1. The _synopsis_ of the manifold--_a priori_ through sense, _i.e._ in pure intuition. 2. The synthesis of this manifold--through pure transcendental imagination. 3. The unity of this synthesis--through pure original transcendental apperception. At this point Vaihinger adds to the above section the earlier passage § 10 T.[827] It is even more definitely than III. γ and III. I transitional to the fourth stage. It must be classed within the third stage, as it holds to the above threefold classification. But it modifies that classification in two respects. First, in that it does not employ the term _synopsis_, but only speaks of pure intuition as required to yield us a manifold. The term synopsis, as used by Kant, is, however, decidedly misleading.[828] His invariable teaching is that all connection is due to synthesis. By synopsis, therefore, which he certainly does not employ as synonymous with synthesis, can be meant only apprehension of external side-by-sideness. It never signifies anything except apprehension of the lowest possible order. Kant’s omission of the term, therefore, tends to clearness of statement. Secondly, the classification is also modified by the substitution of understanding for the unity of apperception. Apperception is, however, so obscurely treated in all of the above sections, that this cannot be regarded as a vital alteration. What is new in this section, and seems to connect it in a curious and interesting manner with sections in the fourth stage, is its doctrine of “a manifold of _a priori_ sensibility.” “Space and time contain a manifold of pure _a priori_ intuition.”[829] That is, in this connection, an entirely new doctrine. In all the previous sections of the deduction (previous in the assumed order of original writing) the manifold supplied through intuition is taken as being empirical, and as consisting of sensations. Kant here also adds that the manifold, “whether given empirically or _a priori_,”[830] must be synthesised before it can be known. “The spontaneity of our thought requires that this manifold [of pure _a priori_ intuition] should be run through in a certain manner, taken up, and connected, in order that a knowledge may be formed out of it. This action I call synthesis.”