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 of a philosophy of pure reason of necessity
dictates this division； it is； therefore； architectonical… in
accordance with the highest aims of reason； and not merely
technical； or according to certain accidentally…observed
similarities existing between the different parts of the whole
science。 For this reason； also； is the division immutable and of
legislative authority。 But the reader may observe in it a few points
to which he ought to demur； and which may weaken his conviction of its
truth and legitimacy。
In the first place； how can I desire an a priori cognition or
metaphysic of objects； in so far as they are given a posteriori？ and
how is it possible to cognize the nature of things according to a
priori principles； and to attain to a rational physiology？ The
answer is this。 We take from experience nothing more than is requisite
to present us with an object （in general） of the external or of the
internal sense； in the former case； by the mere conception of matter
（impenetrable and inanimate extension）； in the latter； by the
conception of a thinking being… given in the internal empirical
representation； I think。 As to the rest； we must not employ in our
metaphysic of these objects any empirical principles （which add to the
content of our conceptions by means of experience）； for the purpose of
forming by their help any judgements respecting these objects。
Secondly； what place shall we assign to empirical psychology；
which has always been considered a part of metaphysics； and from which
in our time such important philosophical results have been expected；
after the hope of constructing an a priori system of knowledge had
been abandoned？ I answer： It must be placed by the side of empirical
physics or physics proper； that is； must be regarded as forming a part
of applied philosophy； the a priori principles of which are
contained in pure philosophy； which is therefore connected； although
it must not be confounded； with psychology。 Empirical psychology
must therefore be banished from the sphere of metaphysics； and is
indeed excluded by the very idea of that science。 In conformity；
however； with scholastic usage； we must permit it to occupy a place in
metaphysics… but only as an appendix to it。 We adopt this course
from motives of economy； as psychology is not as yet full enough to
occupy our attention as an independent study； while it is； at the same
time； of too great importance to be entirely excluded or placed
where it has still less affinity than it has with the subject of
metaphysics。 It is a stranger who has been long a guest； and we make
it wele to stay； until it can take up a more suitable abode in a
plete system of anthropology… the pendant to empirical physics。
The above is the general idea of metaphysics； which； as more was
expected from it than could be looked for with justice； and as these
pleasant expectations were unfortunately never realized； fell into
general disrepute。 Our Critique must have fully convinced the reader
that； although metaphysics cannot form the foundation of religion；
it must always be one of its most important bulwarks； and that human
reason； which naturally pursues a dialectical course； cannot do
without this science； which checks its tendencies towards dialectic
and； by elevating reason to a scientific and clear self…knowledge；
prevents the ravages which a lawless speculative reason would
infallibly mit in the sphere of morals as well as in that of
religion。 We may be sure； therefore； whatever contempt may be thrown
upon metaphysics by those who judge a science not by its own nature；
but according to the accidental effects it may have produced； that
it can never be pletely abandoned； that we must always return to it
as to a beloved one who has been for a time estranged； because the
questions with which it is engaged relate to the highest aims of
humanity； and reason must always labour either to attain to settled
views in regard to these； or to destroy those which others have
already established。
Metaphysic； therefore… that of nature； as well as that of ethics；
but in an especial manner the criticism which forms the propaedeutic
to all the operations of reason… forms properly that department of
knowledge which may be termed； in the truest sense of the word；
philosophy。 The path which it pursues is that of science； which；
when it has once been discovered； is never lost； and never misleads。
Mathematics； natural science； the mon experience of men； have a
high value as means； for the most part； to accidental ends… but at
last also； to those which are necessary and essential to the existence
of humanity。 But to guide them to this high goal； they require the aid
of rational cognition on the basis of pure conceptions； which； be it
termed as it may； is properly nothing but metaphysics。
For the same reason； metaphysics forms likewise the pletion of
the culture of human reason。 In this respect； it is indispensable；
setting aside altogether the influence which it exerts as a science。
For its subject…matter is the elements and highest maxims of reason；
which form the basis of the possibility of some sciences and of the
use of all。 That； as a purely speculative science； it is more useful
in preventing error than in the extension of knowledge； does not
detract from its value； on the contrary； the supreme office of
censor which it occupies assures to it the highest authority and
importance。 This office it administers for the purpose of securing
order； harmony； and well…being to science； and of directing its
noble and fruitful labours to the highest possible aim… the
happiness of all mankind。
CHAPTER IV。 The History of Pure Reason。
This title is placed here merely for the purpose of designating a
division of the system of pure reason of which I do not intend to
treat at present。 I shall content myself with casting a cursory
glance； from a purely transcendental point of view… that of the nature
of pure reason… on the labours of philosophers up to the present t