Further progress in dramatic art has been made in this play. One of the main sources of the pathos of human life is the operation of what seems to us to be mere blind chance. Just as the casual dropping of Desdemona's handkerchief gave Iago his opportunity, so the casual allotting of the seven gates brings the two brothers into conflict. But behind it was the working of an inherited curse; yet Aeschylus is careful to point out that the curse need never have existed at all but for the wilfulness of Laius; he was the origin of all the mischief, obstinately refusing to listen to a warning thrice given him by Apollo. Another secret of dramatic excellence has been discovered by the poet, that of contrast. Two brothers and two sisters are balanced in pairs against one another. The weaker sister Ismene laments the stronger brother, while the more unfortunate Polyneices is championed by the more firmly drawn sister. Equally admirable is the contrast between the righteous Amphiaraus and his godless companions. The character of each of these is a masterpiece. War, horror, kindred bloodshed, with a promise of further agonies to arise from Antigone's resolve are the elements which Aeschylus has fused together in this vivid play. "There was war in Heaven" between the new gods and the old. The _Prometheus Bound_ contains the story of the proud tyranny of Zeus, the latest ruler of the gods. Hephaestus, the god of fire, opens a conversation with Force and Violence who are pinning Prometheus with chains of adamant to the rocks of Caucasus. Hephaestus performs his task with reluctance and in pity for the victim, the deep-counselling son of right-minded Law. Yet the command of Zeus his master is urgent, overriding the claims of kindred blood. Force and Violence, full of hatred, hold down the god who has stolen fire, Hephaestus' right, and given it to men. They bid the Fire-God make the chains fast and drive the wedge through Prometheus' body. When the work is done they leave him with the taunt: "Now steal the rights of the gods and give them to the creatures of the day; what can mortals do to relieve thy agonies? The gods wrongly call thee a far-seeing counsellor, who thyself lackest a counsellor to save thee from thy present lot." Abandoned of all, Prometheus breaks out into a wild appeal to earth, air, the myriad laughter of the sea, the founts and streams to witness his humiliation; but soon he reflects that he had foreseen his agony and must bear it as best he can, for the might of Necessity is not to be fought against. A sound of lightly moving pinions strikes his ears; sympathisers have come to visit him; they are the Chorus, the daughters of Ocean, who have heard the sound of the riveted chains and hurried forth in their winged car Awestruck, they come to see how Zeus is smiting down the mighty gods of old. It would be difficult to imagine a more natural and touching motive for the entry of a Chorus.