What kind of human physiology does Whitman's Leaves of Grass entrust to the poet?

Leaves of Grass is Whitman's poetry collection. He began to write poetry in the 1940s. When the first edition of Leaves of Grass (1855) came out, it was only 95 pages and contained 12 poems. Although it is a thin collection of poems, it is the crystallization of the poet's life. After each new edition of Leaves of Grass, new poems will be added. By the time the ninth edition, the dying edition, was published in 1892, Leaves of Grass was already a masterpiece containing nearly 400 poems. The vibrant blade of grass is the poet's own image, symbolizing the thriving America, and endowing the poet with the ideal of democracy and freedom.