This book by R.A. York mentioned earlier here (Poem as Utterance), surveys various 20th-cent poets - evaluates the discourse, the communicative gesture, in their poems, in terms of what shared assumptions or shared experience or knowledge - shared with the reader - it reflects.
Looking at poems for what is left unstated, what can remain implicit, or what can be included "informally", conversationally, because it's assumed to be general knowledge, shared experience. How the conveyance of shared experience builds confidence or a sense of authority granted.
Frost wrote somewhere that good poems don't instruct the reader about what they don't know; they express gracefully what the reader knows already.
Are poems a kind of discourse production - or can they be rather a relief, a vacation, a rescue from same? Since the achievement of a communicative poiesis (perhaps a kind of conjunction of opposites) allows so much effort & expostulation and explanation to drop away?