2IO SPREAD OF EVOLUTION. [1863 



P.S. In fact, the belief in Natural Selection must at pres- 

 ent be grounded entirely on general considerations, (i) On 

 its being a vera causa, from the struggle for existence ; and 

 the certain geological fact that species do somehow change. 

 (2) From the analogy of change under domestication by 

 man's selection. (3) And chiefly from this view connecting 

 under an intelligible point of view a host of facts. When we 

 descend to details, we can prove that no one species has 

 changed [/. e. we cannot prove that a single species has 

 changed] ; nor can we prove that the supposed changes are 

 beneficial, which is the groundwork of the theory. Nor can 

 we explain why some species have changed and others have 

 not. The latter case seems to me hardly more difficult to 

 understand precisely and in detail than the former case of 

 supposed change. Bronn may ask in vain, the old creationist 

 school and the new school, why one mouse has longer ears 

 than another mouse, and one plant more pointed leaves than 

 another plant. 



C. Darwin to G. Bentham. 



Down, June 19 [1863]. 



MY DEAR BENTHAM, I have been extremely much pleased 

 and interested by your address, which you kindly sent me. 

 It seems to be excellently done, with as much judicial calm- 

 ness and impartiality as the Lord Chancellor could have 

 shown. But whether the " immutable " gentlemen would 

 agree with the impartiality may be doubted, there is too much 

 kindness shown towards me, Hooker, and others, they might 

 say. Moreover I verily believe that your address, written as 

 it is, will do more to shake the unshaken and bring on those 

 leaning to our side, than anything written directly in favor of 

 transmutation. I can hardly tell why it is, but your address 

 has pleased me as much as Lyell's book disappointed me, 

 that is, the part on species, though so cleverly written. I 

 agree with all your remarks on the reviewers. By the way, 

 Lecoq * is a believer in the change of species. I, for one, can 



* Author of ' Geographic Botanique.' 9 vols. 1854-58. 



