of the understanding can relate to appearances—one proves the possibility of their objective validity.
The general condition of a possible applicability of a category to objects consists in the fact that the category as such and in general must contain in itself, a priori, something sensible. But this something-sensible, insofar as it is a priori necessary for the objectivity of the category, is at the same time that which restricts the applicability of the category to sensibility, to appearances in general. This condition—the something-sensible that a category must be able to have—is what Kant calls the schema of the categories, the schema of the pure concepts of the understanding.
To understand that, let us first ask: What does a “schema of a concept” mean in general? And even before that: What does “schema” mean? Kant distinguishes (although not always or in all respects rigorously) between “schema” and “image.” In this context, let us ask more concretely about the difference between the two, and about the difference between “image,” “depiction,” and “schema” (or “schematizing”). [360] As regards this present consideration and the earlier ones, let me say: I am lecturing not about Kant but about logic. And just as the earlier phenomenological interpretations of synthesis clarified the basic structures of the possibility of the judgment, so now, our explanation of the schematism will discuss phenomenologically the basic structures of the possibility of concepts in general.
But how can we bring together image and schema, depiction and schematizing, for the purpose of working out their differences? How do they differ from each other, and how do they belong together?
Image and schema are intuitables [Anschauliches] that can be produced in such a way that, as intuitable, they portray something they themselves are not. They let the thing be seen or understood in different ways according to the case: depictions in intuitables; and sensibilizations.114 Sensibilizations differ from acts of intuition [Anschauungen], and portrayals [Darstellendes] differ from intuitables [Auschaunbarem] insofar as the intuitable can be directly grasped, that is, it gets intuited only as itself. Grasping and understanding a depiction (i.e., what’s grasped: the portrayal or image of something) must necessarily, primarily, and thematically grasp, comprehend, and (in the broadest sense) understand what is getting depicted.
We said, “to be seen or to be understood.” We made this distinction with a view to whether the depiction itself is sensibly intuitable or whether what is to be depicted qua sensibilized is, of its essence, not sensibly intuitable. (Kant calls the latter case the sensibilization of concepts.) This distinction between the [sensible] portrayal of a [sensibly]
114. [That is, they make something be “related-to-the-sensible.”]