then it would overstep its bounds and pretend to be acquainted with
something of which it knows nothing. The conception of a world of
the understanding is then only a point of view which reason finds
itself compelled to take outside the appearances in order to
conceive itself as practical, which would not be possible if the
influences of the sensibility had a determining power on man, but
which is necessary unless he is to be denied the consciousness of
himself as an intelligence and, consequently, as a rational cause,
energizing by reason, that is, operating freely. This thought
certainly involves the idea of an order and a system of laws different
from that of the mechanism of nature which belongs to the sensible
world; and it makes the conception of an intelligible world
necessary (that is to say, the whole system of rational beings as
things in themselves). But it does not in the least authorize us to
think of it further than as to its formal condition only, that is, the
universality of the maxims of the will as laws, and consequently the
autonomy of the latter, which alone is consistent with its freedom;
whereas, on the contrary, all laws that refer to a definite object
give heteronomy, which only belongs to laws of nature and can only
apply to the sensible world.

But reason would overstep all its bounds if it undertook to
explain how pure reason can be practical, which would be exactly the
same problem as to explain how freedom is possible.

For we can explain nothing but that which we can reduce to laws, the
object of which can be given in some possible experience. But
freedom is a mere idea, the objective reality of which can in no
wise be shown according to laws of nature, and consequently not in any
possible experience; and for this reason it can never be