The aim of this study is to identify the genesis of the concept of image of thought in two works belonging to Deleuze’s first philosophical phase: Nietzsche and Philosophy and Proust and the Signs. In our reading of these works, we show the central importance of this concept for the elaboration of Deleuzian thought. We also confirm the importance of the concept in relation to the evolution of Deleuze’s philosophy. In the first of these works, the image of thought is linked to the profound critical renewal of Nietzsche’s philosophy as claimed by Deleuze. In Proust and the Signs, we observe a deepening of this critical conception which is operated from beyond philosophy, i.e. non-philosophy, literature and, in particular, the Proustian oeuvre. It is thus a matter here of linking philosophy to non-philosophy, creating a creative interference between these two planes, and renewing our image of thought from this intercession.