action; it must therefore hold for all rational beings (to whom an
imperative can apply at all), and for this reason only be also a law
for all human wills. On the contrary, whatever is deduced from the
particular natural characteristics of humanity, from certain
feelings and propensions, nay, even, if possible, from any
particular tendency proper to human reason, and which need not
necessarily hold for the will of every rational being; this may indeed
supply us with a maxim, but not with a law; with a subjective
principle on which we may have a propension and inclination to act,
but not with an objective principle on which we should be enjoined
to act, even though all our propensions, inclinations, and natural
dispositions were opposed to it. In fact, the sublimity and
intrinsic dignity of the command in duty are so much the more evident,
the less the subjective impulses favour it and the more they oppose
it, without being able in the slightest degree to weaken the
obligation of the law or to diminish its validity.

Here then we see philosophy brought to a critical position, since it
has to be firmly fixed, notwithstanding that it has nothing to support
it in heaven or earth. Here it must show its purity as absolute
director of its own laws, not the herald of those which are
whispered to it by an implanted sense or who knows what tutelary
nature. Although these may be better than nothing, yet they can
never afford principles dictated by reason, which must have their
source wholly a priori and thence their commanding authority,
expecting everything from the supremacy of the law and the due respect
for it, nothing from inclination, or else condemning the man to
self-contempt and inward abhorrence.

Thus every empirical element is not only quite incapable of being an