If all C is D, then all A is B.
But, all C is D.
Therefore, all A is B.
Explain the difference between (1) the unity of the understanding which allows the concept A to be brought under the concept B and (2) the unity of reason which allows the judgment All A is B to be explained by the principle, If all C is D, then all A is B. In particular: explain how both (1) and (2) involve the unification of the same manifold of possible cognitions, namely, those falling under the concept A. The purpose of the unification (1) is to “collect much possible knowledge into one” — that is, in this case, to allow the predicate concept, B, to be applied at once to every object of the subject concept, A. So the possible objects of A are to be united in virtue of their common conformity to the concept A, and for the purpose of representing them all together as object to B. In virtue of what, and for what purpose, are the objects of A to be united in (2)?