The Oresteia: Agamemnon, the Libation-Bearers & the Furies by Aeschylus

has revolted against the Prophet can she prophesy what is to come. Not until she bares herself to the Furies can she foresee the coming of Orestes - the promise of the future rising from the torment of the present:
    We will die,
but not without some honour from the gods.
There will come another to avenge us,
born to kill his mother, born
his father’s champion. A wanderer, a fugitive
driven off his native land, he will come home
to cope the stones of hate that menace all he loves.
The gods have sworn a monumental oath: as his father lies
upon the ground he draws him home with power like a prayer.
    This is Cassandra’s first constructive prophecy, her first to be believed, and through it she herself becomes empowered. Now her death fulfils her with a strength she offers to the elders. She approaches the doors, she smells the reek of blood and cries, but she turns her cry into evidence that can convict her murderers in a later court of law, like the Areopagus towards which the Oresteia turns. Cassandra has a genius for conversions. She converts destructive images into their opposites: she is a bride of death like Iphigeneia. but she bears a prophecy that lives. In her closing lines she turns her personal misery into a vision of the human condition. She has suffered into truth. Under Apollo she is the Peitho that is pathos ; under the Furies she acquires mathos too, the Peitho of compassion. She has turned the Furies’ harsh incriminations into kindness - a prophetic turning-point indeed. Through Cassandra we turn from the eagles killing the mother hare, the father killing the daughter, and the warlord razing Aphrodite’s Troy, to the queen who kills the king, and the mother’s vengeance that pursues the son until this clash between male and female is resolved in the union of Athena and the Eumenides, Zeus and Fate. It is a turn, in short, that is creative as well as destructive, like Cassandra’s growing kinship with the queen. Both are destined to be murdered, yet as they die they may predict a crucial balance. Cassandra sees that Orestes must be ‘born to kill his mother’ - her Fury must impel him in his mission. That will be the crux of the trilogy, yet even at this point, while summoning Clytaemnestra’s vengeance, Cassandra surrounds it with the aura of its offspring, justice. She is both the victim of the queen and her vitality, the Eumenides in Clytaemnestra’s Fury. Cassandra is the redemptive heart of the Oresteia. She is the agony of vision. She is the tragic muse.
    Throughout the trilogy Aeschylus will dramatize her power. As she goes to her death, the chorus can finally accept Agamemnon’s murder and its cause: his excess, and his place in a great triad of murders, his father’s, his own, and soon his wife’s, ‘a threefold hammer blow’ like the three blows about to be dealt by Clytaemnestra. When the death-cries of the king ring out, the old men are terrified ; they scatter into individual voices - daring, cautious or disengaged - but a majority favours what Cassandra would have urged. They storm the doors to ‘see how it stands with Agamemnon’, and what they see unites them once and for all.
    Rising over the bodies of the king and the seer, Clytaemnestra speaks the truth at last, magnificent in her defiance as she reveals what lay behind her ironies: a murder as climactic as any in the Iliad, a welcome more perverse than any in the Odyssey. As she re-enacts the trapping and the killing of the king, she impersonates Artemis the Huntress in effect, but she rebels against her fellow Olympians, she devotes her victim to Zeus, whom she demotes to the God of Death, and triumphs over Agamemnon:
    So he goes down, and the life is bursting out of him -
great sprays of blood, and the murderous shower
wounds me, dyes me black and I, I revel
like the Earth when the spring rains come down,
the blessed gifts of god, and the new green spear
splits the sheath and rips to birth in glory!
    Clytaemnestra represents