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[1] and psychologia rationalis.
The fundamental idea of a philosophy of pure reason of necessity dictates this division; it is, therefore, architectonical—in accordance with the highest aims of reason, and not merely technical, or according to certain accidentally-observed similarities existing between the different parts of the whole science. For this reason, also, is the division immutable and of legislative authority. But the reader may observe in it a few points to which he ought to demur, and which may weaken his conviction of its truth and legitimacy.
In the first place, how can I desire an
- ↑ 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.
