Now for this purpose he hit upon the table of judgments, out of which he constructed, as well as he could, the table of categories, the doctrine of twelve pure _a priori_ conceptions, which are supposed to be the conditions of our _thinking_ those very _things_ the _perception_ of which is conditioned by the two _a priori_ forms of sensibility: thus a _pure understanding_ now corresponded symmetrically to a _pure sensibility_. Then another consideration occurred to him, which offered a means of increasing the plausibility of the thing, by the assumption of the _schematism_ of the pure conceptions of the understanding. But just through this the way in which his procedure had, unconsciously indeed, originated betrayed itself most distinctly. For because he aimed at finding something _a priori_ analogous to every empirical function of the faculty of knowledge, he remarked that between our empirical perception and our empirical thinking, conducted in abstract non-perceptible conceptions, a connection very frequently, though not always, takes place, because every now and then we try to go back from abstract thinking to perception; but try to do so merely in order really to convince ourselves that our abstract thought has not strayed far from the safe ground of perception, and perhaps become exaggeration, or, it may be, mere empty talk; much in the same way as, when we are walking in the dark, we stretch out our hand every now and then to the guiding wall. We go back, then, to the perception only tentatively and for the moment, by calling up in imagination a perception corresponding to the conceptions which are occupying us at the time—a perception which can yet never be quite adequate to the conception, but is merely a temporary _representative_ of it. I have already adduced what is needful on this point in my essay on the principle of sufficient reason, § 28. Kant calls a fleeting phantasy of this kind a schema, in opposition to the perfected picture of the imagination. He says it is like a monogram of the imagination, and asserts that just as such a schema stands midway between our abstract thinking of empirically obtained conceptions, and our clear perception which comes to us through the senses, so there are _a priori schemata of the pure conceptions of the understanding_ between the faculty of perception _a priori_ of pure sensibility and the faculty of thinking _a priori_ of the pure understanding (thus the categories). These schemata, as monograms of the pure imagination _a priori_, he describes one by one, and assigns to each of them its corresponding category, in the wonderful “Chapter on the Schematism of the Pure Conceptions of the Understanding,” which is noted as exceedingly obscure, because no man has ever been able to make anything out of it. Its obscurity, however, vanishes if it is considered from the point of view here indicated, but there also comes out more clearly in it than anywhere else the intentional