of the law, that the very notion of a cause would entirely
disappear, were we to derive it, like Hume, from a frequent
association of what happens with that which precedes; and the habit
thence originating of connecting representations--the necessity
inherent in the judgement being therefore merely subjective.
Besides, without seeking for such examples of principles existing a
priori in cognition, we might easily show that such principles are
the indispensable basis of the possibility of experience itself, and
consequently prove their existence a priori. For whence could our
experience itself acquire certainty, if all the rules on which it
depends were themselves empirical, and consequently fortuitous? No
one, therefore, can admit the validity of the use of such rules as
first principles. But, for the present, we may content ourselves
with having established the fact, that we do possess and exercise a
faculty of pure a priori cognition; and, secondly, with having pointed
out the proper tests of such cognition, namely, universality and
necessity.

Not only in judgements, however, but even in conceptions, is an a
priori origin manifest. For example, if we take away by degrees from
our conceptions of a body all that can be referred to mere sensuous
experience--colour, hardness or softness, weight, even
impenetrability--the body will then vanish; but the space which it
occupied still remains, and this it is utterly impossible to
annihilate in thought. Again, if we take away, in like manner, from
our empirical conception of any object, corporeal or incorporeal,
all properties which mere experience has taught us to connect with
it, still we cannot think away those through which we cogitate it as
substance, or adhering to substance, although our conception of
substance is more determined than that of an object. Compelled,