' THE ORIGIN OF SPECIES ' 93 



indefinitely one into the other, and incapable of being 

 reduced by human ingenuity to any orderly hierarchical 

 system. Furthermore, it would give us creatures with- 

 out special adaptation of any kind to the peculiar cir- 

 cumstances of their own environment. To account for 

 adaptation, for the almost perfect fitness of every 

 plant and every animal to its position in life, for the 

 existence (in other words) of definitely correlated parts 

 and organs, we must call in the aid of survival of the 

 fittest. Without that potent selective agent, our con- 

 ception of the becoming of life is a mere chaos ; order 

 and organisation are utterly inexplicable save by the 

 brilliant illuminating ray of the Darwinian principle. 

 That is why Darwin destroyed at one blow the specious 

 arguments of the early teleologists ; he showed that 

 where Chambers and even Erasmus Darwin had seen 

 the working of a final cause, we ought rather to recog- 

 nise the working of an efficient cause, whose outcome 

 necessarily but fallaciously simulates the supposed fea- 

 tures of an a priori finality. 



From art, then, Darwin harks back once more to 

 nature. He proceeds to show that variability occurs 

 among all wild plants and animals, though not so fre- 

 quently under ordinary circumstances as in the case of 

 domesticated species. Individual differences everywhere 

 occur between plant and plant, between animal and 

 animal. Sometimes these differences are so very 

 numerous that it is impossible to divide the individuals 

 at all into well-marked kinds ; for example, among 

 British wild-roses, brambles, hawkweeds and epilobes, 

 with a few other very variable families, Babington 

 makes as many as 251 distinct species, where Bentham 



