This book's basic argument is that the Freudian unconscious, far from constituting a radical break with the philosophy of consciousness, is merely the latest exemplar in a heritage of philosophical misunderstanding of the Cartesian Cogito that interprets "I think, therefore I am" as "I represent myself, therefore I am" (in the classic interpretation of Heidegger, one of the targets of this book). According to the author, the certainty of the Cogito cannot be of a representational structure because it is precisely the notion of representation that is bracketed in Cartesian doubt. The certainty of the Cogito is more an "I feel" (an auto-affection), which on principle eludes the ek-stasis of representation in its modern sense. In such representation, subjectivity is always posed outside the self, whereas affectivity is felt in itself, immanently, without the mediation of any representation. In this sense, affectivity remains profoundly inaccessible to representation - not because it could only ever manifest itself as a representation, but because it manifests itself otherwise, in a manner anterior to the shown/hidden opposition that characterizes representational ek-stasis. The book traces this heritage from Descartes through Malebranche, Leibniz, Kant, and Schopenhauer to Freud. It also discusses Nietzsche, who the author argues stands outside this genealogy. In terms of contemporary theory, it presents a new analysis of the link between being and representation that has been central to French and American theory for the last two decades. For psychoanalysis, it provides fuel for those who are trying to go beyond both Freudian and Lacanian analysis to develop a psychoanalytic approach based on affect.