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 pass 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。
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；
supersensible nature； so far as we can form any notion of it； is
nothing else than a system of nature under the autonomy of pure
practical reason。 Now； the law of this autonomy is the moral law；
which； therefore； is the fundamental law of a supersensible nature；
and of a pure world of understanding； whose counterpart must exist
in the world of sense； but without interfering with its laws。 We might
call the former the archetypal world （natura archetypa）； which we only
know in the reason； and the latter the ectypal world （natura
ectypa）； because it contains the possible effect of the idea of the
former which is the determining principle of the will。 For the moral
law； in fact； transfers us ideally into a system in which pure reason；
if it were acpanied with adequate physical power； would produce the
summum bonum； and it determines our will to give the sensible world
the form of a system of rational beings。
The least attention to oneself proves that this idea really serves
as the model for the determinations of our will。
When the maxim which I am disposed to follow in giving testimony
is tested by the practical reason； I always consider what it would
be if it were to hold as a universal law of nature。 It is manifest
that in this view it would oblige everyone to speak the truth。 For
it cannot hold as a universal law of nature that statements should
be allowed to have the force of proof and yet to be purposely
untrue。 Similarly； the maxim which I adopt with respect to disposing
freely of my life is at once determined； when I ask myself what it
should be； in order that a system； of which it is the law； should
maintain itself。 It is obvious that in such a system no one could
arbitrarily put an end to his own life； for such an arrangement
would not be a permanent order of things。 And so in all similar cases。
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
its own maxims as laws）。
The former； which belongs to the critique of the pure speculative
reason； requires a previous explanation； how intuitions without
which no object can be given； and； therefore； none known
synthetically； are possible a priori； and its solution turns out to be
that these are all only sensible and； therefore； do not render
possible any speculative knowledge which goes further than possible
experience reaches； and that therefore all the principles of that pure
speculative reason avail only to make experience possible； either
experience of given objects or of those that may be given ad
infinitum； but never are pletely given。
The latter； which belongs to the critique of practical reason；
requires no explanation how the objects of the faculty of desire are
possible； for that being a problem of the theoretical knowledge of
nature is left to the critique of the speculative reason； but only how
reason can determine the maxims of the will； whether this takes
place only by means of empirical ideas as principles of determination；
or whether pure reason can be practical and be the law of a possible
order of nature； which is not empirically knowable。 The possibility of
such a supersensible system of nature； the conception of which can
also be the ground of its reality through our own free will； does
not require any a priori intuition （of an intelligible world） which；
being in this case supersensible； would be impossible for us。 For
the question is only as to the determining principle of volition in
its maxims； namely； whether it is empirical； or is a conception of the
pure reason （having the legal character belonging to it in general）；
and how it can be the latter。 It is left to the theoretic principles
of reason to decide whether the causality of the will suffices for the
realization of the objects or not； this being an inquiry into the
possibility of the objects of the volition。 Intuition of these objects
is therefore of no importance to the practical problem。 We are here
concerned only with the determination of the will and the
determining principles of its maxims as a free will； not at all with
the result。 For； provided only that the will conforms to the law of
pure reason； then let its power in execution be what it may； whether
according to these maxims of legislation of a possible system of
nature any such system really results or not； this is no concern of
the critique； which only inquires whether； and in what way； pure
reason can be practical； that is directly determine the will。
In this inquiry criticism may and must begin with pure practical
laws and their reality。 But instead of intuition it takes as their
foundation the conception of their existence in the intelligible
world； namely； the concept of freedom。 For this concept has no other
meaning； and these laws are only possible in relation to freedom of
the will； but freedom being supposed； they are necessary； or
conversely freedom is necessary because those laws are necessary；
being practical postulates。 It cannot be further explained how this
consciousness of the moral law； or； what is the same thing； of
freedom； is possible； but that it is admissible is well established in
the theoretical critique。
The exposition of the supreme principle of practical reason is now
finished； that is to say； it has been… shown firs