"Brown and Dilke walked with me and back from the Christmas pantomime. I had not a dispute but a disquisition with Dilke on various subjects; several things dovetailed in my mind, and at once it struck me, what quality went to form a Man of Achievement, especially in Literature and which Shakespeare possessed so enormously -- I mean Negative Capability, that is when man is capable of being in uncertainties, Mysteries, doubts, without any irritable reaching after fact and reason. Coleridge, for instance, would let go by a fine isolated verisimilitude caught from the Penetralium of mystery, from being incapable of remaining content with half knowledge. This pursued through Volumes would perhaps take us no further than this, that with a great poet the sense of Beauty overcomes every other consideration, or rather obliterates all consideration."
-- John Keats: Letter to George and Tom Keats, 22 December 1818.
Keats applied this quality to people who write, but this Negative Capability could apply as well to people who read -- especially to people who read poems. After all, a poem could mean one thing to you at twenty, and something subtly different at fifty. Which meaning would be correct: the first? the second? neither? both? Sometimes we have no idea, and we have to accept the poem without a firm understanding of what it means -- if it means anything at all, beyond its goosebump effect on some hidden sector of the brain.
Uncertainties, mysteries, doubts -- these are what we have to expect, if we want to enjoy poetry. But how many of us would rather not read it?