There remains one Aeschylean play, the most famous—unless we except the _Agamemnon_—in extant Greek literature, the _Prometheus Bound_. That it was the first of a Trilogy, and that the second and third parts were called the _Prometheus Freed_, and _Prometheus the Fire-Bearer_, respectively, is accepted: but the date of its performance is unknown. The _Prometheus Bound_ is conspicuous for its gigantic and strictly superhuman plot. The _Agamemnon_ is human, though legendary the _Prometheus_ presents to us the gods of Olympus in the days when mankind crept like emmets upon the earth or dwelt in caves, scorned by Zeus and the other powers of heaven, and—still aided by Prometheus the Titan—wholly without art or science, letters or handicrafts. For his benevolence towards oppressed mankind, Prometheus is condemned by Zeus to uncounted ages of pain and torment, shackled and impaled in a lonely cleft of a Scythian precipice. The play opens with this act of divine resentment enforced by the will of Zeus and by the handicraft of Hephaestus, who is aided by two demons, impersonating Strength and Violence. These agents of the ire of Zeus disappear after the first scene, the rest of the play represents Prometheus in the mighty solitude, but visited after a while by a Chorus of sea nymphs who, from the distant depths of ocean, have heard the clang of the demons’ hammers, and arrive, in a winged car, from the submarine palace of their father Oceanus. To them Prometheus relates his penalty and its cause: viz., his over tenderness to the luckless race of mankind. Oceanus himself follows on a hippogriff, and counsels Prometheus to submit to Zeus. But the Titan who has handled the sea nymphs with all gentleness, receives the advice with scorn and contempt, and Oceanus retires. But the courage which he lacks his daughters possess to the full; they remain by Prometheus to the end, and share his fate, literally in the crack of doom. But before the end, the strange half human figure of Io, victim of the lust of Zeus and the jealousy of Hera, comes wandering by, and tells Prometheus of her wrongs. He, by his divine power, recounts to her not only the past but also the future of her wanderings. Then, in a fresh access of frenzy, she drifts away into the unknown world. Then Prometheus partly reveals to the sea maidens his secret, and the mysterious cause of Zeus’ hatred against him—a cause which would avail to hurl the tyrant from his power. So deadly is this secret, that Zeus will, in the lapse of ages, be forced to reconcile himself with Prometheus, to escape dethronement. Finally, Hermes, the messenger of Zeus, appears with fresh threats, that he may extort the mystery from the Titan. But Prometheus is firm, defying both the tyrant and his envoy, though already the lightning is flashing, the thunder rolling, and sky and sea are mingling their fury. Hermes can say no more; the sea nymphs resolutely refuse to retire, and wait their doom.