The essence of a poem is its theme (what it is expressing) and style (how it is expressed). In a successful work, these are integrated to form a coherent whole (in a masterpiece, they are transcendent). Usually, I find the theme determines the style.

In the “A Rhebok!” sketch, for example, the theme—wonder (mine at the sight of a wild animal) and panic (the creature’s at the sight of a person)—necessitates an animated style: simple words and short lines that evoke (its) alarm and (my) delight.