surfaces; they have an extension, which the sides of a geometric triangle, according to its concept, does not. The schema of this concept “triangle” is the presentation of the thinkable procedure for the intuitive depiction of the pure form [“triangle”] in the space of our lived world. The procedure—or, the rule of the procedure—is dictated by the concept. In a certain way the concept dictates a specific mode of its own sensibilization and thus its own “entry,” as it were, into the space of the lived world, so that it is thereby illustrated in what is depicted in the depiction that produces it. 
d) Image and schema
In the fourth place we mentioned (and this is the real problem) the sensibilization of the pure concepts of the understanding: the sensibilization of the categories. This is not just any schema. It is, as Kant says, the transcendental schema. In order to get any further, we need a much sharper understanding of the difference between an image and a schema than we’ve had heretofore, and we need to nail down the notion of image that Kant has been simply using from the beginning, but that can be properly understood only by first analyzing the phenomenon of image-as-copy. We will carry out our analysis of the difference between an image (now understood in a new way) and a schema by using Kant’s example of “an image of the number five” (B 179–180).
This image of the number five, which Kant adduces as five dots (• • • • •), must be distinguished from the schema of number. The reason we chose this specific example of the image of the number five in contrast to the schema of number is that later on, when we properly discuss the transcendental schematism, the question of number will surface again. However, scholars have not paid much attention to this distinction, if they go into it at all. The image of a number is one thing, and the schema of number is another. Most importantly, number as a schema is something entirely different from the previous two. Therefore, before we explain the kind of sensibilization that we put in the fourth place—indeed, in preparation for that—we shall discuss
1. “image” [Bild] as distinct from image-as-a-copy [Abbild];
2. “image” (in the new sense of no. 1) in its connection with “schema”;
3. the way schematization is enacted, and the faculty of this enactment;
4. and finally, the notion of a rule that governs this enactment of schematization.