The “successive apprehension” would then be the pure numbering on the part of the number itself, which certainly does not take place over time. And therefore all the more fundamentally does the successive apprehension require time, since time always provides, a priori, the very entity that can be counted.137
The Kantian explanation of number as a schema remains incomplete and lacking in clarity, but one thing is clear: An ur-temporal determination of time—in this case, the ur-temporal production of time—does not understand time as time that is itself measured.
Pure number numbers-an-amount—it “numbers-an-amount” along with other numbers, which do the same thing. This pure numbering that number is, is in itself a highlighting of the now. Time is embedded in number as such; this pure numbering that number itself is, is a rule for counting off the countable. Number is a condition of the possibility for the countability of something, i.e., for the fact that entities can be quantitatively determined. That is, number—the schema, the ur-temporal time-determination that we have characterized—is the condition of the possibility for the fact that the pure category of quantity can be related to appearances, i.e., that there can be something like the measurability138 of objects, or objective measuring in general. Along with that, there pertains to the schema of quantity the constitution of the countability of whatever encounters through time. Time provides to the pure concept of the understanding a possible relation to objects. Numerus est quantitas phaenomenon, sc., per speciem temporis: Number is quantity as it shows itself in the image of time. It  is the concept of the understanding that shows up in this way and sensibilizes itself in this way. Or, to express the same thing from the standpoint of what shows up as a concrete thing, i.e., from the standpoint of the appearances: Number is the condition of the possibility of a determinability of the given by way of an a priori concept—in this case, the concept of quantity.
§33. Sensation as the schema of reality
The second schema, which Kant interprets with a certain thoroughness, is the schema of reality. (“Reality” is the first category within the second set of categories, which Kant designates as “quality.” With that, we see the direct connection of these concepts and the source of Hegel’s way of expressing himself, where reality and quality and existence are equally united.)
137. [Moser (p. 776.27–28) has “Sich-zählen-könnende,” instead of GA 21’s “das sich zählende Seiende.”]
138. [Moser (p.776.21) has Meßbarkeit instead of Messung.]