Analyzing a Passage

"This new interest was a valued novelty in whistling, which had just acquired from a Negro, and he was suffering to practice....It consisted in a peculiar bird-like turn, a sort of liquid warble...and he strode down the street with his mouth full of harmony and his soul full of gratitude."

Choosing this passage was pretty easy, obviously because you see that a human to being related to nature. The first description it gives is "it consisted in a peculiar bird-like turn" so Twain gives the implication of symbolism between human  and bird. This was a good way to put a picture in your head about the whistling that was going on. "A sort of liquid warble" describes the character even more as a bird because a warble is a bird that makes different pitches out of it's whistling. In this passage, you get a feel of pastoral nature because in the last sentence "his mouth full of harmony and his soul full of gratitude" which displays the romanticized description that is being given.