236 SELECTION. Chap. XXI. 



Throughout this chapter and elsewhere I have spoken of 

 selection as the paramount power, yet its action absolutely 

 depends on what we in our ignorance call spontaneous or 

 accidental variability. Let an architect be compelled to 

 build an edifice with uncut stones, fallen from a precipice. 

 The shape of each fragment may be called accidental ; yet 

 the shape of each has been determined by the force of gravity, 

 the nature of the rock, and the slope of the precipice, — events 

 and circumstances, all of which depend on natural laws ; but 

 there is no relation between these laws and the purpose for 

 which each fragment is used by the builder. In the same 

 manner the variations of each creature are determined by 

 fixed and immutable laws ; but these bear no relation to the 

 living structure which is slowly built up through the power 

 of selection, whether this be natural or artificial selection. 



If our architect succeeded in rearing a noble edifice, using 

 the rough wedge-shaped fragments for the arches, the longer 

 stones for the lintels, and so forth, we should admire his skill 

 even in a higher degree than if he had used stones shaped for 

 the purpose. So it is with selection, whether applied by 

 man or by nature ; for although variability is indispensably 

 necessary, yet, when we look at some highly complex and 

 excellently adapted organism, variability sinks to a quite 

 subordinate position in importance in comparison with selec- 

 tion, in the same manner as the shape of each fragment used 

 by our supposed architect is unimportant in comparison with 

 his skill. 





