The mind is an allegorical place. As it receives countless sense impressions from the body's nerves and the external world, the mind turns its impressions into ideas and then attempts to organize this perpetual stream of thoughts. This, at least, is the basic philosophical account of mind and body which runs through Descartes's groundbreaking work in Optics and Locke's theory of psychology from An Essay Concerning Human Understanding. Descartes and Locke agree that the mind's perception of external reality cannot always be trusted. Locke's famous chapter on the association of ideas, a late addition to the Essay's initially optimistic account of perception and cognition, anxiously shows how the mind joins together and confuses all sorts of images and ideas which should be kept distinct. Locke's ambivalent account of cognition—that the mind should give us a clear and distinct picture of reality even while it deceives us—held a firm grip on the eighteenth-century imagination. Locke's theory of association demonstrates the need for allegory. Allegory asks its readers to find an organizing principle of coherence within a host of images and figures. Yet Locke and his eighteenth-century disciples condemned allegory because its ever-changing metaphorical imagery can work against the mind's production of clear and distinct ideas.For eighteenth-century writers, Locke's comparison of allegory to the association of ideas would become a settled but unsettling truth. My dissertation argues that the Renaissance mode of allegory, a dynamic system of imagery which at once obscures its meaning and points toward some external or spiritual reality, carries on into the Enlightenment. Even if eighteenth-century fictions appear to prize the probable and the sensible over the spiritual, this secular description of fiction obscures the theological themes of many eighteenth-century works. My dissertation ultimately recovers the hidden remains of allegorical structure and narrative in eighteenth-century works from Bunyan's prose allegories to Richardson's Clarissa. In these writers' works, the mind or soul is an allegory-making factory which produces pictures or stories which help us make sense of the world.