The "him" for whom the poet sings is his ideal man of imagination and vision. "I raise the present on the past," Whitman says, comparing this process to the growth of a tree from its roots. He also depicts, he says, the ideal man's movement in space and in time. He is a "law unto himself."
This poem is cryptic and vague. "Him" is an ambivalent pronoun — no antecedent noun is stated for it. We must infer for whom the poet sings. The person for whom Whitman has greatest admiration is the embodiment of his ideal of personality. He is the thinking man, the man of vision. Whitman believes that the poet is able to unite the past with the present. Past and present are inseparable because they are part of the flow of time. Poetry, like a tree, grows organically and inwardly. The growth of personality is also organic and unified.
This short poem has a symbolic quality, though the poetic utterance is oblique and cryptic. The poet's function in uniting past and present is one of the basic ideas of Whitman's concept of poetry.