I argue that, for Kant, there is a point at which the notions of self-consciousness and self-limitation become one. I proceed by spelling out a logical progression of forms of self-consciousness in Kant’s philosophy, where at each stage we locate the limits of the capacity in question and ask what it takes to know those limits. After briefly sketching a notion of self-consciousness available even to the animal, we look at whether there could be a notion of self-consciousness available to the capacity of human sensibility. At this stage I argue that Kant and Heidegger (or Heidegger’s Kant) share a conception of what it is to be self-limiting through self-consciousness. I then critically examine this conception, and, specifically, the way in which it fails to account for the most essential form of self-limitation in Kant’s critical philosophy—namely, the form of self-limitation which rejects spatial and temporal articulation. The conclusion we reach is that Kant’s theory of transcendental self-consciousness is a theory of the activity of thinking as determining itself (including its limits) non-spatially and non-temporally.