This dissertation examines the interrelation of literary criticism and science of mind in the long eighteenth century by focusing on theories of imagination, fancy, and wit. In grounding these creative faculties in the physiology of the human brain, eighteenthcentury thinkers explained the fanciful juxtapositions of the imagination by drawing on experimental science, even as they stressed the confused and mutable nature of the corporeal mind. In so doing, writing on fancy, wit, and metaphor became a means of questioning the boundaries between the thinking subject and the seemingly thoughtless body, the conscious mind and the matter that subtends it. I track this history in the works of Thomas Hobbes, Thomas Willis, John Locke, Alexander Pope, Jonathan Swift, and Laurence Sterne.