l as a pure intuition previous
to all experience. So we can only speak of space and of extended
objects from the standpoint of human reason. But when we have abstracted
all the forms perceived by our sensibility, there remains a pure
intuition which we call space. Therefore our discussion teaches us the
objective validity of space with regard to all that can appear before us
externally as an object; but equally the subjective ideality of space,
with regard to things if they are considered in themselves by our
reason, that is, without taking into account the nature of our
sensibility.

Time is not empirically conceived of; that is, it is not experimentally
apprehended. Time is a necessary representation on which all intuitions
are dependent, and the representation of time to the mind is thus given
_a priori._ In it alone can phenomena be apprehended. These may vanish,
but time cannot be put aside.

Time is not something existing by itself independently, but is the
formal condition _a priori_ of all phenomena. If we deduct our own
peculiar sensibility, then the idea of time disappears indeed, because
it is not inherent in any object, but only in the subject which
perceives that object. Space and time are essential _a priori_ ideas,
and they are the necessary conditions of all particular perceptions.
From the latter and their objects we can, in imagination, without
exception, abstract; from the former we cannot.

Space and time are therefore to be regarded as the necessary _a priori_
pre-conditions of the possibility and reality of all phenomena. It is
clear that transcendental aesthetic can obtain only these two elements,
space and time, because all other concepts belong to the senses and
pre-suppose experience, and so imply something empirical. For example,
the concept of motion pre-supposes something moving, but in space
regarded alone there is nothing that moves; therefore, whatever moves
must be recognised by experience, and is a purely empirical datum.

_II.--Transcendental Logic_

Our knowledge is derived from two fundamental sources of the
consciousness. The first is the faculty of receptivity of impressions;
the second, the faculty of cognition of an object by means of these
impressions or representations, this second power being sometimes styled
spontaneity of concepts. By the first, an object is given to us; by the
second it is thought of in the mind. Thus intuition and concepts
constitute the elements o