I’ve just read, and herewith recommend, this interview by McSweeny’s of the poet Rebecca Lindenberg. Asked, “why write poetry?” she answers:
I think there is a general misconception that you write poems because you “have something to say.” I think, actually, that you write poems because you have something echoing around in the bone-dome of your skull that you cannot say. Poetry allows us to hold many related tangential notions in very close orbit around each other at the same time. The “unsayable” thing at the center of the poem becomes visible to the poet and reader in the same way that dark matter becomes visible to the astrophysicist. You can’t see it, but by measure of its effect on the visible, it can become so precise a silhouette you can almost know it.