We shall have to resign ourselves to this: that literature offers no signs, has never offered any signs, by which it can immediately be identified. The best, if not the only, test that we can apply is that suggested by Housman: check if a sequence of words, silently pronounced as the razor glides across our skin of a morning, sets the hairs of the beard on end, while a "shiver" goes "down the spine." . . . . As for Baudelaire, he was proud that Hugo had sensed, on reading his verses, a "new shiver." How else could we recognize peotry--and its departure from what came before? Something happens, something Coomaraswamy defined as "the aesthetic shock." Whether prompted by the apparition of a god or a sequence of words, the nature of that shock doesn't change. And this is what poetry does: it makes us see what otherwise we wouldn't have seen, through a sound that was never heard before."
--Robert Calasso, "Absolute Literature," in Literature and the Gods