Now, in nature, as it actually is an object of experience, the free
will is not of itself determined to maxims which could of themselves
be the foundation of a natural system of universal laws, or which
could even be adapted to a system so constituted; on the contrary, its
maxims are private inclinations which constitute, indeed, a natural
whole in conformity with pathological (physical) laws, but could not
form part of a system of nature, which would only be possible
through our will acting in accordance with pure practical laws. Yet we
are, through reason, conscious of a law to which all our maxims are
subject, as though a natural order must be originated from our will.
This law, therefore, must be the idea of a natural system not given in
experience, and yet possible through freedom; a system, therefore,
which is supersensible, and to which we give objective reality, at
least in a practical point of view, since we look on it as an object
of our will as pure rational beings.

Hence the distinction between the laws of a natural system to
which the will is subject, and of a natural system which is subject to
a will (as far as its relation to its free actions is concerned),
rests on this, that in the former the objects must be causes of the
ideas which determine the will; whereas in the latter the will is
the cause of the objects; so that its causality has its determining
principle solely in the pure faculty of reason, which may therefore be
called a pure practical reason.

There are therefore two very distinct problems: how, on the one
side, pure reason can cognise objects a priori, and how on the other
side it can be an immediate determining principle of the will, that
is, of the causality of the rational being with respect to the reality
of objects (through the mere thought of the universal validity of