The Greek tragedies were meant to show a protagonist of high birth struggling with a significant character flaw as he navigated an important experience in his life. These characters and stories were most often drawn from Greek history and mythology. Sophocles wrote one of Western literature's most famous tragedies "Oedipus Rex," about a king of Thebes. The Oresteia --"Agamemnon," "The Libation Bearers" and "The Eumenides" -- a trilogy of plays written by Aeschylus, told the story of King Agamemnon's return home from the Trojan War, his murder by his wife Clytemnestra and the avenging of his death by his children Electra and Orestes.
Aristotle stated that the tragic hero must be of noble birth and within the course of the play experience a tragic downfall due to an inborn flaw the character possesses, not some external circumstance. In this way, the hero undergoes a psychological transformation, teaching him a lesson about his own flawed nature. Aristotle believed that the downfall of the hero was important for the audience to witness, since they were usually of a more humble birth, but could be moved to "fear and pity" at the sight of the high-born hero's undoing. The audience would then experience an empathetic and cathartic emotional connection to the character's experience. King Oedipus, in the play "Oedipus Rex," is considered to be the quintessential tragic hero.
The chorus of a Greek tragedy was usually comprised of a group of men or women whose position in life was humble compared to the more central characters of the play. The chorus often commented on the choices and actions of the main characters, speaking or singing directly to the audience. They also invoked the intercession of the gods and prayed for assistance regarding the events of the play. For the ancient Greeks, the idea that the gods controlled all of life's events, that no man had freedom to decide his own fate, was central and the chorus often reminded the play's characters and the audience of this belief.
Aristotle's "Poetics" required a tragedy to unfold within a unified time and place, all scenes happening in the same location in continuous time. This placed an urgency upon the play's protagonist; events continued to happen with no time for the characters to pause and reflect on what they should or should not do. They simply made choices and moved forward, as people frequently do in real life. The unity of place required the play to remain focused on the specified location, often requiring information from other locations to be delivered by messengers and allowing violent events to be enacted off-stage.