In his wonderful book, State of the Art, David Lehman writes:
After observing that "every revolution in poetry" is at base "a return to common speech," T.S. Eliot in "The Music of Poetry" (1942) goes on to give the rationale for this sort of "talk poetry": "No poetry, of course, is ever exactly the same speech that the poet talks and hears" but it has to be in such a relation to the speech of his time that the listener or reader can say 'that is how I should talk if I could talk poetry.''