Immanuel Kant's Critique of Pure Reason — trans. F. Max Müller

There is one thing, however, of which, in the above demonstration, I could not make abstraction : namely, that the manifold for an intuition must be given antecedently to the synthesis of the understanding, and independently of it; — how, remains uncertain. P'or if I were to imagine an understanding, itself intuitive (for instance, a divine understanding, which should not represent to itself given objects, but produce them at once by his representation), the categories would have no meaning with respect to such cognition. They are merely rules for an understanding whose whole power consists in thinking, that is, in the act of bringing the synthesis of the manifold, which is given to it in intuition from elsewhere, to the unity of apperception ; an understanding which therefore knows nothing by itself, but connects only and arranges the material for cognition, that is, the intuition which must be given to it by the object. This peculiarity of our understanding of producing unity of apperception a priori by means of the categories only, and again by such and so many, cannot be further explained, any more than why we have these and no other functions of judgment, and why time and space are the only forms of a possible intuition for us.

§ 22

The Category admits of no other Employrnent for the Cognition of Things, but its Application to Objects of Expe?ience

We have seen that to think an object is not the same as to know an object. In order to know an object, we must have the concept by which any object is thought (the category), and likewise the intuition by which it is given. If no corresponding intuition could be given to a concept, it would still be a thought, so far as its form is concerned : but it would be without an object, and no knowledge of anything would be possible by it, because, so far as I know, there would be nothing, and there could be nothing, to which ray thought could be referred. Now the only possible intuition for us is sensuous (see Esthetic) ; the thought of any object, therefore, by means of a pure concept of the understanding, can with us become knowledge only, if it is referred to

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objects of the senses. Sensuous intuition is either pure (space and time), or empirical, i.e. if it is an intuition of that which is represented in space and time, through sensation as immediately real. By means of pure intuition we can gain knowledge a prio7'i of things as phenomena (in mathematics), but only so far as their form is concerned ; but whether there are things which must be perceived, according to that form, remains unsettled. Mathematical concepts, by themselves, therefore, are not yet knowledge, except under the supposition that there are things which admit of being represented by us, according to the form of that pure sensuous intuition only. Consequently, as things in space and time are only given as perceptions (as representations accompanied by sensations), that is, through empirical representations, the pure concepts of the understanding, even if applied to intuitions a priori^ as in mathematics, give us knowledge in so far only as these pure intuitions, and therefore through them the concepts of the understanding also, can be applied to empirical intuitions. Consequently the categories, by means of intuition, do not give us any knowledge of things, except under the supposition of their possible application to empirical intuition; they serve, in short, for the possibihty of empirical knowledge only, which is called experience. From this it follows that the categories admit of no other employment for the cognition of things, except so far only as these are taken as objects of possible experience.

§ 23