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The purpose of this critique of pure speculative reason consists in the attempt to change the old procedure of metaphysics, and to bring about a complete revolution after the example set by geometers and investigators of nature. This critique is a treatise on the method, not a system of the science itself; but nevertheless it marks out the whole plan of this science, both with regard to its limits and with regard to its inner organization. For it is peculiar to pure speculative reason that it is able, indeed bound, to measure its own powers according to the different ways in which it chooses its objects for thought, and to enumerate exhaustively the different ways of choosing its problems, thus tracing a complete outline of a system of metaphysics. This is due to the fact that, with regard to the first point, nothing can be attributed to objects in *a priori* knowledge, except what the thinking subject takes from within itself; while, with regard to the second point, pure reason, as far as its principles of knowledge are concerned, forms a separate and independent unity, in which, as in an organized body, every member exists for the sake of all the others, and all the others exist for the sake of the one, so that no principle can be safely applied in *one* relation unless it has been carefully examined in *all* its relations to the whole use of pure reason. Hence, too, metaphysics has this singular advantage, an advantage which cannot be shared by any other rational science which has to deal with objects (for *logic* deals only with the form of thought in general), that if by means of this critique it has been set upon the secure course of a science, it can exhaustively grasp the entire field of knowledge pertaining to it, and can thus finish its work and leave it to posterity as a capital that can never be added to, because it has to deal only with principles and with the limitations of their use, as determined by these principles themselves. And this completeness becomes indeed an obligation if metaphysics is to be a fundamental science, of which we must be able to say, *nil actum reputants, si quid superesset agendum* [to think that nothing was done for as long as something remained to be done]."
―from_Critique of Pure Reason_. Preface to the Second Edition. Translated, edited, and with an Introduction by Marcus Weigelt, based on the translation by Max Müller, pp. 21-22
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