In "On First Looking into Chapman's Homer," how would you analyze the poem's conclusion?

The perfectly captured emotion of the conclusion to "On First Looking into Champman's Homer" sets this sonnet apart and, indeed, heralded the brilliance of Keats as a rising star among poets. John Keats, only twenty-one years old at the time, had stayed up all night reading a translation of The Odyssey that his mentor, Charles Cowden Clarke, introduced to him. After leaving Clarke's home at dawn, Keats wrote the sonnet and sent it off to Clarke, who received it by ten o'clock that morning. Keats's sonnet is widely acclaimed for its powerful metaphors and emotion.
The conclusion would not be so powerful if it didn't represent such a stark contrast to what precedes it. The sonnet compares the thrill of discovery through literature to the thrill of astronomical and intercontinental exploration. The canvas with which Keats paints the scene on is huge: a planet swims into the vision of an astronomer scanning the heavens; a Spanish expedition, after a grueling journey across water and through the jungle, arrives at a summit from which they can see the long-searched-for South Sea. This scene of movement and broad expanse then focuses on the eyes of the men and their expression—one of "wild surmise." The silence adds to the impact. The thrill of discovery takes their breath away. One can feel the bracing air of that mountaintop experience.
The last two lines break the prescribed iambic rhythm at the initial foot of each line. This is not a defect but instead gives the conclusion added effect, as if the steady march of the explorers halts in order to take in the joyous experience. The conclusion pays off. Readers can see, feel, and hear the explorers atop the mountain, and they can imagine their utter elation. Now readers realize that the poem isn't about Cortez's (actually Balboa's) discovery; instead, it represents how someone feels after reading a powerful work of literature. And that hits home. We all know that the beauty of a meaningful story, told through images, words, or music, can fill us with that same overwhelming sense of joy and wonder—the "wild surmise" of having new worlds opened to us.