To this highest standpoint I am conducted by the law of homogeneity, as to all lower and more variously-determined conceptions by the law of specification.Now as in this way there exists no void in the whole extent of all possible conceptions, and as out of the sphere of these the mind can discover nothing, there arises from the presupposition of the universal horizon above mentioned, and its complete division, the principle: Non datur vacuum formarum.This principle asserts that there are not different primitive and highest genera, which stand isolated, so to speak, from each other, but all the various genera are mere divisions and limitations of one highest and universal genus; and hence follows immediately the principle:
Datur continuum formarum.This principle indicates that all differences of species limit each other, and do not admit of transition from one to another by a saltus, but only through smaller degrees of the difference between the one species and the other.In one word, there are no species or sub-species which (in the view of reason) are the nearest possible to each other; intermediate species or sub-species being always possible, the difference of which from each of the former is always smaller than the difference existing between these.
The first law, therefore, directs us to avoid the notion that there exist different primal genera, and enounces the fact of perfect homogeneity; the second imposes a check upon this tendency to unity and prescribes the distinction of sub-species, before proceeding to apply our general conceptions to individuals.The third unites both the former, by enouncing the fact of homogeneity as existing even in the most various diversity, by means of the gradual transition from one species to another.Thus it indicates a relationship between the different branches or species, in so far as they all spring from the same stem.
But this logical law of the continuum specierum (formarum logicarum)presupposes a transcendental principle (lex continui in natura), without which the understanding might be led into error, by following the guidance of the former, and thus perhaps pursuing a path contrary to that prescribed by nature.This law must, consequently, be based upon pure transcendental, and not upon empirical, considerations.For, in the latter case, it would come later than the system; whereas it is really itself the parent of all that is systematic in our cognition of nature.These principles are not mere hypotheses employed for the purpose of experimenting upon nature;although when any such connection is discovered, it forms a solid ground for regarding the hypothetical unity as valid in the sphere of nature- and thus they are in this respect not without their use.
But we go farther, and maintain that it is manifest that these principles of parsimony in fundamental causes, variety in effects, and affinity in phenomena, are in accordance both with reason and nature, and that they are not mere methods or plans devised for the purpose of assisting us in our observation of the external world.
But it is plain that this continuity of forms is a mere idea, to which no adequate object can be discovered in experience.And this for two reasons.First, because the species in nature are really divided, and hence form quanta discreta; and, if the gradual progression through their affinity were continuous, the intermediate members lying between two given species must be infinite in number, which is impossible.Secondly, because we cannot make any determinate empirical use of this law, inasmuch as it does not present us with any criterion of affinity which could aid us in determining how far we ought to pursue the graduation of differences: it merely contains a general indication that it is our duty to seek for and, if possible, to discover them.
When we arrange these principles of systematic unity in the order conformable to their employment in experience, they will stand thus:
Variety, Affinity, Unity, each of them, as ideas, being taken in the highest degree of their completeness.Reason presupposes the existence of cognitions of the understanding, which have a direct relation to experience, and aims at the ideal unity of these cognitions- a unity which far transcends all experience or empirical notions.The affinity of the diverse, notwithstanding the differences existing between its parts, has a relation to things, but a still closer one to the mere properties and powers of things.For example, imperfect experience may represent the orbits of the planets as circular.But we discover variations from this course, and we proceed to suppose that the planets revolve in a path which, if not a circle, is of a character very similar to it.That is to say, the movements of those planets which do not form a circle will approximate more or less to the properties of a circle, and probably form an ellipse.The paths of comets exhibit still greater variations, for, so far as our observation extends, they do not return upon their own course in a circle or ellipse.But we proceed to the conjecture that comets describe a parabola, a figure which is closely allied to the ellipse.In fact, a parabola is merely an ellipse, with its longer axis produced to an indefinite extent.Thus these principles conduct us to a unity in the genera of the forms of these orbits, and, proceeding farther, to a unity as regards the cause of the motions of the heavenly bodies- that is, gravitation.But we go on extending our conquests over nature, and endeavour to explain all seeming deviations from these rules, and even make additions to our system which no experience can ever substantiate- for example, the theory, in affinity with that of ellipses, of hyperbolic paths of comets, pursuing which, these bodies leave our solar system and, passing from sun to sun, unite the most distant parts of the infinite universe, which is held together by the same moving power.
