The current deployment of the concept of affect suffers from a disjunction between its potential utility and the promise projected on it by contemporary theorists. Specifically, the power of the vocabulary inspired by Gilles Deleuze and Félix Guattari's interventions of the 1970s—and stemming from Deleuze's earlier engagements with the philosophy of Baruch Spinoza—implicitly and at times explicitly invokes the promise that a critical perspective focused on affect can avoid the pitfalls of individual subjectivity and symbolic mediation in elucidating a dimension of relations between persons or beings that is direct or immediate. A coherent understanding of the concept of affect, however, demonstrates that its dimension is properly defined by the thorough interpenetration of bodies and mediation and, perhaps most strikingly, by how the limits imposed by subjectivity's horizon of opacity in turn affect the subject in corporeal ways. To the extent that theories of affect have hoped for new ethical possibilities to emerge from a thinking oriented toward the affective dimension, those theories must grapple with the paradoxes of mediation that already bedeviled the attempts early modern thinkers like David Hume and Adam Smith to understand how feelings are transferred from one individual to another. What these debates intuited was how ethical questions are, by their very nature, inextricably bound to the subject's blindness as to the desires and intentions of others and, ultimately, to important aspects of his or her own as well. While the transmission of affect is both real and a profoundly important quality of communication, the question the human being faces of what I ought to do not only cannot be relieved by such communications, it rebounds mercilessly on the affects and remains a relentless engine of our affective lives.