Who includes diversity and is Nature,
Who is the amplitude of the earth, and the coarseness and sexuality of the earth, and the great charity of the earth, and the equilibrium also,
Who has not look'd forth from the windows the eyes for nothing,
or whose brain held audience with messengers for nothing,
Who contains believers and disbelievers, who is the most majestic lover,
Who holds duly his or her triune proportion of realism,
spiritualism, and of the aesthetic or intellectual,
Who having consider'd the body finds all its organs and parts good,
Who, out of the theory of the earth and of his or her body
understands by subtle analogies all other theories,
The theory of a city, a poem, and of the large politics of these States;
Who believes not only in our globe with its sun and moon, but in
other globes with their suns and moons,
Who, constructing the house of himself or herself, not for a day
but for all time, sees races, eras, dates, generations,
The past, the future, dwelling there, like space, inseparable together.
The range of Whitman’s poem is naturally very wide, but he keeps the “other globes” relatable to us via one of his trademark repetitions. 
 The universe contains billions of planets and Whitman manages to convey the conflicting nature of the cosmos as being beyond our understanding, and at the same time relatable to our own existence. 
 For reference, this is how far outside our own backyard we’ve looked: 

Kosmos