The first stanza of section 31 is one of the most lyrical sections of Walt Whitman's "Song of Myself." It introduces the reader to a variety of images of the natural world, all of which culminate in a celebration of simplicity and "insignificance."
Consider, for instance, that all of the images that Whitman uses refer to small pieces of nature that are often overlooked in favor of things deemed more dramatic. In lines 663-69, Whitman celebrates "a leaf of grass," a "pismire" (an ant), a "tree-toad," "the narrowest hinge in my hand," and, last but not least, a "cow crunching with depress'd head." Whitman celebrates all of these humble images of the natural world, although his assessment of the "leaf of grass" is perhaps his most significant, as he compares the vegetation to "the journey-work of the stars" (663).
It's apparent, therefore, that Whitman wants to assert the inherent importance of all things, of all the myriad pieces of the world. Furthermore, he deliberately equates humble and seemly insignificant things, such as grass and toads, with the glamour of the cosmos to argue that the infinite complexities and wonders of the universe are found even within the smallest of things. As such, this section becomes one of the most important parts of the poem, as it advances Whitman's thesis that each individual organism is "a kosmos" (497).