Much have I travelled in the realms of gold
And many goodly states and kingdoms seen;
Round many western islands have I been
Which bards in fealty to Apollo hold.
Oft of one wide expanse had I been told
That deep-browed Homer ruled as his demesne;
Yet did I never breathe its pure serene
Till I heard Chapman speak out loud and bold:
Then felt I like some watcher of the skies
When a new planet swims into his ken;
Or like stout Cortez when with eagle eyes
He stared at the Pacific—and all his men
Looked at each other with a wild surmise—
Silent, upon a peak in Darien.
Keats creates a small drama to suggest the astonishment of the explorers. The ‘wild surmise’ describes their attempt to make sense of the vastness of what they can see and to try to reationalise it, but fail. It is of course an  oxymoron .