366 KANT. is impossible to prove it dogmatically. Here the only- possible proof for it, the critical proof, is given •. the principle of permanence is a necessary condition of expe- rience. The same argument establishes the principle of sufficient reason, and the principle of the community of substances, together with the unity of the world to be inferred from this. The three Analogies together assert: "All phenomena exist in one nature and must so exist, because without such a unity a priori no unity of expe. rience, and therefore no determination of objects in expe- rience, would be possible." — In connection with the Postu- lates the same transcendental proof is given for a series of other laws of nature a priori, viz., that in the course of the changes in the world — for the causal principle holds only for effects in nature, not for the existence of things as substances — there can be neither blind chance nor a blind necessity (but only a conditional, hence an intelligible, necessity); and, further, that in the series of phenomena, there can be neither leap, nor gap, nor break, and hence no void — in mundo non datur casus, non datur faium, non datur saltus^ 7ion datur hiatus. j While the dynamical principles have to do with the rela- I tion of phenomena, whether it be to one another (Analo- gies), or to our faculty of cognition (Postulates), the mathematical relate to the quantity of intuitions and sen- ^ sations, and furnish the basis for the application of mathe- matics to natural science.* An extensive quantity is one in which the representation of the parts makes the representa- tion of the whole possible, and so precedes it. I cannot
- represent a line without drawing it in thought, i. e., with-
- In each particular science of nature, science proper (t. *., apodictically
certain science) is found only to the extent in which mathematics can be ap- plied therein. For this reason chemistry can never be anything more than a systematic art or experimental doctrine ; and psychology not even this, but only a natural history of the inner sense or natural description of the soul. That which Kant's Metaphysical Elements of Natural Scierue, 1786 — in four chapters, Phoronomy, Dynamics, Mechanics, and Phe- nomenology — advances as pure physics or the metaphysics of corporeal na- ture, is a doctrine of motion. The fundamental determination of matter (of a somewhat which is to be the object of the external senses) is motion, for it is only through motion that these senses can be affected, and the understanding itself reduces all other predicates of matter to this. The second and most
