Upon realizing the dangers of trying to deny his own human nature, Endymion suddenly discovers that the Indian maiden, his mortal counterpart, is really Diana, his immortal desire, in disguise.
In the end, Endymion learns that he can only rise above his mortal nature and achieve some kind of idealized existence if he first accepts “his natural sphere.” Keats’s point, as in other poems, is that any attempt to achieve an abstract ideal must begin with an acceptance of concrete human experience.
In book 4, Endymion reenacts the lesson of Glaucus.
Having met an Indian maiden, Endymion is torn between his love for this mortal woman and his idealized love for his immortal goddess.
That is the stuff of life; or at least it was the stuff of Keats’s difficult life.
All attempts to escape that condition through “an irritable reaching after fact and reason” can only result in a sorry self-deception and a diminishment of human experience.
One condition of Glaucus’s release is that he and Endymion must locate the bodies of all the lovers who have drowned at sea and restore them to life.
Only by engaging once again in the world of mortal actions can Glaucus escape the dreadful consequences of trying to escape his own mortality.
Glaucus, like Endymion, had once been satisfied with his existence as a mortal, but, aroused by “distemper’d longings,” he had transformed himself into a sea-god.
When he rejected the seductions of the sea witch, Circe, she chained him to the bottom of the sea for a thousand years.