According to Aristotle, a tragedy must be an imitation of life in the form of a serious story, complete in itself among many other things. Oedipus is often presented as the perfect example of what a tragedy should be according to Aristotle's poetics. The reason being that Oedipus seems to correctly include all the concepts that Aristotle describes as inherent in dramatic tragedy. These elements include: the importance of intrigue, reversal and recognition, the unity of time, the cathartic purge and the evocation of pity and fear, the presence of a fatal flaw in the " hero” and the use of the law of probability. the plot should consist of “clearly defined problems that the characters must solve.” The main set of clearly defined problems posed to the character Oedipus is that he must find a way to avoid the prophecy. His actions afterward drive the plot, which leads to more problems later. The plot should be organized in chronological order and feature actions that take place both on and off stage. Events that occur offstage should be conveyed using narrative. In Oedipus, a messenger is used to recount the events that happened off-stage. Another element of Aristotle's drama was the three unities: the unity of time, which limits action in history; unity of place, which limits the unfolding of events around a general; and the unity of action that limits events to be linked as cause and effect. The setting of Oedipus Rex takes place in the city and the palace and does not leave this place, but if something happens elsewhere, the messenger relays the information. The time frame of this story also appears to be only about a day or so, which was prescribed in the unit of time. As for unity of action, the whole tragedy of Oedipus springs from the news that his so-called father, Polybus, has just died; the rest is just cause and effect. In Aristotle's Poetics it is said that everything violent must happen off stage; that the drama does not come from spectacle or gore, but must result from what the characters have done. Oedipus Rex is a good example of this technique because much of the story is relayed by the messenger. An example is when Oedipus stabs himself and when the queen commits suicide..