I’ll likely need some judges to rule on my request for the entire work (tetralogy) as one work.  It was originally performed as such and was intended to illustrate a change in Athenian society.  If not allowed, I’ll keep the Agamemnon (first part) as it is the best known.  It is still on a few rare curriculums in universities and High Schools.
 22.02 PLAY The Oresteia by Aeschylus 
Although this work was written to tell the story of a fallen house , it actually is an affirmation of the fairly new the change in Athenian society to democracy after the destruction of the invading Persian army at Marathon (Aeschylus was actually a veteran of that famous battle.).  It specifically extols the importance of reason in the development of laws, and, lauds the ideals of a democratic Athens.  Written as a 4 part play (of which no copies survive of the 4th part Proteus),  it is in effect one larger work (similar to The Lord of The Rings as a trilogy).
Aeschylus ( c. 525 BC/524 BC – c. 456 BC/455 BC) was an ancient Greek playwright. He is often recognized as the father of tragedy, and is the earliest of the three Greek tragedians whose plays survive extant. According to Aristotle, he expanded the number of characters in plays to allow for conflict among them; previously, characters interacted only with the chorus.
The Oresteia is a trilogy of Greek tragedies which concerns the end of the curse on the House of Atreus. Though originally written as tetralogy, it is the only surviving example of a trilogy of ancient Greek plays; the fourth play, Proteus, a satyr play that would have been performed as finale, has not survived. The Oresteia was originally performed at the Dionysia festival in Athens in 458 BC, where it won first prize. Overall, this trilogy emblemizes the shift from a monarchal system of vendetta in Argos to a democratic system of litigation in Athens.
Agamemnon details the homecoming and eventual murder of Agamemnon, King of Argos, from the Trojan War.
The Libation Bearers is the second play of the Oresteia. It deals with the reunion of Agamemnon's children, Electra and Orestes, and their revenge.
The Eumenides (Εὐμενίδες, Eumenides; also known as The Furies) is the final play of the Oresteia, in which Orestes, Apollo, and the Erinyes go before Athena and a jury consisting of the Athenians at the Areopagus (Rock of Ares, a flat rocky hill by the Athenian agora where the homicide 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.
Although Proteus, the satyr play which originally followed the first three plays of The Oresteia, is lost, it is widely believed to have been based on the story told in Book IV of Homer's Odyssey, where Menelaus, Agamemmnon's brother, attempts to return home from Troy.
Worth noting here is the metaphorical aspect of this entire drama. Initially, in their role as avengers of bloodshed, the Erinyes are classical equivalents to the Code of Hammurabi and the Torah, which demand “an eye for an eye, a tooth for a tooth”. Thus, they initially embody the concept of lex talionis, or “law of retribution”.
The change from an archaic self-help justice by personal revenge or vendetta to administration of justice by trial symbolises 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 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, recurs 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 Erinyes 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.