92 CHARLES DARWIN 



fuller's teasel is a sport of the wild form, with curved 

 hooks specially adapted by a freak of nature for the 

 teasing of wool. So in every case man, by deliberately 

 picking out for breeding or seeding purposes the acci- 

 dental variations which happened best to suit his own 

 needs, has succeeded at last in producing races admirably 

 fitted in the minutest particulars for the special func- 

 tions to which they are applied. There appears indeed 

 to be hardly any limit to the almost infinite plasticity 

 and modifiability of domestic animals. * It would seem,' 

 said a great sheep-breeder, speaking of sheep, *' as if 

 farmers had chalked out upon a wall a form perfect in 

 itself, and then proceeded to give it existence/ 



Now, what is thus true within narrow limits, and in 

 a short space of time about the deliberate action of 

 man, Darwin showed to be also true within wider limits 

 and spread over longer geological epochs about the un- 

 conscious action of nature. And herein consisted his 

 great advance upon the earlier evolutionism of Lamarck, 

 Goethe, and Erasmus Darwin. For while these instinc- 

 tive pioneers of the evolutionary spirit saw clearly that 

 animals and plants betrayed signs of common descent 

 from one or a lew original ancestors, they did not see 

 what was the mechanism by which such organisms had 

 been differentiated into so many distinct genera and 

 species. They caught, indeed, at the analogy of varia- 

 tion under domestication and in the wild state, but they 

 missed the subtler and deeper analogy between human 

 and natural selection. Now, variation alone would give 

 us a world consisting not of definite kinds fairly well 

 demarcated one from the other, but of innumerable un- 

 classified and unorganisable individuals, all shading off 



