Anagnorisis
Anagnorisis is a moment in a play or other work when a character makes a critical discovery. Anagnorisis originally meant recognition in its Greek context, not only of a person but also of what that person stood for. Anagnorisis was the hero's sudden awareness of a real situation, the realization of things as they stood, and finally, the hero's insight into a relationship with an often antagonistic character in Aristotelian tragedy.
Tragedy
In his Poetics, Aristotle discussed peripeteia. In this work, he defined anagnorisis as "a change from ignorance to knowledge, producing love or hate between the persons destined by the poet for good or bad fortune". Anagnorisis is often discussed along with Aristotle's concept of catharsis.In the Aristotelian definition of tragedy, it was the discovery of one's own identity or true character or of someone else's identity or true nature by the tragic hero.
Aristotle was the first writer to discuss the uses of anagnorisis, with peripeteia caused by it. He considered it the mark of a superior tragedy, as when Oedipus killed his father and married his mother in ignorance, and later learned the truth, or when Iphigeneia in Tauris realizes in time that the strangers she is to sacrifice are her brother and his friend, and refrains from sacrificing them. Aristotle considered these complex plots superior to simple plots without anagnorisis or peripeteia, such as when Medea resolves to kill her children, knowing they are her children, and does so.
Another prominent example of anagnorisis in tragedy is in Aeschylus's "The Choephoroi" when Electra recognizes her brother, Orestes, after he has returned to Argos from his exile, at the grave of their father, Agamemnon, who had been murdered at the hands of Clytemnestra, their mother. Electra convinces herself that Orestes is her brother with three pieces of evidence: a lock of Orestes's hair on the grave, his footprints next to the grave, and a piece of weaving that she embroidered herself. The footprints and the hair are identical to her own. Electra's awareness is of her brother's presence, who is the one person who can help her by avenging the death of their father.