This dissertation argues that eighteenth-century literature is shaped by the modern encounter with-and transformation of-enthusiasm. By examining the rhetorical paradigms of invocation in the eighteenth century, this approach redefines the relationship of secularization to literary history and casts new light on the assumption that the Enlightenment represents a straightforward movement toward secularization. Literary critics have long agreed that the political and religious turmoil of the seventeenth century set the stage for widespread critiques of enthusiasm in the early eighteenth century. But early eighteenth-century literature did not simply reject enthusiastic expression; rather, this period saw a secularization of enthusiasm-a change that arose as a need to preserve inspiration's instrumental relationship to artistic production. The inception of this secularization is linked to the rise of aesthetic philosophy and to modernity's shifting relationship to the public sphere. The anxieties about enthusiasm in the Restoration period cause Augustan authors to reconsider the role of inspiration in modern writing and to reform enthusiasm through innovations in genre. These evocations of inspiration both exhibit an aestheticization of a theological category and import the affective fervor of an ancient theological practice into their modern redactions. This dissertation examines rhetorical paradigms of invocation in the works of Milton, Shaftesbury, Pope, and Fielding. These writers formally revise enthusiasm in a way that generates a new and distinctive representation of the author, in a process that relies on a rhetorical device that reformulates the passive structure of ancient invocation by subjecting it to the more dialogical methods of modern apostrophe and address. Incorporating invocation into their experiments in genre, these authors allow the figure of the muse to survive, but she is now construed as something secular, an apostrophe to a friend or judging spectator, or at times an allusion to the mental or aesthetic faculties of the author himself-his genius. This dissertation, therefore, argues that secularization impacts literary form long before the Romantic period and that secularization, in its relationship to aesthetic form and experience, is not merely an effect of Enlightenment rationality.