The first day, for example, Whitman merely catalogs his encounter of a few small birds. His phrases are short, lacking adjectives, lacking explicit emotion. The next day, we encounter extreme verbiage, lengthy phrases, decorative descriptions, and allusory detail. The third day becomes less of a catalog an more of a personal encounter, where sensory language detailing and celebrating the physicality of existence is utilized.
Where this becomes interesting, of course, is when thinking of the length it took Whitman to write Leaves of Grass, and also his further edits made in later years. Essentially, it explains the divergent voices found throughout the text, what Whitman would perhaps describe by stating he is the voice of the people, an ever-changing field of growth. Some section are clearly physical, such as the romance where a lover is to reach into the very chest of the narrator. Some sections are self reflexive, It is probably that these varying sections, similar to his journal entries, focus on different avenues of existence due to when they were written. This both accounts and explains the Whitman-esque transforming voice, morphing like leaves from one day to the next.
"I know perfectly well my own egotism,
|And know my omniverous words, and cannot say any less,|
|And would fetch you whoever you are flush with myself."|