Final answer:
Whitman's introduction sets a celebratory tone reflecting themes of democracy and individualism, merging images of the natural and urban worlds. His free verse challenges traditional poetry structures, establishing a relaxed, contemplative mood, and addressing themes like the Civil War, making his work resonate over time.
Step-by-step explanation:
Walt Whitman's introduction in his poetry, particularly in Leaves of Grass, serves not only to set the tone but also establishes themes of democracy and individualism. His use of free verse was revolutionary at the time, challenging readers to move beyond the structured formats of rhyme and meter. In his works, imagery from the natural world often stands toe-to-toe with urban and manmade elements, showcasing a unique juxtaposition that reflects the expansiveness of America. Song of Myself, with its celebratory voice and the blending of daily life, exemplifies his ethos. The focus on the 'common people' and his commentary on the easiness of daily life, as seen in the lines "I loafe and invite my soul,/I lean and loafe at my ease observing a spear of summer grass," evokes a mood of relaxation and contemplation that was quite radical at the time.
Whitman's work, including his engagement with the Civil War through poems like "O Captain! My Captain!", resonates through ages due to its foundational qualities of embracing change and modernization. The idea that the true spirit of America lies within its ordinary citizens is a constant through thread in his poetry which often sublime the everyday to the extraordinary. This was quite shocking in 1855 when such notions challenged the established societal norms.