that space, if real at all, must be a property of things in
themselves, whereas the _Aesthetic_ has as he thinks, shown that space
can be, and in point of fact is, a property of phenomena. He now wants
to prove--compatibly with their character as phenomena--that the
existence of bodies in space is not even, as Descartes contends,
_doubtful_. To prove this he seeks to show that Descartes is wrong in
supposing that we have no immediate experience of these objects. His
method is to argue that reflection shows that internal experience
presupposes external experience, i. e. that unless we were directly
aware of spatial objects, we could not be aware of the succession of
our own states, and consequently that it is an inversion to hold that
we must reach the knowledge of objects in space, if at all, by an
inference from the immediate apprehension of our own states.

An examination of the proof itself, however, forces us to allow that
Kant, without realizing what he is doing, really abandons the view
that objects in space are phenomena, and uses an argument the very
nature of which implies that these objects are things in themselves.
The proof runs thus:

_Theorem._ "The mere but empirically determined consciousness of my
own existence proves the existence of objects in space external to
me."

"_Proof._ I am conscious of my own existence as determined in
time. All time-determination presupposes something permanent in
perception.[5] This permanent, however, cannot be an intuition[6]
in me. For all grounds of determination of my own existence, which
can be found in me, are representations, and as such themselves need
a permanent different from them, in relation to which their change
and consequently my existence in the time in which they change can
be determined.[7] The perception of this permanent, therefore, is
possible only through a _thing_ external to me, and not through the
mere _representation_ of a thing external to me. Consequently, the
determination of my existence in time is possible only through the
existence of actual things, which I perceive external to me. Now
consciousness in time is necessarily connected with the consciousness
of the possibility of this time-determination; hence it is necessarily
connected also with the existence of things external to me, as the
condition of time-determination, i. e. the consciousness of my own
existence, is at the same time an immediate consciousness of the
existence of othe