determining principle of the choice must be empirical and,
therefore, also the practical material principle which presupposes
it as a condition.

In the second place, since susceptibility to a pleasure or pain
can be known only empirically and cannot hold in the same degree for
all rational beings, a principle which is based on this subjective
condition may serve indeed as a maxim for the subject which
possesses this susceptibility, but not as a law even to him (because
it is wanting in objective necessity, which must be recognized a
priori); it follows, therefore, that such a principle can never
furnish a practical law.



{BOOK_1|CHAPTER_1 ^paragraph 20}

III. THEOREM II.



All material practical principles as such are of one and the same
kind and come under the general principle of self-love or private
happiness.

Pleasure arising from the idea of the idea of the existence of a
thing, in so far as it is to determine the desire of this thing, is
founded on the susceptibility of the subject, since it depends on
the presence of an object; hence it belongs to sense (feeling), and
not to understanding, which expresses a relation of the idea to an