Keats has wide experience in the reading of poetry and is familiar with Homer's Iliad and Odyssey, but not until now has he had the special aesthetic enjoyment to be gained from reading Homer in the translation of George Chapman. For him, the discovery of Homer as translated by Chapman provides the same kind of overwhelming excitement felt by an astronomer who has discovered a new planet or by Cortez when he first saw the Pacific from a summit in Central America.
Keats composed his most famous sonnet when he was only twenty years old and had comparatively little experience in the writing of sonnets. The poem is brilliant testimony of the effect of poetry on Keats. He had spent a night in the autumn of 1816 reading poetry with his friend Charles Cowden Clarke, who introduced him to some of the best passages in George Chapman's translation of Homer. Keats was delighted with the vigorous language of the Elizabethan; to him, Chapman spoke out "loud and bold." After Keats left Clarke, around daybreak, he walked to his lodgings, sat down at his desk, wrote his tribute to Chapman, and had a copy of it on his friend's breakfast table by ten o'clock in the morning. The poem seems to have been composed in the white heat of excitement, in a flash of inspiration. Keats made very few changes in it, but the changes he made show that he realized that inspiration is not enough; it must be followed by critical judgment. Keats' changes in the poem are all improvements.
It is appropriate that the finest poem in Keats' first volume of poetry should be about poetry. At the time, poetry meant more to him than anything else in the world. He was on the point of giving up the security of a career in medicine for the uncertainties of a career in poetry. The first four lines of "Chapman's Homer" are a statement of the experience he has already had as a reader of poetry: "Much have I travell'd in the realms of gold . . ." In poetry he has found the gold that Cortez, and the other conquistadors he had read about in William Robertson's History of America, had searched for so feverishly. As Keats is still young, there are innumerable discoveries of "realms of gold" awaiting him. In "Chapman's Homer," he excitedly reports one such discovery.
To convey to the reader the thrill of discovery he has experienced in hearing his friend Clarke read from Chapman's Homer to him, he uses two smiles that are both beautiful and apt. "Then felt I like some watcher of the skies / When a new planet swims into his ken." The discovery of a new planet is so rare that only one had been made between ancient times and 1781, when Sir William Herschel discovered the planet Uranus. Keats, of course, may not have had Herschel in mind, but it was the rarity of such a discovery and the emotions which would overwhelm the discoverer that counted. Nothing less would give the reader an adequate idea of what happened to Keats when he "heard Chapman speak out loud and bold." "Swims," the verb used to describe the way in which a heavenly body would move into the circular lens of an astronomer's telescope, suggests perfectly the motion of a planet as seen from the earth.
The second simile used by Keats is unquestionably the most impressive part of the sonnet. It is made up of a number of details that fit together into an artistically pleasing whole. Cortez is "stout," that is, fearless, and he is alert, "with eagle eyes." Only men such as he discover Pacific Oceans. His men stand about him in silent awe, looking "at each other with a wild surmise." Their imaginations are flooded by a bewildering variety of guesses as to what lies beyond the horizon, new Americas perhaps, filled with gold and fabulous jewels and untold possibilities of further discoveries. They are so choked with emotion that they cannot speak. This is one of the great moments of history, and Keats boldly appropriates it to express his own feelings of having made a thrilling discovery beyond which there may lie countless other similar discoveries as he increases his acquaintance with the world of poetry.
The two similes that swam "into his ken" as the poem formed itself in his mind are in keeping with the language of travel and discovery that he uses in the octave of his sonnet. They give it a unity of imagery that makes of the whole a tightly knit statement of what was for Keats, ardent lover of poetry that he was, a profoundly felt experience.
A Petrarchan sonnet must not only be unified, like any other poem, but the thought must also make a change of direction, or "turn," at the beginning of the sestet. Keats' turn is his two comparisons taken from astronomy and exploration. Unity and coherence are assured not only by carrying the idea of discovery all the way through the poem, but also by using the linking words "Much" and "Oft" to begin the two halves of his octave and the word "Then" to begin his sestet. Keats, in spite of his limited experience in sonnet writing before "Chapman's Homer," composed what is probably one of the finest Petrarchan sonnets in English poetry.
In his excitement, Keats substituted the name of Cortez for Balboa in his sonnet. In his school days he had read about Cortez' conquest of Mexico and Balboa's discovery of the Pacific Ocean on an expedition in Darien, an old name for part of Central America, in William Robertson's History of America. In search of a historical example of an exciting discovery, Keats put Cortez where historically Cortez never was and made him seem to be the discoverer of the Pacific Ocean. It is not known whether Keats or any of his friends ever became aware of the error. It is a slight blemish in a fine poem, but, as many critics have pointed out, in poetry one looks for truth in human nature rather than for historical truth. Ideally, both should go together.