| Both have the property in common of possessing an a priori origin; but, in the one, our knowledge is based upon conceptions, in the other, on the construction of conceptions. |
| Thus a decided dissimilarity between philosophical and mathematical cognition comes out--a dissimilarity which was always felt, but which could not be made distinct for want of an insight into the criteria of the difference. |
| And thus it happened that, as philosophers themselves failed in the proper development of the idea of their science, the elaboration of the science could not proceed with a definite aim, or under trustworthy guidance. |
| Thus, too, philosophers, ignorant of the path they ought to pursue and always disputing with each other regarding the discoveries which each asserted he had made, brought their science into disrepute with the rest of the world, and finally, even among themselves. |
| All pure a priori cognition forms, therefore, in view of the peculiar faculty which originates it, a peculiar and distinct unity; and metaphysic is the term applied to the philosophy which attempts to represent that cognition in this systematic unity. |
| The speculative part of metaphysic, which has especially appropriated this appellation--that which we have called the metaphysic of nature--and which considers everything, as it is (not as it ought to be), by means of a priori conceptions, is divided in the following manner. |
| Metaphysic, in the more limited acceptation of the term, consists of two parts--transcendental philosophy and the physiology of pure reason. |
| The former presents the system of all the conceptions and principles belonging to the understanding and the reason, and which relate to objects in general, but not to any particular given objects (Ontologia); the latter has nature for its subject-matter, that is, the sum of given objects--whether given to the senses, or, if we will, to some other kind of intuition--and is accordingly physiology, although only rationalis. |
| But the use of the faculty of reason in this rational mode of regarding nature is either physical or hyperphysical, or, more properly speaking, immanent or transcendent. |
| The former relates to nature, in so far as our knowledge regarding it may be applied in experience (in concreto); the latter to that connection of the objects of experience, which transcends all experience. |
| Transcendent physiology has, again, an internal and an external connection with its object, both, however, transcending possible experience; the former is the physiology of nature as a whole, or transcendental cognition of the world, the latter of the connection of the whole of nature with a being above nature, or transcendental cognition of God. |
| Immanent physiology, on the contrary, considers nature as the sum of all sensuous objects, consequently, as it is presented to us--but still according to a priori conditions, for it is under these alone that nature can be presented to our minds at all. |
| The objects of immanent physiology are of two kinds; 1. Those of the external senses, or corporeal nature; 2. The object of the internal sense, the soul, or, in accordance with our fundamental conceptions of it, thinking nature. |
| The metaphysics of corporeal nature is called physics; but, as it must contain only the principles of an a priori cognition of nature, we must term it rational physics. |
| The metaphysics of thinking nature is called psychology, and for the same reason is to be regarded as merely the rational cognition of the soul. |
| Thus the whole system of metaphysics consists of four principal parts: |
| 1. Ontology; 2. Rational Physiology; 3. Rational cosmology; and 4. Rational theology. |
| The second part--that of the rational doctrine of nature--may be subdivided into two, physica rationalis* and psychologia rationalis. |
| [*Footnote; It must not be supposed that I mean by this appellation what is generally called physica general is, and which is rather mathematics than a philosophy of nature. |
| For the metaphysic of nature is completely different from mathematics, nor is it so rich in results, although it is of great importance as a critical test of the application of pure understanding-cognition to nature. |
| For want of its guidance, even mathematicians, adopting certain common notions- which are, in fact, metaphysical--have unconsciously crowded their theories of nature with hypotheses, the fallacy of which becomes evident upon the application of the principles of this metaphysic, without detriment, however, to the employment of mathematics in this sphere of cognition.] |