116 CHARLES DARWIN. 



This metaphor forms an important part of the 

 conclusion of $ie work in question ("Variation of 

 Animals and Plants," etc.) : 



" The long-continued accumulation of beneficial variations 

 will infallibly have led to structures as diversified, as beauti- 

 fully adapted for various purposes and as excellently co- 

 ordinated, as we see in the animals and plants around us. 

 Hence I have spoken of selection as the paramount power, 

 whether applied by man to the formation of domestic breeds, 

 or by nature to the production of species. I may recur to the 

 metaphor given in a former chapter : if an architect were to 

 rear a noble and commodious edifice, without the use of cut 

 stone, by selecting from the fragments at the base of a precipice 

 wedged-formed stones for his arches, elongated stones for his 

 lintels, and flat stones for his roof, we should admire his skill 

 and regard him as the paramount power. Now, the fragments 

 of stone, though indispensable to the architect, bear to the edifice 

 built by him the same relation which the fluctuating variations 

 of organic beings bear to the varied and admirable structures 

 ultimately acquired by their modified descendants. 



"Some authors have declared that natural selection ex- 

 plains nothing, unless the precise cause of each slight individual 

 difference be made clear. If it were explained to a savage 

 utterly ignorant of the art of building, how the edifice had 

 been raised stone upon stone, and why wedge-formed fragments 

 were used for the arches, flat stones for the roof, &c. ; and if 

 the use of each part and of the whole building were pointed 

 out, it would be unreasonable if he declared that nothing had 

 been made clear to him, because the precise cause of the shape 

 of each fragment could not, be told. But this is a nearly 

 parallel case with the objection that selection explains 

 nothing, because we know not the cause of each individual 

 difference in the structure of each being." 



" The shape of the fragments of stone at the base of our 

 precipice may be called accidental, but this is not strictly 

 correct ; for the shape of each depends on a long sequence of 

 events, all obeying natural laws. . . . But in regard to the 



