22 De Vi Physica 



ments to produce or explain. He treats 

 the ANIMAL precisely as if it were a ROCK, 

 capable of being arrived at by the accu- 

 mulation of minute increments in immense 

 periods of time. The essential difference be- 

 tween a living animal, and a dead mechanical 

 mass of matter, escaped his attention. The 

 false analogy of artificial selection led him 

 astray. He saw it producing great cumu- 

 lative effect by the addition of slight varia- 

 tions : but wholly failed to perceive two 

 things : I. That this addition depends on 

 the devices of art, and is impossible under 

 nature. II. That no organ has ever been 

 produced by artificial selection, which only 

 varies the form and size of those existing. 

 He most unaccountably overlooks a fact, 

 sufficiently obvious, that in the hands of 

 art, the animal has its life preserved for it, 

 under all its transmogrifications ; whereas 

 under Nature, it has to preserve its own. 



