. To take the case of cause and effect,
the conception of which, according to Kant, is involved in our
apprehension of a succession, Kant's view seems to be that we become
aware of two elements of the manifold A B as a succession of events in
the world of nature by combining them as necessarily successive in a
causal order, in which the state of affairs which precedes B and which
contains A contains something upon which B must follow (i. e. a cause
of B), which therefore makes it necessary that B must follow A.[6] But
if we are to do this, we must in some way succeed in selecting or
picking out from among the elements of the manifold that element A
which is to be thus combined with B. We therefore need something more
than the category. It is not enough that we should think that B has a
cause; we must think of something in particular as the cause of B,
and we must think of it either as coexistent with, or as identical
with, A.

[6] Cf. pp. 291-3.

Kant fails to notice this second difficulty,[7] and up to a certain
point avoids it owing to his distinction between the imagination and
the understanding. For he thinks of the understanding as the source of
general principles of synthesis, viz. the categories, and attributes
individual syntheses to the imagination. Hence the individual
syntheses, which involve particular principles, are already effected
before the understanding comes into play. But to throw the work of
effecting individual syntheses upon the imagination is only to evade
the difficulty. For in the end, as has been pointed out,[8] the
imagination must be the understanding working unreflectively, and,
whether this is so or not, some account must be given of the way in
which the imagination furnishes the particular principles of synthesis
required.

[7] We should have expected Kant to have noticed this
difficulty in A. 105, Mah. 199, where he describes what is
involved in the relation of representations to an object, for
his instance of representations becoming so related is the
process of combining elements into a triangle, which plainly
requires a synthesis of a very definite kind. For the reasons
of his failure to notice the difficulty cf. p. 207.

[8] Pp. 168-9.

The third and last main difficulty of the first kind concerns the
relation of the elements of the manifold and the kinds of synthesis
by which they are combined. This involves the distinction between
relatin