344 THE 'ORIGIN OF SPECIES.' [i860. 



I agree with your answer which you give to yourself on this 

 point ; and the simile of man now keeping down any new 

 man which might be developed, strikes me as good and new. 

 The white man is " improving off the face of the earth " even 

 races nearly his equals. With respect to islands, I think I would 

 trust to want of time alone, and not to bats and rodents. 



N.B. I know of no rodents on oceanic islands (except my 

 Galapagos mouse, which may have been introduced by man) 

 keeping down the development of other classes. Still much 

 more weight I should attribute to there being now, neither 

 in islands nor elsewhere, [any] known animals of a grade of 

 organisation intermediate between mammals, fish, reptiles, 

 &c, whence a new mammal could be developed. If every 

 vertebrate were destroyed throughout the world, except our 

 now well-established reptiles, millions of ages might elapse 

 before reptiles could become highly developed on a scale 

 equal to mammals ; and, on the principle of inheritance, 

 they would make some quite new class, and not mammals ; 

 though possibly more intellectual ! I have not an idea that 

 you will care for this letter, so speculative. 



Most truly yours, 



C. DARWIN. 



C. Darwin to Asa Gray. 



Down, Sept. 26 [1860]. 



.... I have had a letter of fourteen folio pages from 

 Harvey against my book, with some ingenious and new 

 remarks; but it is an extraordinary fact that he does not 

 understand at all what I mean by Natural Selection. I have 

 begged him to read the Dialogue in next ' Silliman/ as you 

 never touch the subject without making it clearer. I look at 

 it as even more extraordinary that you never say a word or 

 use an epithet which does not express fully my meaning. 

 Now Lyell, Hooker, and others, who perfectly understand my 



