Final answer:
In "O Captain! My Captain!" Whitman's use of rhyme emphasizes contrasting themes of public victory versus private mourning, particularly manifesting in the poem's reflection on Lincoln's death following the Civil War.
Step-by-step explanation:
The poem "O Captain! My Captain!" by Walt Whitman utilizes rhyme to create emphasis on words that contribute to the overarching themes of loss and reverence. The rhyming pairs such as "done" and "won," "bells" and "trills," as well as "head" and "dead" draw attention to the poem's dichotomy of victory and death. The emphasis on these words deepens the contrast between the public triumph and private grief, further emphasized by the juxtaposition of the celebration for the end of the Civil War and the mourning of President Lincoln's assassination, which the Captain symbolizes. Additionally, the repetition of heart in "But O heart! heart! heart!" underscores the profound grief experienced by the speaker, reinforcing the theme of personal loss amidst a collective victory. The poem's structure and rhyming pattern provide a sense of familiarity and rhythm that contrast sharply with its somber content.