262 THE HISTOEY OF CREATION. 



organic self-preservation of which Schiller, the idealist (not 

 Goethe, the realist ! ) says : 



" Meanwliile, until pldlosopliy 

 Sustains tlie structure of the world. 

 Her workings will be carried on 

 By hunger and by love."* 



It is these two powerful fundamental instincts which, by 

 their varying activity, produce such extraordinary differ- 

 ences in species through the struggle for life. They are 

 the foundations of the phenomena of Inheritance and 

 Adaptation. We have, in fact, traced all phenomena of 

 Inheritance to propagation, all phenomena of Adaptation to 

 nutrition, as the two wider classes of material phenomena 

 to which they belong. 



The struggle for life in natural selection acts with as 

 much selective power as does the will of man in artificial 

 selection. The latter, however, acts according to a plan and 

 consciously, the former without a plan and unconsciously. 

 This important difference between artificial and natural 

 selection deserves especial consideration. For we learn by 

 it to understand how arrangements serving a purpose 

 can he produced hy. mechanical causes acting without an 

 object, as well as hy causes acting for an ohject. The 

 products of natural selection are arranged even more for a 

 purpose than the artificial products of man, and yet they 

 owe their existence not to a creative power acting for a 

 definite purpose, but to a mechanical relation acting uncon- 



 " Einstweilen bis den Bau der Welt 

 Philosophie zusammenhalt, 

 Erhalt sich ihr Getriebe 

 Durch Hunger und durch Liebe. 



