No More Learning

Now when the categories
are to be applied to these ideas, it is not possible to give them
any object in intuition; but that such an object actually exists,
and           that the category as a mere form of thought is here
not empty but has significance, this is sufficiently assured them by
an object which practical reason presents beyond doubt in the
concept of the summum bonum, the reality of the conceptions which
are required for the possibility of the summum bonum; without,
however, effecting by this accession the least extension of our
knowledge on theoretical principles.