The poem "Song of Myself", by Walt Whitman, is considered a free verse poem because of the following characteristic: It isn't built from specific rhyme metrics. Its verses seem like prose speech, they are almost like statements. The poem doesn't have any kind of metric, as it can be observed in this passage:
"Creeds and schools in abeyance,
Retiring back a while sufficed at what they are, but never forgotten,
I harbor for good or bad, I permit to speak at every hazard,
Nature without check with original energy".
During the entire poem, no rhymes match. That is a typical characteristic of free verse poems. Therefore, the characteristic that makes "Song of Myself" a free verse poem is its lack of rhymes that follow a metric.
