In the history of human culture, no organ or body part has been more closely identified with emotion than the heart. Cardiac Realism: The Affective Life of the Modern Novel illuminates a tradition of British novelists writing from the 1840s to the 1920s who turn to the heart to grapple with one of the perennial challenges of the novel form: how can prose fiction express the physical intensity of emotional experience? Whilst engaging with a wide range of writers, from Daniel Defoe to Ben Lerner, this volume strategically pairs two nineteenth century realists with the two early twentieth century modernists that they most profoundly influenced. Dissatisfied with the perceived neglect of bodily feeling in the novels of their predecessors and peers, Charlotte Brontë, Thomas Hardy, May Sinclair, and D. H. Lawrence develop heart-centred strategies of affective description that refocus attention from mentation to the somatic lineaments of emotion, expanding the remit of novelistic 'interiority' to encompass the visceral commotions of the bodily interior. This more corporeal narrative of the modern novel—developed in dialogue with the history of medicine, science, and emotion—rethinks realism and modernism as literary modes animated by a far wider array of philosophies of experience than has yet been recognized. The most wide-reaching ramification of Cardiac Realism is its argument that novel criticism needs to recalibrate its methods to register the real philosophical work performed by experiential description—the novel form's most subtle and sophisticated tool for theorizing what it is like to be a thinking, feeling human being, with a racing mind and beating heart.