Greek tragedy is said to develop itself from the group of dancers and singers who used to partake in the worship of various gods. According to Aristotle the Chorus should be like one of the characters. Gradually the role of the Chorus became less and less important in classical tragedy, until in Roman tragedy the speeches of the Chorus were supposed to be made in between the acts.
Chorus discharges some broad functions in all classical tragedies. The structure of a Greek tragedy is determined by the Chorus. After the prologue, it is with the entry of the Chorus that a Greek tragedy begins. Various episodes are also marked off by choric odes. The conclusion of a Greek tragedy occurs with the exode or the exit song of the Chorus. It is the function of the Chorus to comment on actions and events. It also sometimes questions the characters. Its standard role is that of the moderator. At times it represents the view-point of the common spectator and in some cases it represents the view-point of the dramatist himself.
The functions of the Chorus are very well performed in Oedipus Rex. In the very first ode the Chorus depicts the horror of the plague and expresses an apprehension about the message from the oracle of Delphi. Other odes comment on the action that has taken place after the last ode and build an atmosphere appropriate to that stage of the play. It plays the role of a peace-maker between the king and Creon and succeeds in getting the king's pardon for the latter. After the exit of Teiresias it comments on the terrible predictions which Teiresias has made but shows determination to support the king. Its most significant response is when Oedipus and Jocasta have expressed irreverent thoughts against the oracles. At many other times also they reflect the dominant mood and help to deepen it. When Oedipus imagines that he is the son of the goodness of luck, the Chorus, immediately sing that their master, Oedipus, might be the son of Apollo.
In the fifth or last choric ode in Oedipus Rex, the Chorus reflects the dejection of Oedipus and says that all the generations of moral man add up to nothing. This ode must not be regarded as reflecting the final mood and impression of the play, for the impression is as much of the greatness of the human spirit as of the insignificance of man and the transitoriness of his happiness. This ode must, therefore, be looked upon only as reflecting a final judgment of it. Oedipus remains forceful even in his downfall; in a sense he is still heroic.
The Chorus takes part in the dialogues also. When Oedipus consults them about ending the plague in the city, they express disappointment that the oracle had not guided them about the identity of Laius' murderer. They also tell him what they know about the murder of their previous king and its circumstances. When Creon, learning that the king has accused him of treason, comes on the stage he talks to the Chorus, who tell him that the king's accusation was probably made in the heat of anger. Creon asked if the king looked absolutely serious while making the charge and they rightly say that it is not for them to look into the eyes of his master when he speaks. When Oedipus has almost passed a sentence upon Creon, Jocasta arrives on the scene and first talks to the Chorus. They request her to settle the difference between the two men. They are worried when they see Jocasta going into the palace in a very dejected mood, and they give expression to their apprehension. Oedipus asks them about the shepherd who gave the infant to the Corinthian, they answer that his queen would be able to answer the question better. They sympathize with Oedipus when they see him after he has blinded himself. It is clear, thus, that the Chorus never takes a direct hand in the action. It does not consist only of spectators but influences the action in various subtle ways.
The contribution of the Chorus in Oedipus Rex is considerable. They link the play with common humanity. In some sense they are often in the position of the ideal spectator. They fill in the gaps in the action when no other character is there on the stage. They add to it the element of melody which must have been one of the attractions of Greek tragedy. They provide an appropriate shift between the titanic, heroic figure of Oedipus and the mass of common humanity represented by the two shepherds in Oedipus Res. The tragedy of Oedipus and its relevance to common life is very well stressed by the Chorus in its exit ode or exode.