184 PHILO 
edifice of knowledge without even knowing whence we 
have derived the materials, and upon the faith of prin¬ 
ciples whofe origin is unknown to us; but that we ftiould 
previously alfure ourfelves of its folid foundation. We 
ought, therefore, long fince to have enquired how the 
underftanding came by knowledge ii priori, and what are 
its extent, validity, and worth. Nothing indeed could 
be more natural, if we underftand by that word a ra¬ 
tional mode of proceeding ; but, if we underftand by it 
the mode ufually adopted, then nothing is more natural 
or more conceivable than that this inveftigation ftiould 
long remain unperformed ; efpecially as a part of this 
knowledge il priori, the Mathematics, has long been in 
firm poffeflion of infallible certainty, and led to a favour¬ 
able expectation refpeCting other Sciences, though they 
may be of an entirely different nature. Belides, when we 
are out of the Sphere of experience, we are fure not to be 
contradicted by it. The charm of extending our know¬ 
ledge is fo great, that nothing Short of a direCt contradic¬ 
tion can retard our progrefs. This contradiction, how¬ 
ever, may be avoided, if we take care how we conftruCt 
our fictions, which will nevertheless always remain fic¬ 
tions. The mathematics afford us a Splendid example of 
the great extent to which we may carry our knowledge 
il priori, independently of experience ; for they treat of 
objeCts and of knowledge only fo far as the latter are re¬ 
presented in [ intuition . But this circumftance is eafily 
overlooked, becaufe intuition itfelf can be given il priori, 
and is hardly to be dillinguiflied from a pure conception. 
Stimulated by Such a proof of the power of Reafon, the 
defire to extend our knowledge perceives no boundaries. 
The fleet pigeon, while dividing the air in its flight. Sen¬ 
sible of its refiftance, might eafily fancy that it could pafs 
more rapidly through a vacuum. With a Similar view,-, 
Plato quitted the fenfible world, becaufe it limited the'? 
underftanding, and ventured beyond it, on the wings of 
Ideas, into the empty fpace of pure Intellect. He did 
not remark that he gained no ground by his efforts, and 
that he had no firm bafis to reft upon, in order to advance 
his underftanding. It is the ul'ual fate of Human Reafon 
in its fpeculations, to complete its edifice as quickly as 
poffible, and afterwards to enquire into its foundation. 
Then all forts of Subterfuges are reforted to in order to 
Satisfy ourfelves with refpeCl to its Solidity, or rather 
completely to avoid fo fearful an after-thought. That 
which frees us from all care and fufpicion, and flatters us 
with a feeming Solidity during the ereCIion of the edifice, 
is this : a great, and perhaps the greater, part of the bu- 
finefs of reafon confifts in the analyfis of conceptions 
which we have already formed. This furnifhes us with a 
variety of knowledge, which, though it confifts of nothing 
more than explanations or illuftrations of what is already 
confufedly thought in our conceptions, yet it is efteemed 
equal, at leaft in point of form, to a new infight, though, 
with regard to its matter, it does not extend our concep¬ 
tions. Now, as this procedure furnifhes real knowledge 
a priori, which is Safe and ufeful, Reafon, under this il- 
lulion, unconfcioufly adopts aflertions of a totally differ¬ 
ent nature, in which it adds to the given conceptions 
foreign matter, and that H priori, without our knowing 
whence it is derived, and without allowing fuch an en¬ 
quiry to enter our minds. I fha.ll now proceed to fhow 
the difference between thefe two kinds of knowledge. 
IV. Of the Difference between Analytical and Synthetical 
Judgments. 
In all judgments, the relation of the fubjeCt to the pre¬ 
dicate may be of two kinds. I fhall confider only the af¬ 
firmative; as the application to the negative is afterwards 
eafy. Either the predicate B belongs to the fubjeft A, 
as fomething that is contained in the conception A in a 
concealed manner; or B lies entirely out of the conception 
of A, though it ftands in connexion with it. In the 
former cafe, I call the judgment analytical-, in the latter, 
fynthetical. 3 
SOPHY. 
Analytical judgments, therefore, are thofein which the 
connexion of the predicate with the fubjedf is confidered 
identical. Thofe, however, in which this connexion is 
conceived without identity, may be called fynthetical 
judgments. The former are judgment^ of explanation, 
the latter judgments of extenfion; becaufe the former by 
the predicate add nothing to the conception of the fubjedf, 
but only feparate it by analyfis into its conftituent con¬ 
ceptions which are originally thought in it, though in a 
confufed manner; while, on the other hand, the latter 
add a predicate to the conception of the fubjeft which 
was in no way thought in it, and which could not have 
been derived from it by any analyfis. For inftance, All 
bodies are extended: this is an analytical judgment; for I 
need not go beyond the conception body in order to find 
extenfion connected with it; but have only to analyze that 
conception, and become confcious of the variety which I 
always think in it, in order to find this predicate ; it is 
therefore an analytical judgment. On the other hand, if 
I fay, All bodies are heavy; this predicate is fomething 
quite different from that which I think in the mere con¬ 
ception of body. The addition of fuch a predicate is a 
fynthetical j udgment. 
Judgments of experience, as fuch, are altogether fynthe¬ 
tical. For it would be abfurd to ground an analytical 
judgment upon experience, becaufe I need not at all go 
out of my conception in order to comprehend the judg¬ 
ment; confequently no teftimony of experience is required. 
That a body is extended, is a pofition that is evident 
il priori, and not a judgment of experience : for, before I 
proceed to experience, I have all the conditions of my 
judgment already in the conception, from which I only 
derive the predicate according to the principle of contra- 
diSlion, and at the fame time become confcious of the he- 
cejfity of the judgment, which experience could never 
teach me. 
Again, though I do not include in the conception of 
body the predicate heavy, yet that conception indicates 
an objedl of experience by a part of it to which I can ftill 
add other parts of the felf-fame experience, which alfo be¬ 
longed to the former. I previoufly know the conception 
of body analytically by the marks of extenfion, of impe¬ 
netrability, of figure, &cc. which are thought in this con¬ 
ception. But I now increafe my knowledge ; and, while 
I refer back to experience, whence I have derived this 
conception of body, I find, with the above marks, that of 
heavy always connedled; and therefore I add this fynthe- 
tically as a predicate to my conception. The poflibility 
of the fynthefis of the predicate heavy with the conception 
body, is grounded upon experience, becaufe both con¬ 
ceptions belong to one another, though only accidentally: 
indeed the one is not contained in the other; as 
parts of a whole, namely, of experience, which is itfelf a 
fynthetical connexion of intuitions. 
But in fynthetical judgments H priori, this expedient is 
entirely wanting. If I am to go beyond the conception 
A, in order to perceive another conception B in connexion 
with it, now upon what do I fupport myfelf, and by what 
means is this fynthefis poflible, as I have not here the ad¬ 
vantage of looking for it in the field of experience ? Let 
us take the pofition, Every thing that happens has its caufe. 
In the conception of fomething that happens, I think 
indeed an exiftence, previous to which there is a time ; 
and from this analytical judgments may be derived. But 
the conception of Caufe lies entirely out of that concep¬ 
tion, and indicates fomething different from that which 
happens ; it is therefore not at all contained in this latter 
reprefentation. How can I poflibly fay of that which 
happens fomething quite different from it; and to con¬ 
fider the conception of caufe, though indeed not contained 
in it, neverthelefs as belonging to it, and that neceffarily ? 
What is then the unknown —x, upon which the under¬ 
ftanding fupports itfelf, when it expedfs to find, exterior 
to the conception A, a foreign predicate B, which it 
imagines neverthelefs to be conne&ed with it ? It cannot 
