Strangeness.

I think that poetry at its greatest–in Dante, Shakespeare, Donne, Milton, Blake–has one broad and essential difficulty; it is the true mode for expanding our consciousness. This it accomplishes by what I have learned to call strangeness. Owen Barfield was one of several critics to bring forth strangeness as a poetic criterion. For him, as for Walter Pater before him, the Romantic added strangeness to beauty: Wallace Stevens, a part of this tradition, has a Paterian figure cry out: “And there I found myself more truly and more strange.  As Barfield intimates, consciousness is to poetry what marble is to sculpture: the material that is being worked. Words are figurations of consciousness: metaphorical of consciousness, the poet’s words invite us to share in a strangeness.

Harold Bloom, from The Best Poems in the English Language