… 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 a 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. (The Complete Poetical Works and Letters of John Keats, p. 277)
We hate poetry that has a palpable design upon us, and, if we do not agree, seems to put its hand into its breeches pocket. Poetry should be great and unobtrusive, a thing which enters into one's soul, and does not startle it or amaze it with itself but with its subject. How beautiful are the retired flowers! how would they lose their beauty were they to throng into the highway, crying out, Admire me, I am a violet! (The Complete Poetical Works and Letters of John Keats, p. 286)