inquiry into the powers of reason in regard to pure a priori
cognition； and is termed critical philosophy； or it is； secondly；
the system of pure reason… a science containing the systematic
presentation of the whole body of philosophical knowledge； true as
well as illusory； given by pure reason… and is called metaphysic。 This
name may； however； be also given to the whole system of pure
philosophy； critical philosophy included； and may designate the
investigation into the sources or possibility of a priori cognition；
as well as the presentation of the a priori cognitions which form a
system of pure philosophy… excluding； at the same time； all
empirical and mathematical elements。
Metaphysic is divided into that of the speculative and that of the
practical use of pure reason； and is； accordingly； either the
metaphysic of nature； or the metaphysic of ethics。 The former contains
all the pure rational principles… based upon conceptions alone （and
thus excluding mathematics）… of all theoretical cognition； the latter；
the principles which determine and necessitate a priori all action。
Now moral philosophy alone contains a code of laws… for the regulation
of our actions… which are deduced from principles entirely a priori。
Hence the metaphysic of ethics is the only pure moral philosophy； as
it is not based upon anthropological or other empirical
considerations。 The metaphysic of speculative reason is what is
monly called metaphysic in the more limited sense。 But as pure
moral philosophy properly forms a part of this system of cognition； we
must allow it to retain the name of metaphysic； although it is not
requisite that we should insist on so terming it in our present
discussion。
It is of the highest importance to separate those cognitions which
differ from others both in kind and in origin； and to take great
care that they are not confounded with those with which they are
generally found connected。 What the chemist does in the analysis of
substances； what the mathematician in pure mathematics； is； in a still
higher degree； the duty of the philosopher； that the value of each
different kind of cognition； and the part it takes in the operations
of the mind； may be clearly defined。 Human reason has never wanted a
metaphysic of some kind； since it attained the power of thought； or
rather of reflection； but it has never been able to keep this sphere
of thought and cognition pure from all admixture of foreign
elements。 The idea of a science of this kind is as old as
speculation itself； and what mind does not speculate… either in the
scholastic or in the popular fashion？ At the same time； it must be
admitted that even thinkers by profession have been unable clearly
to explain the distinction between the two elements of our
cognition… the one pletely a priori； the other a posteriori； and
hence the proper definition of a peculiar kind of cognition； and
with it the just idea of a science which has so long and so deeply
engaged the attention of the human mind； has never been established。
When it was said： 〃Metaphysic is the science of the first principles
of human cognition；〃 this definition did not signalize a peculiarity
in kind； but only a difference in degree； these first principles
were thus declared to be more general than others； but no criterion of
distinction from empirical principles was given。 Of these some are
more general； and therefore higher； than others； and… as we cannot
distinguish what is pletely a priori from that which is known to be
a posteriori… where shall we draw the line which is to separate the
higher and so…called first principles； from the lower and
subordinate principles of cognition？ What would be said if we were
asked to be satisfied with a division of the epochs of the world
into the earlier centuries and those following them？ 〃Does the
fifth； or the tenth century belong to the earlier centuries？〃 it would
be asked。 In the same way I ask： Does the conception of extension
belong to metaphysics？ You answer； 〃Yes。〃 Well； that of body too？
〃Yes。〃 And that of a fluid body？ You stop； you are unprepared to admit
this； for if you do； everything will belong to metaphysics。 From
this it is evident that the mere degree of subordination… of the
particular to the general… cannot determine the limits of a science；
and that； in the present case； we must expect to find a difference
in the conceptions of metaphysics both in kind and in origin。 The
fundamental idea of metaphysics was obscured on another side by the
fact that this kind of a priori cognition showed a certain
similarity in character with the science of mathematics。 Both have the
property in mon of possessing an a priori origin； but； in the
one； our knowledge is based upon conceptions； in the other； on the
construction of conceptions。 Thus a decided dissimilarity between
philosophical and mathematical cognition es out… a dissimilarity
which was always felt； but which could not be made distinct for want
of an insight into the criteria of the difference。 And thus it
happened that； as philosophers themselves failed in the proper
development of the idea of their science； the elaboration of the
science could not proceed with a definite aim； or under trustworthy
guidance。 Thus； too； philosophers； ignorant of the path they ought
to pursue and always disputing with each other regarding the
discoveries which each asserted he had made； brought their science
into disrepute with the rest of the world； and finally； even among
themselves。
All pure a priori cognition forms； therefore； in view of the
peculiar faculty which originates it； a peculiar and distinct unity；
and metaphysic is the term applied to the philosophy which attempts to
represent that cognition in this systematic unity。 The speculative
part of metaphysic； which has especially appropriated this
appellation… that which we have called the metaphysic of nature… and
which considers everything； as it is （not as it ought to be）； by means
of a priori conceptions； is divided in the following manner。
Metaphysic； in the more limited acceptation of the term； consists of
two parts… transcendental philosophy and the physiology of pure
reason。 The former presents the system of all the conceptions and
principles belonging to the understanding and the reason； and which
relate to objects in general； but not to any particular given
objects （Ontologia）； the latter has nature for its subject…matter；
that is； the sum of given objects… whether given to the senses； or； if
we will； to some other kind of intuition… and is accordingly
physiology； although only rationalis。 But the use of the faculty of
reason in this rational mode of regarding nature is either physical or
hyperphysical； or； more properly speaking； immanent or transcendent。
The former relates to nature； in so far as our knowledge regarding
it may be applied in experience （in concreto）； the latter to that
connection of the objects of experience； which transcends all
experience。 Transcendent physiology has； again； an internal and an
external connection with its object； both； however； transcending
possible experience； the former is the physiology of nature as a
whole； or transcendental cognition of the world； the latter of the
connection of the whole of nature with a being above nature； or
transcendental cognition of God。
Immanent physiology； on the contrary； considers nature as the sum of
all sensuous objects； consequently； as it is presented to us… but
still according to a priori conditions； for it is under these alone
that nature can be presented to our minds at all。 The objects of
immanent physiology are of two kinds： 1。 Those of the external senses；
or corporeal nature； 2。 The object of the internal sense； the soul；
or； in accordance with our fundamental conceptions of it； thinking
nature。 The metaphysics of corporeal nature is called physics； but； as
it must contain only the principles of an a priori cognition of
nature； we must term it rational physics。 The metaphysics of
thinking nature is called psychology； and for the same reason is to be
regarded as merely the rational cognition of the soul。
Thus the whole system of metaphysics consists of four principal
parts： 1。 Ontology； 2。 Rational Physiology； 3。 Rational cosmology； and
4。 Rational theology。 The second part… that of the rational doctrine
of nature… may be subdivided into two； physica rationalis* and
psychologia rationalis。
*It must not be supposed that I mean by this appellation what is
generally called physica general is； and which is rather mathematics
than a philosophy of nature。 For the metaphysic of nature is
pletely different from mathematics； nor is it so rich in results；
although it is of great importance as a critical test of the
application of pure understanding…cognition to nature。 For want of its
guidance； even mathematicians； adopting certain mon notions…
which are； in fact； metaphysical… have unconsciously crowded their
theories of nature with hypotheses； the fallacy of which bees
evident upon the application of the principles of this metaphysic；
without detriment； however； to the employment of mathematics in this
sphere of cognition。
The fundamental idea