Excitable Imaginations reveals a durable and instrumental connection between aesthetics and sexuality in eighteenth-century British literature, specifically that theories of aesthetic experience are forged through erotic writing. Because images of sexuality invite unusually strong affective and visceral reactions, they provide authors with an evocative means for testing the fragile boundary between virtue and vice. In this site of experimentation, I argue, authors most clearly delineate how readers can use their imagination, a faculty celebrated in this period for its capacity to convert bodily pleasure into intellectual labor, to unite the prurient curiosities raised by literature with the moral instruction it so often promotes. As eroticism heightens imaginative excitability, authors from the Eliza Haywood to Edmund Burke call readers’ attention to their own bodily sensations so that they might celebrate the passions aroused by texts and yet resist lewd desires. “Reader, if thou art of an amorous Hue,” writes Henry Fielding in Joseph Andrews, “I advise thee to skip over the next Paragraph,” which contains the portrait of a young heroine “bursting through her tight Stays, especially in the Part which confined her swelling Breasts.” Rather than censor erotic images, Fielding and his contemporaries structure such descriptions to emphasize their mischievous content and the self-evaluation it occasions in readers. As I show chronologically in five chapters, the aesthetic acquires form as authors variously exploit sexuality for its unique potential to animate the imagination and to prompt inward reflection.