This synthesis of the manifold of sensuous intuition, which is possible
and necessary à priori, may be called figurative (synthesis speciosa),
in contradistinction to that which is cogitated in the mere category in
regard to the manifold of an intuition in general, and is called
connection or conjunction of the understanding (synthesis
intellectualis). Both are transcendental, not merely because they
themselves precede à priori all experience, but also because they form
the basis for the possibility of other cognition à priori.
But the figurative synthesis, when it has relation only to the
originally synthetical unity of apperception, that is to the
transcendental unity cogitated in the categories, must, to be
distinguished from the purely intellectual conjunction, be entitled the
transcendental synthesis of imagination. Imagination is the faculty of
representing an object even without its presence in intuition. Now, as
all our intuition is sensuous, imagination, by reason of the subjective
condition under which alone it can give a corresponding intuition to
the conceptions of the understanding, belongs to sensibility. But in so
far as the synthesis of the imagination is an act of spontaneity, which
is determinative, and not, like sense, merely determinable, and which
is consequently able to determine sense à priori, according to its
form, conformably to the unity of apperception, in so far is the
imagination a faculty of determining sensibility à priori, and its
synthesis of intuitions according to the categories must be the
transcendental synthesis of the imagination. It is an operation of the
understanding on sensibility, and the first application of the
understanding to objects of possible intuition, and at the same time
the basis for the exercise of the other functions of that faculty. As
figurative, it is distinguished from the merely intellectual synthesis,
which is produced by the understanding alone, without the aid of
imagination. Now, in so far as imagination is spontaneity, I sometimes
call it also the productive imagination, and distinguish it from the
reproductive, the synthesis of which is subject entirely to empirical
laws, those of association, namely, and which, therefore, contributes
nothing to the explanation of the possibility of à priori cognition,
and for this reason belongs not to transcendental philosophy, but to
psychology.