The play is Titanic. Its huge shapes, its weird effects, its mighty passions, its wild display of the forces of earth and air,--these impress us chiefly at first; but its ethical interest is far greater. Zeus is apparently represented in it as relentless, cruel, and unjust,--a lawless ruler, who knows only his own will,--whereas in all the other plays of Aeschylus he is just and righteous, although sometimes severe. Aeschylus, we know, was a religious man. It seems incredible that he should have had two contradictory conceptions of the character of Zeus. The solution of this problem is to be found in the fact that this 'Prometheus' was the first play of the trilogy. In the second play, the 'Prometheus Unbound,' of which we have only fragments, these apparent contradictions must have been reconciled. Long ages are supposed to elapse between the plays. Prometheus yields. He reveals the secret and is freed from his bonds. What before seemed to be relentless wanton cruelty is now seen to have been only the harsh but necessary severity of a ruler newly established on his throne. By the reconciliation of this stern ruler with the wise Titan, the giver of good gifts to men, order is restored to the universe. Prometheus acknowledges his guilt, and the course of Zeus is vindicated; but the loss of the second play of the trilogy leaves much in doubt, and an extraordinary number of solutions of the problem has been proposed. The reader must not look for one of these, however, in the 'Prometheus Unbound' of Shelley, who deliberately rejected the supposition of a reconciliation. The three remaining plays are founded on the woful myth of the house of Atreus, son of Pelops, a theme much treated by the Greek tragic poets. They constitute the only existing Greek trilogy, and are the last and greatest work of the poet. They were brought out at Athens, B.C. 458, two years after the author's death. The 'Agamemnon' sets forth the crime,--the murder, by his wife, of the great King, on his return home from Troy; the 'Choëphori,' the vengeance taken on the guilty wife by her own son; the 'Eumenides,' the atonement made by that son in expiation of his mother's murder. Agamemnon on departing for Troy left behind him in his palace a son and a daughter, Orestes and Electra. Orestes was exiled from home by his mother Clytemnestra, who in Agamemnon's absence lived in guilty union with Aegisthus, own cousin of the King, and who could no longer endure to look upon the face of her son.