 We are now ready to discuss the book itself. Murphy 1992 suggests that the first part of the book (the Introduction and Chapters 1 and 2) constitutes Deleuze’s treatment of the history of philosophy, while in the second part of the book (Chapters 4 and 5) Deleuze is doing philosophy in his own name. From this point of view, Chapter 3, on the “image of thought,” plays a pivotal role, leading us into Deleuze’s own philosophy. This transitional role of Chapter 3 is confirmed elsewhere when Deleuze says that the study of the image of thought is the “prolegomena to philosophy” (Negotiations, 149).