is to the right of B we must
first apprehend empty space. He concludes that our apprehension of
space is _a priori_, because we apprehend empty space _before_ we
become aware of the spatial relations of individual objects in it.

[14] _Begriff_ (conception) here is to be understood loosely
not as something opposed to _Anschauung_ (perception), but as
equivalent to the genus of which _Anschauung_ and _Begriff_
are species, i. e. _Vorstellung_, which maybe rendered by
'representation' or 'idea', in the general sense in which
these words are sometimes used to include 'thought' and
'perception'.

[15] The next sentence shows that 'external' means, not
'produced by something external to the mind', but simply
'spatial'.

[16] B. 38, M. 23-4.

To this the following reply may be made. (_a_) The term _a priori_
applied to an apprehension should mean, not that it arises prior to
experience, but that its validity is independent of experience. (_b_)
That to which the term _a priori_ should be applied is not the
apprehension of empty space, which is individual, but the apprehension
of the nature of space in general, which is universal. (_c_) We do not
apprehend empty space before we apprehend individual spatial relations
of individual bodies or, indeed, at any time. (_d_) Though we come to
apprehend _a priori_ the nature of space in general, the apprehension
is not prior but posterior in time to the apprehension of individual
spatial relations. (_e_) It does not follow from the temporal priority
of our apprehension of individual spatial relations that our
apprehension of the nature of space in general is 'borrowed from
experience', and is therefore not _a priori_.

2. "We can never represent to ourselves that there is no space, though
we can quite well think that no objects are found in it. It must,
therefore, be considered as the condition of the possibility of
phenomena, and not as a determination dependent upon them, and it is
an _a priori_ representation, which necessarily underlies external
phenomena."[17]

[17] B. 38, M. 24.

Here the premise is simply false. If 'represent' or 'think' means
'believe', we can no more represent or think that there are no
objects in space than that there is no space. If, on the other hand,
'represent' or 'think' means 'make a mental picture of', the assertion
is equally false. Kant is thinking of empty space as a kind of
receptacle for o