222 THE METHOD OF DARWIN. 



after he had himself stated clearly its action 

 and results, there is no cause for wonder at his 

 not applying it to the derivation of species. 

 In fact, there was a good reason why he should 

 not do the latter. He expressed himself vigor- 

 ously in opposition to the belief that a species 

 can vary by an indefinite amount in any given 

 direction; and denied Condorcet's theory of 

 the indefinite perfectibility of the human race. 1 

 He admitted only a limited amount of varia- 

 tion within a species. Malthus. had worked out 

 the struggle for existence and recognized its 

 selective action, at least within a limited range; 

 and as a natural theologian he must have been 

 acquainted with numerous adaptations. But 

 he did not connect them as cause and effect, 

 because he did not admit general variability 

 of species, without which there could be no 

 material for the cause to act upon. 



When the work of Malthus fell into Darwin's 

 hands, the latter was in possession of the doc- 

 trine of descent, and many facts in harmony 

 with it, and hence the convi.ction in his mind 

 that there was an efficient cause for these facts. 

 The adaptations found in nature seemed the 

 most difficult facts to explain under the theory 

 of descent, and Darwin was already widely 



1 Principle of Population, p 270. 



