THE SPECIES 267 



This theory rules out the possibiHty of the forming of 

 new genes — which has certainly not been proved ; but just 

 on that account it is remarkably simple and clear. It transfers 

 the centre of gravity from the material into the plan of Nature, 

 and thereby pushes the limits of the investigable as far back 

 as possible, to the limits, namely, of what human knowledge 

 can reach. Knowledge of conformity with plan belongs to 

 the capacities of our apperception ; and beyond the limits set 

 by that it is impossible to know anything. 



The special advantage of this theory, I consider, lies in 

 its putting aside the utterly impossible idea of each species 

 or genus having sprung from one pair of ancestors ; for it 

 is quite out of the question that one pair should contain all 

 the genes forming the genotype of the species or of the genus. 



To assume that the shaping of animals advances in accord- 

 ance with plan certainly gives a more solid foundation from 

 which to consider Nature than does the so-called evolutionary 

 idea, which is really just a misconception. And we can put 

 the more confidence in the idea, since, by amplifying the 

 melody " man," it leads us forward towards ages far richer 

 in possibilities than those offered by the physical forces, 

 which at any moment may induce a degeneration of the 

 creature that has been formed. 



Lastly, through the idea of shaping melodies that progress 

 step by step, we come to understand why it is, for instance, 

 that mammals still show rudiments of gill-arches. In fishes 

 these structures become gills, whereas in mammals quite 

 different organs are produced, for the development of which 

 the rudiment of the gill-arches seems to us a " detour." 



The melody " mammal " did not arise all by itself, but 

 at a certain point branched off from the melody " fish." 

 This certainly proves that mammals are related to fishes, 

 but not that mammals ever bore gills. If we ask whether 

 we ought to regard fishes as the ancestors of mammals, we 



