346 STUDIES, SCIENTIFIC AND SOCIAL chap. 



the effects of effort and desire leading to the development 

 of parts and organs calculated to gratify those desires. 

 The great French naturalists Geoffrey and Isidore St. 

 Hildaire adopted these views with certain modifications, as 

 did a limited number of German naturalists ; while they 

 were popularly set forth with much knowledge and 

 literary skill by the late Robert Chambers in his Vestiges 

 of Creation. Somewhat later the general theory of evolu- 

 tion was explained and illustrated by Herbert Spencer 

 with so much power and completeness as to compel its 

 acceptance by most thinkers ; but neither he, nor any of 

 the great writers who had gone before him, had been able 

 to overcome the difficulty of explaining the process of 

 organic evolution, since no one had been able to show how 

 the wonderful and complex adaptations of living things to 

 their environment could have been produced by means of 

 known laws and through causes proved to exist and to be 

 of sufficient potency. Alike for naturalists, for men of 

 science in general, and for students in philosophy, the 

 method of organic evolution remained an insoluble 

 problem. 



Darwin himself, who after his return from the Beagle 

 voyage was in close intimacy with the chief naturalists of 

 the day, tells us in his letters of the general feeling with 

 regard to all theories of the evolution of species. In 1844 

 he wrote to Dr. Hooker — " At last, gleams of light have 

 come, and I am almost convinced, that species are not (it 

 is like confessing a murder) immutable." And again in 

 1845 to L. Jenyns — " A long searching amongst agri- 

 cultural and horticultural books and people makes me 

 believe (I well know how absurdly presumptuous this must 

 appear) that I see the way in which new varieties become 

 exquisitely adapted to the external conditions of life and 

 to other surrounding beings. I am a bold man to lay 

 myself open to being thought a complete fool, and a most 

 deliberate one." 



Considering that this state of opinion prevailed up to 

 the very date of publication of the Origin of Species, the 

 effect produced by that work was certainly marvellous. 

 A considerable body of the more thoughtful naturalists at 

 once accepted it as affording, if not a complete solution. 



