angles, and we do not need, as in the
case of judgments of experience, to add the limitation, so far as it is yet
known there are no exceptions to this rule. The apriority is the _ratio
essendi_ of the strict necessity involved in the "it must be so" _(des
Soseinmuessens_), while the latter is the _ratio cognoscendi_ of the former.
Now since the necessity of mathematical judgments can only be explained
through the ideality of space, this doctrine is perfectly certain, not
merely a probable hypothesis.--The validity of mathematical principles for
all objects of perception, finally, is based on the fact that they are
rules under which alone experience is possible for us. It should be
mentioned, further, that the conceptions of change and motion (change of
place) are possible only through and in the representation of time. No
concept could make intelligible the possibility of change, that is, of the
connection of contradictory predicates in one and the same thing, but the
intuition of succession easily succeeds in accomplishing it.

The argument is followed by conclusions and explanations based upon it;
(1) Space is the form of the outer, time of the inner, sense. Through the
outer sense external objects are given to us, and through the inner sense
our own inner states. But since all representations, whether they have
external things for their objects or not, belong in themselves, as mental
determinations, to our inner state, time is the formal condition of all
phenomena in general, directly of internal (psychical) phenomena, and,
thereby, indirectly of external phenomena also. (2) The validity of the
relations of space and time cognizable _a priori_ is established for all
objects of possible experience, but is limited to these. They are valid
for _all phenomena_ (for all things which at any time may be given to our
senses), but only for these, not for things as they are _in themselves_.
They have "empirical reality, but, at the same time, transcendental
ideality." As external phenomena all things are beside one another in
space, and all phenomena whatever are in time and of necessity under
temporal relations; in regard to all things which can occur in our
experience, and in so far as they can occur, space and time are
objectively, therefore empirically, real. But they do not possess absolute
reality (neither subsistent reality nor the reality of inherence); for if
we abstract from our sensuous intuition both vanish, and, a