To the three categories of quantity, reality, and substance there correspond three schemata. The schema of quantity is number, numerus. The schema of reality is sensation, sensatio. The schema of substantiality is perdurance, the perdurabile.
§32. Number as the schema of quantity
We should note that we have already dealt with number in our earlier discussions regarding schematism, and there the issue was a possible sensibilization—schematization—of number itself: it was a matter of discovering the schema for a number. But now, by way of contrast, it is a question of the sensibilization of the category “quantity,” whose pure image is number itself. Number is primarily nothing else but the pure image of quantity. As regards its conceptual character, this pure image of quantity is a pure sensible concept; and as a pure sensible concept, number in turn requires sensibilization, a new schematization. Kant did not provide any further discussion of these various schematisms—the schematism of quantity as number; the schematism of number itself is some kind of spatial form—nor did he show their inner connection.
The schema of quantity is number, numerus. That means: The synthesis speciosa temporis is regulated by “quantity” or “plurality,” and what it makes visible in the image is number. This first has to be explained in phenomenological terms, and to do that we have to come up with some answers:
• In what way does time underlie the synthesis speciosa in this schema, “number”?
• What kind of time-determination shows up there?
• And what does the “determination of time” mean in the schema • “number”?
Kant’s answer to all of this is: In the schema “number,” the determination of time is the production of time.
In the explanation that follows you must try to really see the things at stake. The rule for rendering visible the pure category of quantity in the image of time is number. This rule  itself is a transcendental determination of time with regard to plurality. The mode of carrying out this determination of time is the synthesis speciosa, which has the pure time-manifold in view and which, as a productive giving of the image (giving it from out of itself and to itself), has to render this timemanifold visible.
Rendering the pure time-manifold visible simply means highlighting the pure one-after-another, the now-sequence, that is, the nows them