Although the poet sings of the self as "a simple separate person," he also sees it as part of "the word Democratic," which represents the mass of people. He sings of "the Form complete," the female as well as the male, of "Life immense in passion, pulse, and power," and the "Modern Man."
This small (nine-line) poem is really a preface to all the others in Leaves of Grass. Whitman says he will sing of all physiology (the branch of biology dealing with the functions and processes of living organisms), for neither the physiognomy (outward appearance) nor the brain is worthy of being celebrated independently. He lists the subjects and themes he will deal with: "One's-self" (the unit of self or individuality), "physiology . . . the Form complete" (the kinship of the body and the spirit which he will emphasize throughout Leaves), and "Life" — in short, the "Modern Man," who, according to Whitman, is conscious of "self" but at the same time is aware of being part of the large mass of democracy.
