The Introduction defines debt as a financial tool and as a theological concept, summarizing the role of debt in the late medieval English economy and in the sacrament of penance. This dual definition challenges the “separate spheres” interpretive paradigm that dominates literary history. A paradigm in which economics and theology are constitutive of two ideally separate modes, this dominant interpretive approach frames the shift from feudalism to capitalism as a shift from the traditional bonds of hierarchy and communalism to modern individualism and competitive acquisition. Understanding capitalism as an economy of debt makes possible a new perspective on economic change in late medieval England, one that revises Weber’s spirit of capitalism and challenges Weberian periodisation. The image of God as a bookkeeper and the concomitant understanding of sin as a debt that cannot be fully discharged is first elaborated and disseminated en masse in the late medieval flowering of vernacular literature in England and in Europe. This, I argue, is the cultural site where the systematization of the ethical conduct of life is imagined for the first time not only as a possibility for all people, but as a requirement.