how sophocles achieves catharsis in oedipus rex

In literary aesthetics, catharsis is developed by the conjunction of stereotyped characters and unique or surprising actions or events over time. Throughout a play, we do not expect the nature of a character to change significantly; rather, preexisting elements are revealed in a relatively straightforward way, as the character faces these confrontations. This is clearly evident in Oedipus Rex, where King Oedipus is confronted with ever more outrageous actions, until the catharsis/emptying generated by the death of his mother-wife, and by his own act of self-blinding.

Different techniques have been used to provoke strong emotional expressions in the readers or spectators. The effect of surprise and unexpectedness could be used as the key factor that leads to catharsis. For example, in the Greek tragedy "Oedipus Rex", catharsis occurs at the end when king Oedipus, driven by the guilt of impermissibility of incest and the emptiness caused by the loss of his beloved mother, blinds himself.