2 6o LIFE AND HABIT. 



impossible to attribute the innumerable structures which 

 are so well adapted to the habits of life of each species 

 to unknown causes. 



" I can no more believe in this" continues Mr. Dar- 

 win, " than that the well-adapted form of a race-horse 

 or greyhound, which, before the principle of selection 

 by man was well understood, excited so much surprise 

 in the minds of the older naturalists, can thus be ex- 

 plained" ("Natural Selection," p. 171, ed. 1876). 



Or, in other words, " I can no more believe that the 

 well- adapted structures of species are due to unknown 

 causes, than I can believe that the well-adapted form 

 of a race-horse can be explained by being attributed to 

 unknown causes." 



I have puzzled over this paragraph for several hours 

 with the sincerest desire to get at the precise idea which 

 underlies it, but the more I have, studied it the more 

 convinced I am that it does not contain, or at any rate 

 convey, any clear or definite idea at all. If I thought 

 it was a mere slip, I should not call attention to it ; this 

 book will probably have slips enough of its own with- 

 out introducing those of a great man unnecessarily ; but 

 I I submit that it is necessary to call attention to it here, 

 inasmuch as it is impossible to believe that after years 

 of reflection upon his subject, Mr. Darwin should have 

 written as above, especially in such a place, if his mind 

 was really clear about his own position. Immediately 

 after the admission of a certain amount of miscalcula- 

 tion, there comes a more or less exculpatory sentence 

 which sounds so right that ninety-nine people out of a 

 hundred would walk through it, unless led by some 



