what is it?

Here is the efflux of the soul,
The efflux of the soul comes from within through embower'd gates, ever provoking questions,
These yearnings why are they? these thoughts in the darkness why are they?
Why are there men and women that while they are nigh me the sunlight expands my blood?
Why when they leave me do my pennants of joy sink flat and lank?
Why are there trees I never walk under but large and melodious thoughts descend upon me?
(I think they hang there winter and summer on those trees and always drop fruit as I pass;)
What is it I interchange so suddenly with strangers?

-- Walt Whitman, from "Song of the Open Road"

Song of the Open Road