reason. This reason, however, went so far as to establish with
certainty the concept of noumena; that is, the possibility, nay, the
necessity, of thinking them; for example, it showed against all
objections that the supposition of freedom, negatively considered, was
quite consistent with those principles and limitations of pure
theoretic reason. But it could not give us any definite enlargement of
our knowledge with respect to such objects, but, on the contrary,
cut off all view of them altogether.

On the other hand, the moral law, although it gives no view, yet
gives us a fact absolutely inexplicable from any data of the
sensible world, and the whole compass of our theoretical use of
reason, a fact which points to a pure world of the understanding, nay,
even defines it positively and enables us to know something of it,
namely, a law.

{BOOK_1|CHAPTER_1 ^paragraph 130}

This law (as far as rational beings are concerned) gives to the
world of sense, which is a sensible system of nature, the form of a
world of the understanding, that is, of a supersensible system of
nature, without interfering with its mechanism. Now, a system of
nature, in the most general sense, is the existence of things under
laws. The sensible nature of rational beings in general is their
existence under laws empirically conditioned, which, from the point of
view of reason, is heteronomy. The supersensible nature of the same
beings, on the other hand, is their existence according to laws
which are independent of every empirical condition and, therefore,
belong to the autonomy of pure reason. And, since the laws by which
the existence of things depends on cognition are practical,