After Pope, in the beginning of Romanticism, people developed the idea that imagination rather than reason was a special form of knowledge and its best expression is through poetry. Therefore, poetry should not try to do the stuff that mere prose does: convey information or make arguments about ideas.
Robert Hass[Osip] Mandelstam, who wasn't a political thinker, loved the idea of the city-state. One of the emblems in his poetry of the politics he imagined, over and against the universalizing politics of [Carl] Marx, was the medieval city of Novgorod, which had in its center a public well where the water was free to everyone. That became for him a figure of justice.
Robert HassWhen I applied to Stanford, I applied for graduate work in the PhD program, not to the creative writing program, mostly because though I had some vague ambition of becoming a writer and I was trying to write poems and essays and stories, I didn't feel like I was far enough along to submit work to some place and have it judged.
Robert HassI am talking about poetry. It's like that line from [John] Yeats: I go back to "where all the ladders start/ In the foul rag and bone shop of the heart."
Robert Hass