In Hyperion, John Keats begins to tell the mythological story of the fall of the Titans at the hands of the Olympians. Hyperion, the Titan god of the sun, remains the only unfallen Titan at the beginning of the poem, but he is in grave danger, for the Olympian Apollo is out to defeat him. Keats never finishes his grand epic. He stops in the midst of book 3, right as Apollo is shrieking out in agony, apparently not liking what he must do, namely, overthrow Hyperion.
Keats explores several different themes in Hyperion. First, he examines the nature of hope and despair. Many of the Titans have plunged into despair, believing that their cause is hopeless. They remain in darkness, unable to move, yet some of them, especially Thea, reach out for hope, for Hyperion has not yet fallen. Clymene turns to her music for comfort. Oceanus, however, advices resignation and acceptance of the truth of their situation. This change is meant to happen.
This introduces another theme, that of destiny. The world changes. The generations pass. This is natural, even for Titans. The time of the Olympians has now arrived, and there really is nothing the Titans can do about it. They must simply move on and accept what they must. It is their fate. Apollo seems to realize this, too, and he isn't altogether happy with it. In fact, he seems to feel guilty about what he must do. It pains him, yet he recognizes the necessity of it. He is caught up in something much greater than himself, and there is no stopping it.
A third theme in this poem is the conflict between memory and innovation. In the unfinished book 3, Apollo speaks with Mnemosyne, memory. He asks what the universe is all about. He struggles with overthrowing the Titans, who represent the past and tradition, yet he must do so. Apollo must sing a new song, make new music, and usher in the future. Clymene recognizes this, too, for she hears the new music of Apollo overcoming her own. Perhaps if Keats would have finished the poem, he might have found a way to balance memory and innovation.