M E T A 'PHYSIC S, 
Selves, of which I can hnow nothing. This dodtrine of 
Time and Space, therefore, is fo far from destroying the 
reality of the fenfible world, that, on the contrary, it is 
by its means alone that the mathematics, which might 
otherwife be taken for a mere phantom, are fecured in 
their application to real objedts ; Since we never Should 
be able to (how, independent of this dodtrine that the 
Intuitions of Time and Space, which we do not borrow 
from experience, and which, notwithstanding, lie in our 
reprefentations a priori, are not mere creations of the 
mind with which no objedt corresponds ; and therefore 
Geometry itfelf might be a mere chimera, whereas we 
are now able to prove the legitimacy of its application 
to the whole fenlible world, upon the foie principle.that 
that world coniilts merely of phenomena. 
When I aifert that fenfible representations are mere 
phenomena, So far am I from turning the truth and -rea¬ 
lity of experience into mere fidtion, that it is by this 
means alone I am able to overturn the old tranfcendental 
Jiftion, by which Metaphyfics have at all times been led 
on in the purfuit of a bubble, mistaking fenfible repre¬ 
fentations of things for things in themfelves; whence 
arofe all thofe remarkable paradoxes which I have termed 
antinomies of Real'on, of which I Shall hereafter take no¬ 
tice ; and which are at once obviated by admitting the 
Simple truth, that lenfible phenomena, fo long as they are 
limited to human experience, contain truth; but, when 
carried beyond this boundary, and rendered tranfeendent, 
produce nothing but the mereft fidtion. 
As I leave to the things their reality, and limit only 
our fenfible intuition of them, which in no refpedt, not 
even in the forms of Time and Space, reprefents any qua¬ 
lity of thefe things in themfelves, this is not a conversion 
of every thing into mere appearance; and my refutation of 
the charge of Idealism is fo clear and Strong, that it would 
be quite Superfluous were it not for Some incompetent 
judges, who, unwilling to find any thing new that differs 
from their perverfe though common opinion, and not en¬ 
tering into the Spirit of philosophical appellations, but ad¬ 
hering to the latter, are apt to fubSlitute their own erro¬ 
neous ideas in the place of well-determined conceptions, 
and thus to pervert and deform them. My having given to 
this Theory the name of “Transcendental Idealism,” 
is no reafon why it Should be confounded with the empi¬ 
rical idealilin of Des Cartes, or with the myftical and 
fanatical idealifm of Berkley, to both of which it is in¬ 
deed the proper antidote. For the term IdealiJ'm, as I 
have uSed it, does not refer to the existence of the things 
in themfelves ; for to doubt this never entered my mind; 
it merely charadterifes our Sensible representation of them. 
I indeed added the term Transcendental for the Sole 
purpofe of preventing this misconception: but I am by 
no means folicitous to retain this appellation, and am 
willing to term it “ Critical Idealifm." But, if that Idealilin 
be- indeed idle and abfurd, which changes real things into 
mere representations, what epithet Shall we apply to that 
which converts mere representations into things ? It 
might perhaps not improperly be called the dreaming 
Idealifm, to distinguish it from the former, which may be 
called the fanatical; both of which, however, are obviated 
by the Critical Idealism. 
Second Tranfcendental Question. 
How is pare Natural Pliilofophy poffihle? 
Nature is the existence of things So far as it is deter¬ 
mined by univerfal laws. * If nature Signified the existence 
of things in themfelves, we could never have any know¬ 
ledge of it, neither a priori nor a pojteriori. 
Not a priori, for by merely analyzing my conceptions 
I can never difeover what the things are in themfelves, 
independent of conception. My understanding, and the 
conditions under which alone it can reprefent the exist¬ 
ence of things, preferibes to the things themfelves no rule ; 
they do not conform to my understanding, and for me 
to know them it would be neceflary that my underltand- 
2 IS 
ing Should conform to them, and that they Should be 
previoufly given to me; but this would not be to know 
them a priori. Nor is Such a knowledge of the things in 
themfelves poSfible ci pojteriori. For, if experience teaches 
me the laws of the exiitence of things as things in them¬ 
felves, thefe laws muft apply to them necefl'arily, inde¬ 
pendent of my experience. Now experience, indeed, 
teaches me that a thing actually exists, and how it exists, 
but not that it exifts lb necefiarily as that it could not 
be otherwise ; consequently experience cannot teach me 
the nature of the things in themfelves. 
Yet we are in pofFeffion of a pure natural pliilofophy, 
which treats a priori, and with all that neceifity which is 
requisite for apodidtical positions, of the law's under which 
nature Stands. In this fcience the principles of mathe¬ 
matics, as well as dilcurfive principles, are applied to the 
phenomena of Nature. This constitutes the philofophi- 
cal part of the pure knowledge of nature. There are, 
however, many things derived from experience; as, the 
conception of motion, of impenetrability, of vis-inertia'. See. 
upon which the empirical conception of matters relts, So 
that the Knowledge of Nature is not entirely a pure 
Science. It refers alio only to objedts of external fenfe. 
The fcience of nature, then, is not entirely pure; for, if it 
were, it would give laws to the whole of nature, to the 
objedts of the internal as well as of the external fenfes, 
Piycology as well as Natural Pliilofophy. But, among 
the principles of natural pliilofophy, we find Some that are 
pure and univerfal; for instance, that Subjtauce is perma¬ 
nent, that every event has a cauje, &c. Thefe are really 
univerfal laws of nature, and are completely a priori. 
We have therefore a pure Science of nature; and the 
queftion now is, How is this Science poSfible ? 
The word Nature has however another Signification 
which determines the object, while the former denotes only 
the laws of the exiitence of things in general. Nature 
materially considered, is the aggregate of all the objedts 
of experience. In order to know the things according to 
their own nature, not merely as objedts of experience, we 
Should require conceptions of things fuperfenfible, and 
could never discover whether they referred to real ob¬ 
jedts or were mere produdtions of the mind. That which 
cannot be an objedt of experience would require a hyper- 
phyjical knowledge, with which we are not endowed. We 
have only to do with that knowledge of Nature whofe 
reality can be confirmed by experience, though it may 
be a priori, and precede experience. 
Nature, formally considered, is the legitimacy of all the 
objedts of experience; and, as it is known a priori, it is 
neceflary. But we have Seen that the laws of Nature, as 
referring to things in themfelves, can never be known 
a priori. But we lay aflde this idle enquiry relpedting 
the things in themlelves, and confine ourfelves to the 
knowledge of things as objedts of poifibie experience 
(phenomena): properly Speaking, it is the aggregate of 
thefe objedts which constitutes Nature. 
We have now, therei'ore, only to confider Experience, 
and its universal conditions a priori, and hence to jud'>c 
of Nature as the objedt of all pollible experience. I trull 
I Shall not be fuppoi'ed here to mean conditions drawn 
from the obfervation of a Nature already given, and which 
would prei'uppole experience, nor to enquire how we are 
able to learn from experience the laws of Nature, which 
fo learned, would not be a priori, nor furnish any pure 
Science of Nature. The question I would aSk, is, How 
it happens that the conditions of the poflibiiity of expe¬ 
rience d priori, are at the fame time the Sources from 
which the laws of Nature mull be derived ? 
We mult therefore firil remark, that, though all judg¬ 
ments of experience are empirical, i. e. have their ground tn 
the immediate apprehension of the fenfes, yet it does not 
follow that all empirical judgments are judgments of ex¬ 
perience ; for, in addition to every thing empirical, and to 
all fenfible intuition, certain conceptions are Still requi¬ 
site, which have their origin wholly d priori in pure Hi - 
detjiuuclingy 
