The Levels of Poetry

If fiction is "the art of written narrative," and drama is "the art of theatrical narrative," both of these using language as a vehicle to tell a story, and the various nonfiction genres are "the art of rhetorical exposition," using language as a vehicle to make didactic or argumentative points, then what is poetry, since it can do, and originally did all of these things? Since poetry is the product of the poet who is interested in the vehicle itself, in language as the medium for expression, then poetry is "the art of language." Like the other genres (see The Book of Literary Terms), poetry also has four elements, but in this case they are levels of language usage, those of typography, sound, tropes ("figures of speech"), and theme. And there is fusion as well -- how do all these levels com together to make a poem?