from sensibility； that is； they cannot be applied to an object。 They
are merely the pure form of the employment of the understanding in
respect of objects in general and of thought； without its being at the
same time possible to think or to determine any object by their means。
But there lurks at the foundation of this subject an illusion
which it is very difficult to avoid。 The categories are not based；
as regards their origin； upon sensibility； like the forms of
intuition； space； and time； they seem； therefore； to be capable of
an application beyond the sphere of sensuous objects。 But this is
not the case。 They are nothing but mere forms of thought； which
contain only the logical faculty of uniting a priori in
consciousness the manifold given in intuition。 Apart； then； from the
only intuition possible for us； they have still less meaning than
the pure sensuous forms； space and time； for through them an object is
at least given； while a mode of connection of the manifold； when the
intuition which alone gives the manifold is wanting； has no meaning at
all。 At the same time； when we designate certain objects as
phenomena or sensuous existences； thus distinguishing our mode of
intuiting them from their own nature as things in themselves； it is
evident that by this very distinction we as it were place the
latter； considered in this their own nature； although we do not so
intuite them； in opposition to the former； or； on the other hand； we
do so place other possible things； which are not objects of our
senses； but are cogitated by the understanding alone； and call them
intelligible existences （noumena）。 Now the question arises whether the
pure conceptions of our understanding do possess significance in
respect of these latter； and may possibly be a mode of cognizing them。
But we are met at the very mencement with an ambiguity； which may
easily occasion great misapprehension。 The understanding； when it
terms an object in a certain relation phenomenon； at the same time
forms out of this relation a representation or notion of an object
in itself； and hence believes that it can form also conceptions of
such objects。 Now as the understanding possesses no other
fundamental conceptions besides the categories； it takes for granted
that an object considered as a thing in itself must be capable of
being thought by means of these pure conceptions； and is thereby led
to hold the perfectly undetermined conception of an intelligible
existence； a something out of the sphere of our sensibility； for a
determinate conception of an existence which we can cognize in some
way or other by means of the understanding。
If； by the term noumenon； we understand a thing so far as it is
not an object of our sensuous intuition； thus making abstraction of
our mode of intuiting it； this is a noumenon in the negative sense
of the word。 But if we understand by it an object of a non…sensuous
intuition； we in this case assume a peculiar mode of intuition； an
intellectual intuition； to wit； which does not； however； belong to us；
of the very possibility of which we have no notion… and this is a
noumenon in the positive sense。
The doctrine of sensibility is also the doctrine of noumena in the
negative sense； that is； of things which the understanding is
obliged to cogitate apart from any relation to our mode of
intuition； consequently not as mere phenomena； but as things in
themselves。 But the understanding at the same time prehends that it
cannot employ its categories for the consideration of things in
themselves； because these possess significance only in relation to the
unity of intuitions in space and time； and that they are petent
to determine this unity by means of general a priori connecting
conceptions only on account of the pure ideality of space and time。
Where this unity of time is not to be met with； as is the case with
noumena； the whole use； indeed the whole meaning of the categories
is entirely lost； for even the possibility of things to correspond
to the categories is in this case inprehensible。 On this point； I
need only refer the reader to what I have said at the mencement
of the General Remark appended to the foregoing chapter。 Now； the
possibility of a thing can never be proved from the fact that the
conception of it is not self…contradictory； but only by means of an
intuition corresponding to the conception。 If； therefore； we wish to
apply the categories to objects which cannot be regarded as phenomena；
we must have an intuition different from the sensuous； and in this
case the objects would be a noumena in the positive sense of the word。
Now； as such an intuition； that is； an intellectual intuition； is no
part of our faculty of cognition； it is absolutely impossible for
the categories to possess any application beyond the limits of
experience。 It may be true that there are intelligible existences to
which our faculty of sensuous intuition has no relation； and cannot be
applied； but our conceptions of the understanding； as mere forms of
thought for our sensuous intuition； do not extend to these。 What；
therefore； we call noumenon must be understood by us as such in a
negative sense。
If I take away from an empirial intuition all thought （by means of
the categories）； there remains no cognition of any object； for by
means of mere intuition nothing is cogitated； and； from the
existence of such or such an affection of sensibility in me； it does
not follow that this affection or representation has any relation to
an object without me。 But if I take away all intuition； there still
remains the form of thought； that is； the mode of determining an
object for the manifold of a possible intuition。 Thus the categories
do in some measure really extend further than sensuous intuition；
inasmuch as they think objects in general； without regard to the
mode （of sensibility） in which these objects are given。 But they do
not for this reason apply to and determine a wider sphere of
objects； because we cannot assume that such can be given； without
presupposing the possibility of another than the sensuous mode of
intuition； a supposition we are not justified in making。
I call a conception problematical which contains in itself no
contradiction； and which is connected with other cognitions as a
limitation of given conceptions； but whose objective reality cannot be
cognized in any manner。 The conception of a noumenon； that is； of a
thing which must be cogitated not as an object of sense； but as a
thing in itself （solely through the pure understanding）； is not
self…contradictory； for we are not entitled to maintain that
sensibility is the only possible mode of intuition。 Nay； further； this
conception is necessary to restrain sensuous intuition within the
bounds of phenomena； and thus to limit the objective validity of
sensuous cognition； for things in themselves； which lie beyond its
province； are called noumena for the very purpose of indicating that
this cognition does not extend its application to all that the
understanding thinks。 But； after all； the possibility of such
noumena is quite inprehensible； and beyond the sphere of phenomena；
all is for us a mere void； that is to say； we possess an understanding
whose province does problematically extend beyond this sphere； but
we do not possess an intuition； indeed； not even the conception of a
possible intuition； by means of which objects beyond the region of
sensibility could be given us； and in reference to which the
understanding might be employed assertorically。 The conception of a
noumenon is therefore merely a limitative conception and therefore
only of negative use。 But it is not an arbitrary or fictitious notion；
but is connected with the limitation of sensibility； without； however；
being capable of presenting us with any positive datum beyond this
sphere。
The division of objects into phenomena and noumena； and of the world
into a mundus sensibilis and intelligibilis is therefore quite
inadmissible in a positive sense； although conceptions do certainly
admit of such a division； for the class of noumena have no determinate
object corresponding to them； and cannot therefore possess objective
validity。 If we abandon the senses； how can it be made conceivable
that the categories （which are the only conceptions that could serve
as conceptions for noumena） have any sense or meaning at all； inasmuch
as something more than the mere unity of thought； namely； a possible
intuition； is requisite for their application to an object？ The
conception of a noumenon； considered as merely problematical； is；
however； not only admissible； but； as a limitative conception of
sensibility； absolutely necessary。 But； in this case； a noumenon is
not a particular intelligible object for our understanding； on the
contrary； the kind of understanding to which it could belong is itself
a problem； for we cannot form the most distant conception of the
possibility of an understanding which should cognize an object； not
discursively by means of categories； but intuitively in a non…sensuous
intuition。 Our understanding attains in this way a sort of negative
extension。 That is to say； it is not limited by； but rather li