Oedipus Rex reveals the prophecy which caused him to leave Corinth (791-93): "that I was fated to lie with my mother," "and show to daylight an accursed breed" "which men would not endure, and I was doomed" "to be murderer of the father that begot me." The implication of Laius's oracle is ambiguous. One interpretation considers that the presentation of Laius's oracle in this play differs from that found in Aeschylus's Oedipus trilogy produced in 467 BC. Helaine Smith argues: Sophocles had the option of making the oracle to Laius conditional ("if" Laius has a son, that son will kill him) or
Oedipus Rex drunken guest on the other hand: you are not your father's son defines Polybus as only a foster father to Oedipus. The two wordings support each other and point to the "two set of parents" alternative. Thus the question of two set of parents, biological and foster, is raised. Oedipus's reaction to the Oracle is irrational: he states he did not get any answer and he flees in a direction away from Corinth, showing that he firmly believed at the time that Polybus and Merope are his real parents. "The scene with the drunken guest constitutes the end of Oedipus'