There is this book, Louis Zukovsky’s A Test of Poetry, which looks very interesting. Then there is this review by the same title, on American poet George Oppen. Here are some of the things it points out:
True poetry, says Oppen in an essay collected in Selected Prose, is written in “a language that tests itself.”
Generally, twentieth-century American poets recognized two strategies by which a poem might register a political effect: a poem might express a political position thematically or it might embody a position formally by disrupting aesthetic norms. Oppen rejected both these strategies as self-congratulatory, untestable: “We must cease to believe in secret names and unexpected phrases which will burst the world.” Without fanfare, he refused the notion that a poet could fulfill his social responsibilities by writing any kind of poem, and neither did this refusal engender any contempt for poetry.
I thought I had encountered
Permanence; thought leaped on us in that sea
For in that sea we breathe the open
Of place, and speak
If we would rescue
Love to the ice-lit
Upper World a substantial language
Of clarity, and of respect.
Oppen is thinking of Orpheus here, the poet who failed to rescue his love, the dead Eurydice, to the upper world. To test oneself, Oppen recognized, is to know failure. Oppen’s victories are no less great for being small.