| The logical principle of genera, which demands identity in phenomena, is balanced by another principle--that of species, which requires variety and diversity in things, notwithstanding their accordance in the same genus, and directs the understanding to attend to the one no less than to the other. |
| This principle (of the faculty of distinction) acts as a check upon the reason and reason exhibits in this respect a double and conflicting interest--on the one hand, the interest in the extent (the interest of generality) in relation to genera; on the other, that of the content (the interest of individuality) in relation to the variety of species. |
| In the former case, the understanding cogitates more under its conceptions, in the latter it cogitates more in them. |
| This distinction manifests itself likewise in the habits of thought peculiar to natural philosophers, some of whom--the remarkably speculative heads--may be said to be hostile to heterogeneity in phenomena, and have their eyes always fixed on the unity of genera, while others--with a strong empirical tendency--aim unceasingly at the analysis of phenomena, and almost destroy in us the hope of ever being able to estimate the character of these according to general principles. |
| The latter mode of thought is evidently based upon a logical principle, the aim of which is the systematic completeness of all cognitions. |
| This principle authorizes me, beginning at the genus, to descend to the various and diverse contained under it; and in this way extension, as in the former case unity, is assured to the system. |
| For if we merely examine the sphere of the conception which indicates a genus, we cannot discover how far it is possible to proceed in the division of that sphere; just as it is impossible, from the consideration of the space occupied by matter, to determine how far we can proceed in the division of it. |
| Hence every genus must contain different species, and these again different subspecies; and as each of the latter must itself contain a sphere (must be of a certain extent, as a conceptus communis), reason demands that no species or sub-species is to be considered as the lowest possible. |
| For a species or sub-species, being always a conception, which contains only what is common to a number of different things, does not completely determine any individual thing, or relate immediately to it, and must consequently contain other conceptions, that is, other sub-species under it. |
| This law of specification may be thus expressed; entium varietates non temere sunt minuendae. |
| But it is easy to see that this logical law would likewise be without sense or application, were it not based upon a transcendental law of specification, which certainly does not require that the differences existing phenomena should be infinite in number, for the logical principle, which merely maintains the indeterminateness of the logical sphere of a conception, in relation to its possible division, does not authorize this statement; while it does impose upon the understanding the duty of searching for subspecies to every species, and minor differences in every difference. |
| For, were there no lower conceptions, neither could there be any higher. |
| Now the understanding cognizes only by means of conceptions; consequently, how far soever it may proceed in division, never by mere intuition, but always by lower and lower conceptions. |
| The cognition of phenomena in their complete determination (which is possible only by means of the understanding) requires an unceasingly continued specification of conceptions, and a progression to ever smaller differences, of which abstraction bad been made in the conception of the species, and still more in that of the genus. |
| This law of specification cannot be deduced from experience; it can never present us with a principle of so universal an application. |
| Empirical specification very soon stops in its distinction of diversities, and requires the guidance of the transcendental law, as a principle of the reason--a law which imposes on us the necessity of never ceasing in our search for differences, even although these may not present themselves to the senses. |
| That absorbent earths are of different kinds could only be discovered by obeying the anticipatory law of reason, which imposes upon the understanding the task of discovering the differences existing between these earths, and supposes that nature is richer in substances than our senses would indicate. |
| The faculty of the understanding belongs to us just as much under the presupposition of differences in the objects of nature, as under the condition that these objects are homogeneous, because we could not possess conceptions, nor make any use of our understanding, were not the phenomena included under these conceptions in some respects dissimilar, as well as similar, in their character. |
| Reason thus prepares the sphere of the understanding for the operations of this faculty; 1. By the principle of the homogeneity of the diverse in higher genera; 2. By the principle of the variety of the homogeneous in lower species; and, to complete the systematic unity, it adds, 3. A law of the affinity of all conceptions which prescribes a continuous transition from one species to every other by the gradual increase of diversity. |
| We may term these the principles of the homogeneity, the specification, and the continuity of forms. |
| The latter results from the union of the two former, inasmuch as we regard the systematic connection as complete in thought, in the ascent to higher genera, as well as in the descent to lower species. |