LIFE OF JAMES DWIGHT DANA 



" In your idea of species as specific amount or kind of 

 concentrated force, you fall back upon the broadest and 

 most fundamental views, and develop it, it seems to me, 

 with great ability and cogency. 



" Taking the cue of species, if I may so say, from the 

 inorganic, you develop the subject to great advantage 

 from your view, and all you say must have great weight, 

 in ' reasoning from the general/ But in reasoning from 

 inorganic species to organic species, and making it tell 

 where you want it and for what you want it to tell, you 

 must be sure that you are using the word ' species ' in 

 the same sense in the two, that the one is really an 

 equivalent of the other. That is what I am not convinced 

 of. And so to me the argument comes only with the 

 force of an analogy, whereas I suppose you want it to 

 come as demonstration. Very likely you could convince 

 me that there is no fallacy in reasoning from the one to 

 the other to the extent you do. But all my experience 

 makes me cautious and slow about building too much 

 upon analogies; and until I see further and clearer I 

 must continue to think that there is an essential difference 

 between kinds of animals or plants and kinds of matter. 

 How far we may safely reason from the one to the other 

 is the question. If we may go so even as far as you go, 

 might not Agassiz (at least plausibly) say that, as the 

 species Iron was created in a vast number of individuals 

 over the whole earth, so the presumption is that any 

 given species of plants or animals was originated in as 

 many individuals as there are now, and over as wide an 

 area, the human species under as great diversities as it 

 now has (barring historical intermixture) ? so reducing the 

 question between you to insignificance, because then the 

 question whether men are of one or of several species would 

 no longer be a question of fact, or of much consequence. 



' You can answer him from another starting-point, no 

 doubt ; but he may still insist that it is a legitimate carry- 

 ing out of your own principle. . . . 



' The tendency of my mind is opposed to this sort of 

 view; but you may be sure that before long there must 

 be one or more resurrections of the development theory 

 in a new form, obviating many of the arguments against 

 it, and presenting a more respectable and more formidable 

 appearance than it ever has before. . , . 



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