Time in its aging course teaches all things.

Prometheus exclaims this line, number 981, after Hermes tells him that Zeus does not know the word "alas." Here HeHH"alas" stands as the exclamation of pity, and this quote brings together the play's emphases on friendship and time. Pity is sympathy with suffering friends, and it is a feeling unknown to Zeus because he does not honor friendships. His power is absolute, so friendships cannot be important to him. Zeus is described as a tyrant because he places so much faith in his power, believing that he may do as he pleases while all others must obey him. Zeus's certainty rests on the assumption that his power is eternal. Prometheus's defiance rests on the knowledge that Zeus's power will, in time, be challenged. Time is significant because its passage limits Zeus's arrogance. In the end, he will be forced to either reconcile with Prometheus or be destroyed. Prometheus knows that the passage of time is stronger than even Zeus, and Zeus's weakness lies in his failure to recognize this fact.