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

^ In the same manner the laws of gravity, determining the movements of the heavenly bodies, imparted the character of established certainty to what Copernicus had assumed at first as an hypothesis only, and proved at the same time the invisible force (the Newtonian attraction) which holds the universe together, which would have remained for ever undiscovered, if Copernicus had not dared, by an hypothesis, 'which, though contradicting the senses, was yet true, to seek the observed movements, not in the heavenly bodies, but in the spectator. I also propose in this preface my own view of metaphysics, which has so many analogies with the Copernican hypothesis, as an hypothesis only, though, in the Critique itself, it is proved by means of our representations of space and time, and the elementary concepts of the understanding, not hypothetically, but apodictically; for T wish that people should observe the first attempts at such a change, which must always be hypothetical.

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This is due to the fact that, with regard to the first point, nothing can be attributed to objects in knowledge a priori, except what the thinking subject takes from within itself; while, with regard to the second point, reason, so far as its principles of cognition are concerned, forms a separate and independent unity, in which, as in an organic body, every member exists for the sake of all others, and all 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 employment of pure reason.

Hence, too, metaphysic has this singular advantage, an advantage which cannot be shared by any other science, in which reason has to deal with objects (for Logic deals only with the form of thought in general) that, if it has once attained, by means of this critique, to the secure method of a science, it can completely comprehend the whole field of know- [p. xxiv] ledge pertaining to it, and thus finish its work and leave it to posterity, as a capital that can never be added to, because it has only to deal with principles and the limits of their employment, which are fixed by those principles themselves.

And this completeness becomes indeed an obligation, if it is to be a fundamental science, of which we must be able to say, * nil aciutn reputans, si quid superesset agendum.^

But it will be asked, what kind of treasure is it which we mean to bequeath to posterity in this metaphysic of ours, after it has been purified by criticism, and thereby brought to a permanent condition ? After a superficial view of this work, it may seem that its advantage is negative only, warning us against venturing with speculative reason beyond the limits of experience. Such is no doubt its primary use : but it becomes positive, when we perceive that the principles with which speculative reason ventures beyond its limits, lead inevitably, not to an extension, but, if carefully considered, to a nari'owing of the employment of reason, because, by indefinitely extending the limits of sensibiHty, to which [p. xxv] they properly belong, they threaten entirely to supplant the pure (practical) employment of reason. Hence our critique, by limiting sensibility to its proper sphere, is no doubt negative ; but by thus removing an impediment, which threatened to narrow, or

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