d without understanding no object would be thought. Thoughts without
content are empty, perceptions without conceptions are blind. Hence it
is as necessary for the mind to make its conceptions sensuous (i. e.
to add to them the object in perception) as to make its perceptions
intelligible (i. e. to bring them under conceptions). Neither of these
powers or faculties can exchange its function. The understanding
cannot perceive, and the senses cannot think. Only by their union can
knowledge arise."[4]

[2] B. 29, M. 18

[3] For the sake of uniformity _Vorstellung_ has throughout
been translated by 'representation', though sometimes, as in
the present passage, it would be better rendered by
'presentation'.

[4] B. 74-5, M. 45-6.

The distinction so stated appears straightforward and, on the
whole,[5] sound. And it is fairly referred to by Kant as the
distinction between the faculties of perceiving and conceiving or
thinking, provided that the terms perceiving and conceiving or
thinking be taken to indicate a distinction within perception in the
ordinary sense of the word. His meaning can be stated thus: 'All
knowledge requires the realization of two conditions; an individual
must be presented to us in perception, and we as thinking beings must
bring this individual under or recognize it as an instance of some
universal. Thus, in order to judge 'This is a house' or 'That is red'
we need the presence of the house or of the red colour in perception,
and we must 'recognize' the house or the colour, i. e. apprehend the
individual as a member of a certain kind. Suppose either condition
unrealized. Then if we suppose a failure to conceive, i. e. to
apprehend the individual as a member of some kind, we see that our
perception--if it could be allowed to be anything at all--would be
blind i. e. indeterminate, or a mere 'blur'. What we perceived would
be for us as good as nothing. In fact, we could not even say that we
were perceiving. Again, if we suppose that we had merely the
conception of a house, and neither perceived nor had perceived an
individual to which it applied, we see that the conception, being
without application, would be neither knowledge nor an element in
knowledge. Moreover, the content of a conception is derived from
perception; it is only through its relation to perceived individuals
that we become aware of a universal. To know the meaning of 'redness'
we must have experienced individ