I think I could turn and live with animals,
     they are so placid and self-contain’d,
I stand and look at them long and long.

They do not sweat and whine about their condition,
They do not lie awake in the dark and weep for their sins,
They do not make me sick discussing their duty to God,
Not one is dissatisfied, not one is demented
     with the mania of owning things,
Not one kneels to another, nor to his kind that lived
     thousands of years ago,
Not one is respectable or unhappy over the whole earth.

-Walt Whitman, Song of Myself 32

When Whitman talks about all that kneeling and weeping and whining and mania, he’s talking about Human Children. When he’s admiring the animals that are free of these qualities, he’s talking about Human Adults.