[be] -- prose
Poetry may be defined as “constrained writing”. It uses some sort of linguistic device to order words and phrases. Poetry tends towards repetitive structures (e.g. the fixed rhythms of Greek and Latin), but it does not always employ them (e.g. TS Eliot). The lack of repetition in free verse is compensated for by more subtle constraints in other areas.
Prose is everything that is not poetry. Its distinguishing feature is therefore the absence of poetic constraints.
Art is form. The thing that makes art art is not the words, musical notes, or colors that we perceive (for animals too perceive) but our uniquely human appreciation of their internal *organization*. Organization is achieved through constraints. Since prose lacks constraints, is it possible to create art in this medium?