It is therefore rational, even meritorious, to pursue natural mechanism, in respect of the explanation of natural products, so far as can be done with probability; and if we give up the attempt it is not because it is impossible _in itself_ to meet in this path with the purposiveness of nature, but only because it is impossible _for us_ as men. For there would be required for that an intuition other than sensuous, and a determinate knowledge of the intelligible substrate of nature from which a ground could be assigned for the mechanism of phenomena according to particular laws, which quite surpasses our faculties. Hence if the naturalist would not waste his labour he must in judging of things, the concept of any of which is indubitably established as a natural purpose (organised beings), always lay down as basis an original organisation, which uses that very mechanism in order to produce fresh organised forms or to develop the existing ones into new shapes (which, however, always result from that purpose and conformably to it). It is praiseworthy by the aid of comparative anatomy to go through the great creation of organised natures, in order to see whether there may not be in it something similar to a system and also in accordance with the principle of production. For otherwise we should have to be content with the mere principle of judgement (which gives no insight into their production) and, discouraged, to give up all claim to _natural insight_ in this field. The agreement of so many genera of animals in a certain common schema, which appears to be fundamental not only in the structure of their bones but also in the disposition of their remaining parts,--so that with an admirable simplicity of original outline, a great variety of species has been produced by the shortening of one member and the lengthening of another, the involution of this part and the evolution of that,--allows a ray of hope, however faint, to penetrate into our minds, that here something may be accomplished by the aid of the principle of the mechanism of nature (without which there can be no natural science in general). This analogy of forms, which with all their differences seem to have been produced according to a common original type, strengthens our suspicions of an actual relationship between them in their production from a common parent, through the gradual approximation of one animal-genus to another--from those in which the principle of purposes seems to be best authenticated, _i.e._ from man, down to the polype, and again from this down to mosses and lichens, and finally to the lowest stage of nature noticeable by us, viz. to crude matter. And so the whole Technic of nature, which is so incomprehensible to us in organised beings that we believe ourselves compelled to think a different principle for it, seems to be derived from matter and its powers according to mechanical laws (like those by which it works in the formation of crystals).