From these remarks, the reader of the Critique of Pure Speculative Reason will be thoroughly convinced how highly necessary that laborious deduction of the categories was, and how fruitful for theology and morals. For if, on the one hand, we place them in pure understanding, it is by this deduction alone that we can be prevented from regarding them, with Plato, as innate, and founding on them extravagant pretensions to theories of the supersensible, to which we can see no end, and by which we should make theology a magic lantern of chimeras; on the other hand, if we regard them as acquired, this deduction saves us from restricting, with Epicurus, all and every use of them, even for practical purposes, to the objects and motives of the senses. But now that the Critique has shown by that deduction, first, that they are not of empirical origin, but have their seat and source a priori in the pure understanding; secondly, that as they refer to objects in general independently of the intuition of them, hence, although they cannot effect theoretical knowledge, except in application to empirical objects, yet when applied to an object given by pure practical reason they enable us to conceive the supersensible definitely, only so far, however, as it is defined by such predicates as are necessarily connected with the pure practical purpose given a priori and with its possibility. The speculative restriction of pure reason and its practical extension bring it into that relation of equality in which reason in general can be employed suitably to its end, and this example proves better than any other that the path to wisdom, if it is to be made sure and not to be impassable or misleading, must with us men inevitably pass through science; but it is not till this is complete that we can be convinced that it leads to this goal. {BOOK_2|CHAPTER_2 ^paragraph 85} VIII. Of Belief from a Requirement of Pure Reason.