The utter wo and despair of Io are finely contrasted with the stern spirit of Prometheus.

Her introduction gives rise to those ancestral and traditionary allusions to which the Greeks were so attached.

In prophesying her fate, Prometheus enters into much beautiful descriptive poetry, and commemorates the lineage of the Argive kings.

After Io's departure, Prometheus renews his defiance to Jupiter, and his stern prophecies, that the son of Saturn shall be "hurled from his realm, a forgotten king." In the midst of these weird denunciations, Mercury arrives, charged by Jupiter to learn the nature of that danger which Prometheus predicts to him.

The Titan bitterly and haughtily defies the threats and warnings of the herald, and exults, that whatever be his tortures, he is at least immortal,-- to be afflicted, but not to die.