that it antecedes all conceptions； although it presupposes a synthesis
which does not belong to sense； through which alone； however； all
our conceptions of space and time are possible。 For as by means of
this unity alone （the understanding determining the sensibility） space
and time are given as intuitions； it follows that the unity of this
intuition a priori belongs to space and time； and not to the
conception of the understanding （SS 20）。
When； then； for example； I make the empirical intuition of a house
by apprehension of the manifold contained therein into a perception；
the necessary unity of space and of my external sensuous intuition
lies at the foundation of this act； and I； as it were； draw the form
of the house conformably to this synthetical unity of the manifold
in space。 But this very synthetical unity remains； even when I
abstract the form of space； and has its seat in the understanding； and
is in fact the category of the synthesis of the homogeneous in an
intuition； that is to say； the category of quantity； to which the
aforesaid synthesis of apprehension； that is； the perception； must
be pletely conformable。*
*In this manner it is proved； that the synthesis of apprehension；
which is empirical； must necessarily be conformable to the synthesis
of apperception； which is intellectual； and contained a priori in
the category。 It is one and the same spontaneity which at one time；
under the name of imagination； at another under that of understanding；
produces conjunction in the manifold of intuition。
To take another example； when I perceive the freezing of water； I
apprehend two states （fluidity and solidity）； which； as such； stand
toward each other mutually in a relation of time。 But in the time；
which I place as an internal intuition； at the foundation of this
phenomenon； I represent to myself synthetical unity of the manifold；
without which the aforesaid relation could not be given in an
intuition as determined （in regard to the succession of time）。 Now
this synthetical unity； as the a priori condition under which I
conjoin the manifold of an intuition； is； if I make abstraction of the
permanent form of my internal intuition （that is to say； of time）； the
category of cause； by means of which； when applied to my
sensibility； I determine everything that occurs according to relations
of time。 Consequently apprehension in such an event； and the event
itself； as far as regards the possibility of its perception； stands
under the conception of the relation of cause and effect： and so in
all other cases。
Categories are conceptions which prescribe laws a priori to
phenomena； consequently to nature as the plex of all phenomena
（natura materialiter spectata）。 And now the question arises…
inasmuch as these categories are not derived from nature； and do not
regulate themselves according to her as their model （for in that
case they would be empirical）… how it is conceivable that nature
must regulate herself according to them； in other words； how the
categories can determine a priori the synthesis of the manifold of
nature； and yet not derive their origin from her。 The following is the
solution of this enigma。
It is not in the least more difficult to conceive how the laws of
the phenomena of nature must harmonize with the understanding and with
its a priori form… that is； its faculty of conjoining the manifold…
than it is to understand how the phenomena themselves must
correspond with the a priori form of our sensuous intuition。 For
laws do not exist in the phenomena any more than the phenomena exist
as things in themselves。 Laws do not exist except by relation to the
subject in which the phenomena inhere； in so far as it possesses
understanding； just as phenomena have no existence except by
relation to the same existing subject in so far as it has senses。 To
things as things in themselves； conformability to law must necessarily
belong independently of an understanding to cognize them。 But
phenomena are only representations of things which are utterly unknown
in respect to what they are in themselves。 But as mere
representations； they stand under no law of conjunction except that
which the conjoining faculty prescribes。 Now that which conjoins the
manifold of sensuous intuition is imagination； a mental act to which
understanding contributes unity of intellectual synthesis； and
sensibility； manifoldness of apprehension。 Now as all possible
perception depends on the synthesis of apprehension； and this
empirical synthesis itself on the transcendental； consequently on
the categories； it is evident that all possible perceptions； and
therefore everything that can attain to empirical consciousness；
that is； all phenomena of nature； must； as regards their
conjunction； be subject to the categories。 And nature （considered
merely as nature in general） is dependent on them。 as the original
ground of her necessary conformability to law （as natura formaliter
spectata）。 But the pure faculty （of the understanding） of
prescribing laws a priori to phenomena by means of mere categories； is
not petent to enounce other or more laws than those on which a
nature in general； as a conformability to law of phenomena of space
and time； depends。 Particular laws； inasmuch as they concern
empirically determined phenomena； cannot be entirely deduced from pure
laws； although they all stand under them。 Experience must be
superadded in order to know these particular laws； but in regard to
experience in general； and everything that can be cognized as an
object thereof； these a priori laws are our only rule and guide。
Result of this Deduction of the Conceptions of the
Understanding。 SS 23
We cannot think any object except by means of the categories； we
cannot cognize any thought except by means of intuitions corresponding
to these conceptions。 Now all our intuitions are sensuous； and our
cognition； in so far as the object of it is given； is empirical。 But
empirical cognition is experience； consequently no a priori
cognition is possible for us； except of objects of possible
experience。*
*Lest my readers should stumble at this assertion； and the
conclusions that may be too rashly drawn from it； I must remind them
that the categories in the act of thought are by no means limited by
the conditions of our sensuous intuition； but have an unbounded sphere
of action。 It is only the cognition of the object of thought； the
determining of the object； which requires intuition。 In the absence of
intuition； our thought of an object may still have true and useful
consequences in regard to the exercise of reason by the subject。 But
as this exercise of reason is not always directed on the determination
of the object； in other words； on cognition thereof； but also on the
determination of the subject and its volition； I do not intend to
treat of it in this place。
But this cognition； which is limited to objects of experience； is
not for that reason derived entirely； from； experience； but… and
this is asserted of the pure intuitions and the pure conceptions of
the understanding… there are； unquestionably； elements of cognition；
which exist in the mind a priori。 Now there are only two ways in which
a necessary harmony of experience with the conceptions of its
objects can be cogitated。 Either experience makes these conceptions
possible； or the conceptions make experience possible。 The former of
these statements will not bold good with respect to the categories
（nor in regard to pure sensuous intuition）； for they are a priori
conceptions； and therefore independent of experience。 The assertion of
an empirical origin would attribute to them a sort of generatio
aequivoca。 Consequently； nothing remains but to adopt the second
alternative （which presents us with a system； as it were； of the
epigenesis of pure reason）； namely； that on the part of the
understanding the categories do contain the grounds of the possibility
of all experience。 But with respect to the questions how they make
experience possible； and what are the principles of the possibility
thereof with which they present us in their application to
phenomena； the following section on the transcendental exercise of the
faculty of judgement will inform the reader。
It is quite possible that someone may propose a species of
preformation…system of pure reason… a middle way between the two… to
wit； that the categories are neither innate and first a priori
principles of cognition； nor derived from experience； but are merely
subjective aptitudes for thought implanted in us contemporaneously
with our existence； which were so ordered and disposed by our Creator；
that their exercise perfectly harmonizes with the laws of nature which
regulate experience。 Now； not to mention that with such an
hypothesis it is impossible to say at what point we must stop in the
employment of predetermined aptitudes； the fact that the categories
would in this case entirely lose that character of necessity which
is essentially involved in the very conception of them； is a
conclusive objection to it。 The conception of cause； for example；
which expresses the necessity of an effect u