256 THE FOUNDATIONS OF ZOOLOGY 



" Far from imagining that cats exist in order to catch mice 

 well, Darwinism supposes that cats exist because they catch mice 

 well, mousing being not the end but the condition of their 

 existence." 



If this were all the difficulty natural selection puts in the way 

 of the argument from contrivance, I cannot believe Paley would 

 have found it serious ; for it is obvious that " it is not necessary 

 that a machine be perfect in order to show with what design it 

 was made " ; and I imagine Paley's answer to Huxley would be 

 that, whether the cat exists for catching mice or because of catch- 

 ing mice, the adjustment between its mechanism and the life of 

 mice is as real as the adjustment between the movements of the 

 watch and the movements of the earth, and as useful to cats as 

 watches are to those who make and buy them ; although we must 

 not forget to consider cats from the standpoint of the mouse. 



Darwin's objection to Paley's argument has recently been de- 

 veloped, at greater length, by Romanes, who holds that while the 

 origin of species by gradual development does not in itself affect 

 the argument from contrivance, it does so, when contrasted with 

 belief in special creation, because it reveals the possibility that 

 structures like the human eye may have been proximately due to 

 the operation of physical causes, whereas this possibility is ex- 

 cluded by the hypothesis of sudden or special creation. 



If the eye, as we find it in man, owes its origin to the slow 

 and gradual centralization and specialization, by natural selection, 

 of a vague sensibility to light, which was originally diffused over 

 the whole surface of the body, it follows "that each step in the 

 prolonged and gradual development of the eye was brought about 

 by the elimination of all the less adapted structures in any given 

 generation, i.e. the selection of all the better adapted to perpetuate 

 the improvement by heredity." 



"Will the teleologist," asks Romanes, "maintain that this selec- 

 tive process is itself indicative of special design ? If so, it appears 

 to me," he says, "that he is logically bound to maintain that the 

 little veins of colored sand, and of fragments of shells which we 

 so often find on the seashore, separated out from the acres of 

 yellow sand and brought together by the selective action of grav- 

 ity, are all equally indicative of special design." " The general 



