•Why it earns a slot
Why it earns a slot: it rewrote what American poetry could sound like by dropping meter and rhyme entirely and insisting the poem itself was a physical body the reader could touch.
A thirty-seven-year-old poet declares his own body and the reader's one substance, then spends hundreds of pages proving it by refusing to apologize for a single contradiction.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.