Michelangelo said he could sense the figure in the uncut stone; his job was to chip away marble till it emerged. Inuit sculptors say the same thing. And that makes sense to me. Cadence is the medium, the raw stone; the poem is already sustained in it. And writing means cutting away everything that isn't the poem. You can't "write" a poem, in fact - you can only help it stand free in the torrent. Most of my time with a pen is spent giving words, images, bright ideas that are borne along in cadence their permission to stay off the page. The poem is what remains; it is local cadence minus whatever is extraneous to its shapely articulation.
A bad poem, on the other hand, is something a poet made up.