DARWIN 315 



diate prompting cause of all those advances from 

 species to species which we have seen, upon other 

 grounds, to be necessarily supposed as having 

 taken place"; he continues that these ideas are 

 merely thrown out as hints toward the formation 

 of a just hypothesis which will come with ad- 

 vancing knowledge. He considers these natural 

 laws as instruments in working out and realizing 

 all the forms of being of the original Divine 

 Conception. 



These philosophic views were more definitely 

 expressed in the tenth edition, which appeared 

 in 1853. Here (p. 155) he gives as his final opin- 

 ion that the animal series is the result, first, of an 

 impulse, imparted by God, advancing all the 

 forms of life, through the various grades of or- 

 ganization, from the lowest to the highest plants 

 and animals; this is the Aristotehan 'internal 

 perfecting principle' somewhat modified by mod- 

 ern theology. As this first 'perfectmg' impulse 

 might manifestly produce types not at all fitted 

 to their environment, the author adds a second 

 impulse, tending to modify organic structures in 

 accordance with their environment, food, nature 

 of the habitat, and meteoric agencies, and thus 

 to produce the 'adaptations' of the natural phi- 

 losopher. 



This progressive advance of plants and ani- 

 mals with modification would also leave a gap at 



