One must have a mind of winter.
The greatest lines in poetry are infinitely quotable while having no definite meaning. What is a mind of winter, and why must one have one? It doesn’t matter. Wallace Stevens’ greatness lay in his ability to produce these kinds of anti-aphorisms, seemingly wise but ultimately ungraspable: Thought is false happiness. She sang beyond the genius of the sea. The only emperor is the emperor of ice cream. And, most pointedly: The poem must resist the intelligence / almost successfully. (Or, nay, successfully!)
I believe that to read poetry, one must have a mind of poetry. You must enter a state where you come to understand meaning-resistant arrangements of language as having their own kind of meaning. It’s quite similar to those Magic Eye posters from the ‘90s: If you haven’t figured out how to look at them, you can’t believe that anyone really sees the dolphin. (This metaphor has its limits, making learned skill seem like an on/off conversion; too, with poetry, even when you’ve mastered “the trick,” not everyone sees the same thing.)
Is this “negative capability”? I’m not sure. More… “Inside the Mind of Poetry”