When the Dreamer of Pearl first encounters the Maiden, he attempts to describe a giant pearl affixed to her bosom and finds he can only say, “A manneʒ dom moʒt dryʒly demme / Er mynde moʒt malte in hit mesure. / I hope no tong moʒt endure / No sauerly saghe say of þat syʒt.” Just when he hopes to be able to say something about the Maiden, the Dreamer's language fails him and he has to give an approximation of what he sees. In my dissertation, I explore the outcomes of such failures of language in visionary writing. Instead of dwindling into silence in the face of the ineffable, as one might expect, English visionary writing exploits language’s fecundity. Past work on visionary literature separates so-called mystic visions from what are supposed to be their more poetic counterparts, identifying mystic visions as primarily religious texts and poetic dream visions as primarily literary texts. I argue instead that mystic, what I call “waking,” visions and dream visions are inextricably linked through the way they engage the reader in the work of the vision. I identify waking and dream visions as a part of visionary literature, a body of writing that questions the sufficiency of language even as it reaches out to the reader to recuperate some of language’s failures.