides to reopen the unsolved case and calls in the reluctant Teiresias.

The blind seer reveals that Oedipus himself is the ''land's pollution'', but Oedipus dismisses his words. Prophecy is a motivating force and Teiresias knows of the child prophesied to kill his father and marry his mother - a tale that unites Thebes and Corinth and motivates decisions both in the house of Laius and in the mind of Oedipus, as he flees the home of his supposed parents. Oedipus's true identity is revealed bit by bit. Firstly as the murderer of King Laius, then as the abandoned child, and finally as both the child and husband of Jocasta. Among the main clues early on in the unravelling truth of identity and circumstance is the scene of the crime - ''the crossroads'', which prompts deeper associations followed by other coincidences and readings of signs.

The ''fatal flaw'' reading is still compelling. How much did Oedipus contribute to his own downfall? To some extent he is his own worst enemy and, paradoxically, his best qualities are closely related to his faults. Oedipus is perceived as a man who values knowledge but it is all about mastery, and he is relentless in the pursuit that brings about his self-destruction. He acts impulsively and pushes unwisely, is high-handed and arrogant. He is not consistently clear-sighted - for example, he does not take on board the implications of the rumour of his illegitimacy, and after visiting the oracle flees before finding out the key fact of whether Polypus and Me rope are his real parents. He displays paranoia and accuses Creon of ambition and sedition.

He is highly disrespectful to the revered Teiresias and provokes the truth out of him. Finally he is extravagant in all he does; even his final scenes are grandiose. Other key questions abound. What is the relationship between innocence and ignorance? Jocasta and Oedipus are both victims of circumstance, but Oedipus participates in his own tragedy differently, more actively and with more complexity. Jocasta struggles then tragically submits to defeat by the truth, compared with Oedipus's solution of self-punishment, sight-in-blindness and redemption through suffering. The Chorus closes with the statement that happiness is illusory and fragile, and can only be assessed at the very end of life.

Trying to control everything in life is futile. And the wisdom of pursuing full, rather than partial, knowledge to counteract some of the pain of life is made evident.