What ultimate realization does Oedipus come to in the play?

Oedipus ultimately realizes that he has caused his own downfall, making this choice the focal point of his tragic journey. Throughout the play, Oedipus is portrayed as a proud and determined king who seeks to rid Thebes of the plague by uncovering the truth about King Laius's murder. As the narrative unfolds, it becomes increasingly evident that his relentless pursuit of the truth leads him to a devastating self-discovery.

This realization is significant because it embodies the central theme of fate versus free will. Oedipus's downfall is not merely due to external forces or the prophecies that foretold his tragic fate; rather, it is his own actions and decisions—born out of his hubris and determination to defy fate—that lead to catastrophic consequences. By the end of the play, Oedipus understands that his attempts to escape his destiny have inadvertently set it in motion.

This deep and poignant acknowledgment of personal responsibility is at the heart of Oedipus's character arc, illustrating the tragic irony of his situation. It serves as a powerful commentary on the nature of human existence and the often harsh realities of knowledge and self-awareness.