The Oresteia is a trilogy of tragedies about the end of the curse on the House of Atreus, written by Aeschylus.
It is the only surviving trilogy of ancient Greek plays, although the fourth satyr play that would have been performed with it has not survived. The trilogy was originally performed at the Dionysia festival in Athens in 458 BC, where it won first prize.
Agamemnon details the return of Agamemnon, King of Argos, from the Trojan War to his death. Waiting at home for him is his wife, Clytemnestra, who has been planning his death as revenge for the sacrifice of their daughter, Iphigenia. Furthermore, in the ten years of Agamemnon's absence, Clytemnestra has entered into an adulterous relationship with Aegisthus, Agamemnon's cousin and the scion of a dispossessed branch of the family, who is determined to regain the throne he believes should rightfully belong to him.
The play opens to Clytemnestra awaiting the return of her husband, having been told that the mountaintop beacons have given the sign that Troy had fallen. Though she pretends to love her husband, she is furious that he sacrificed their daughter, Iphigenia. This is not made clear here, but it would have been familiar to the audience. A servant stands on top of the roof, reporting that he has been crouching there "like a dog" (kunothen) for years, "under the instruction of a man-hearted woman." He laments the fortunes of the house, but promises to keep silent: "A huge ox has stepped onto my tongue." However, when Agamemnon arrives in his chariot, he has on board the prophetess Cassandra as a slave and concubine. This, of course, serves to anger Clytemnestra further.
The main action of the play is the agon between Clytemnestra and Agamemnon. She attempts to persuade Agamemnon to step on a purple (sometimes red) tapestry or carpet to walk into their home. The problem is that this would indicate hubris on Agamemnon's part, and he does not wish to do this. Eventually, for reasons that are still heavily debated, Clytemnestra does convince Agamemnon to enter the oikos, where she kills him in the bath: she ensnares him in a robe and as he struggles to free himself she hacks him with three strokes of a pelekus. Agamemnon is murdered in much the same way as an animal killed for sacrifice with three blows, the last strike accompanied by a prayer to a god.
Whilst Clytemnestra and Agamemnon are offstage, Cassandra discusses with the chorus whether or not she ought to enter the palace, knowing that she too will be murdered. Cassandra is a daughter of King Priam of Troy. Apollo has cursed her, giving her the gift of clairvoyance, but on the condition that no one who heard her prophesies would believe them. In Cassandra's speech, she runs through many gruesome images of the history of the House of Atreus, and eventually chooses to enter the house knowing that she cannot avoid her fate. The chorus, in this play a group of the elders of Argos, hear the death screams of Agamemnon, and frantically debate on a course of action.
A platform is soon rolled out displaying the gruesome dead bodies of Agamemnon and Cassandra, along with Clytemnestra, who attempts to explain her action. Later, Aegisthus struts out and delivers an arrogant speech to the chorus, who nearly enter into a brawl with Aegisthus and his henchmen. However, Clytemnestra halts the dispute, saying that "There is pain enough already. Let us not be bloody now." The play closes with the chorus reminding the usurpers of Orestes, the son of Agamemnon, who will surely return to exact vengeance.
In the palace of Argos, Clytemnestra, who now shares her bed and the throne with her lover Aegisthus, is roused from slumber by a nightmare: she dreamt that she gave birth to a snake, and the snake now feeds from her bosom and draws blood instead of milk. Alarmed by this, a possible sign of the gods' wrath, she orders her daughter, the princess Electra, whom in the meantime Clytemnestra has reduced to the virtual status of a slavegirl, to pour libations on Agamemnon's grave. A group of women (the libation bearers of the title) are to assist her.
Electra arrives at the grave of her father and comes upon a man by the tombstone, who has just placed a lock of his hair on the stone. As they start to speak, it gradually and rather agonizingly becomes apparent that the man is her brother Orestes (who had been sent away to the royal court of Phocis since infancy for safety reasons), and who has, in her thoughts, been her only hope of revenge. Together they plan to avenge their father by killing their mother Clytemnestra and her new husband, Aegisthus.
Orestes wavers about killing his own mother, but is guided by Apollo and his close friend Pylades, the son of the king of Phocis, that it is the correct course of action. Orestes and Pylades pretend to be ordinary travellers from Phocis, and ask for hospitality at the palace. They even tell the Queen that Orestes is dead. Delighted by the news, Clytemnestra sends a servant to summon Aegisthus. Orestes kills the usurper first, and then his mother. As soon as he exits the palace, the Furies appear and, being only visible to him, they begin to haunt and torture him for his crime. He flees in agony.
The Eumenides (also known as The Furies) is the final play of the Oresteia, in which Orestes and the Furies go before a jury of Athenians, the Areopagos (Rock of Ares, a flat rocky hill by the Athenian agora where the supreme criminal court of Athens held its sessions), to decide whether Orestes' murder of his mother, Clytemnestra, makes him worthy of the torment they have inflicted upon him.
Orestes is tormented by the Furies, chthonic deities that avenge patricide and matricide. He, at the instigation of his sister Electra and the god Apollo, has killed their mother Clytemnestra, who had killed their father, King Agamemnon, who had killed his daughter and their sister, Iphigenia. Orestes finds a refuge and a solace at the new temple of Apollo in Delphi, and the god, unable to deliver him from the Furies' annoying wrath, sends him along to Athens under the protection of Hermes, while he casts a drowsy spell upon the pursuing Furies in order to delay them.
Clytemnestra's ghost appears from the woods and rouses the sleeping Furies, urging them to continue hunting Orestes. The Furies' first appearance on stage is haunting: they hum a tune in unison as they wake up, and seek to find the scent of blood that will lead them to Orestes' tracks. Ancient tradition says that on the play's premiere this struck so much fear and anguish in the audience, that a pregnant woman named Neaira died on the spot.
The Furies' tracking down of Orestes in Athens is equally haunting: Orestes has clasped Athena's small statue in supplication, and the Furies close in on him by smelling the blood of his slain mother in the air. Once they do see him, they can also see rivulets of blood soaking the earth beneath his footsteps.
As they surround him, Athena intervenes and brings in a jury of twelve Athenians to judge her supplicant. Apollo acts as attorney for Orestes, while the Furies act as spokespersons for the dead Clytemnestra. The trial results in a hung jury and Athena breaks the tie by voting in favour of Orestes, and then must persuade the Furies to accept her decision. They eventually submit. (However, in Euripides' Iphigeneia in Tauris, the Furies continue to haunt Orestes even after the trial.) Athena then renames them Eumenides (Ladies of Good Will). The Furies will now be honored by the citizens of Athens and ensure their prosperity. Athena also declares that henceforth hung juries should result in the defendant being acquitted, as mercy should always take precedence over harshness.
That the play ends on a happy note may surprise modern readers, to whom the word tragedy denotes a drama ending in misfortune. The word did not carry this meaning in ancient Athens, and many of the extant Greek tragedies end happily.
Worth noting here is the metaphorical aspect of this play. The change from an archaic method of justice by personal revenge to attribution of justice by trial is highly symbolic of the passage from a primitive society governed by instincts, to a modern society governed by reason: justice is decided by a jury of peers, representing the citizen body and its societal values, and the gods themselves sanction this transition by taking part in the judicial procedure, arguing and voting on an equal footing with the mortals. This theme of the polis self-governed by consent through lawful institutions, as opposed to tribalism and superstition, is a recurring one in Greek art and thought.
The dramatization of societal transformation in this myth (the transition to governance by laws) is both a boast and justification of the then relatively new judicial system. The concept of objective intervention by an impartial entity against which no vengeance could be taken (the state) marked the end of continuous cycles of bloodshed, a transition in Greek society reflected by the transition in their mythology--the Furies are a much greater part of older Greek myths than comparatively more recent ones. The reflection of societal struggles and social norms in mythology makes plays like these of special interest today, offering poignant cultural and historical insights.