One of the big watersheds in American poetry of the last 100 years : the shift in the late 50s, by several major poets, from traditional high style, to free verse and a more informal diction. Robert Lowell, Adrienne Rich, James Wright come to mind. Maybe this was a second wave, since in the early decades of that century there had been a kind of double movement - first, the rise of vers libre and imagism (spearheaded by Harriet Monroe and her Poetry magazine), and second, Eliot's and Pound's complicated and influential reaction (both with & against) that trend. In the 20th century several contradictory crosscurrents of style were set in motion, causing trouble for partisan critics of one stream or another, since the poets' models and aims were so various and distinct.
The liberation of poetry from traditional prosody allowed for a great influx of new subject-matter, expanded ranges of diction and vocabulary; it brought to the fore all kinds of "prose virtues" (directness, simplicity, precision, clarity, etc.). What it also did was give an advantage to poets whose strength lay in invention : I mean the ability to invent new and fantastic scenarios, plots, and impressions with wit, satire, humor, journalistic immediacy, or fanciful inversions of ordinary experience. This capability - to evoke clever imaginary scenes - went a long way to make up for a thinning-out of the more traditional music of poetry (sonority, resonance, rhythm, rhetorical ebb & flow).
When I look back at my own stylistic models, choices & directions taken over the last half-century or so, it strikes me that one common thread joining my early love for the NY School and Ashbery, with my later fascination with Mandelstam and the Acmeist poets - and tied in as well with my affection for some aspects of Hart Crane, Berryman, Pound - is a distaste for prosaic direct statements, testimonies and observations. Not so much in themselves - I'm in favor of directness and simplicity in prose and ordinary conversation! - but in poetry. There is something one-dimensional about talky, flat, prosaic poems, which almost always puts me off. Does this make me an elitist, an aesthete, a reactionary, a traditionalist? I don't think so (just read my poems). The prosy poets make a claim for commonality, for egalitarian engagement : but I find the stance proves in the end to be mostly parochial and narcissistic.
There's a strong current in American poetry which resists the prosaic by an ascetic paring-down, a further simplification, in the interest of sharp observation, pithy statement. I admire these poets. I think I do retain a streak of midwestern reserve and understatement, which comes out in at least some of my writing. I like much in this vein, but I think it's not for me. I'm too interested in the resonance which comes from multiple layers of meaning, allegory, allusion; I'm too taken with the musicality of obscure images, their emotional freight.