There's something so important in Eliot's notion of "dissociation of sensibility". I'm not exactly sure what it is, yet. The way someone places a historical marker for where it supposedly begins, is basic cultural myth-making, like the Serbian concept of the Field of the Raven.

Eliot puts it after the "metaphysicals" - and links it to a loss of the medieval synthesis. But the medieval synthesis was mythological. He should read Cusanus : a renascent-metaphysic to beat the nostalgia of metaphysical poetry (Donne's elegy for that synthesis basically scripted Eliot's notion). Cusanus "enfolded" the dualities of what was to come (reality/imagination, faith/scepticism, superstition/science, philosophy/praxis) in a creative intellectual synthesis which bears comparison to Leonardo da Vinci's in the realm of art/science.

I would put the "dissociation" much later. Keats & Milton represent still (& marvelously) synthetic unities of reason/imagination. Their poetry combines feeling and argument, image & discourse.

With the progress of science, Enlightenment, humanism, journalism, telecommunications. . . poetry was forced into a corner marked by indirection. American poetry offers the same picture in colonial miniature : a progress of deflection (Keats to imagism = Whitman to imagism).

The history of poetry in English since 1800 (after the Romantic-Sentimental revolt against Augustan-Enlightenment uber-rationalism) is a progress of deflection - away from the union of logic & song (thus we have Black Dog Songs, as I described them the other day).

Part of my fascination with Language Poetry in the early 90s (when I became aware of it) was my sense that it represented a literary-historical terminus of this process.