134 E VOL UTION AND DOGMA . 



Probability of Evolution. 



Such, then, in brief, is the argument in favor of 

 Evolution from classification, morphology, embry- 

 ology, geographical distribution and geological suc- 

 cession. The argument, as based on any one of 

 these four classes of facts, is strong, and to many, 

 if not most contemporary naturalists, conclusive. 

 But when we consider the joint effect of the argu- 

 ment built on the four classes of facts, and note in 

 detail the perfect harmony, the argument becomes 

 still stronger and, to all appearances, irrefragable. 

 The evidence furnished by one class of facts corrob- 

 orates and explains those offered by the others, and 

 thus the cumulative force of the testimony, given by 

 all the four classes, renders the theory, to say the 

 least, in the highest degree probable. We may not 

 be prepared to admit that the theory has the force of a 

 demonstration. If it had, organic Evolution would 

 cease to be any longer a matter of scientific inquiry 

 and would at once become a matter of scientific fact. 



But although Evolution is but a theory, and not 

 a demonstration, a probability and not a certainty, 

 it nevertheless possesses for the working naturalist a 

 value that can be fully appreciated only by those 

 who have labored in the museum and in the labora- 

 tory. " Probability," Bishop Butler tells us, " is the 

 guide of life." It is no less truly the guide of sci- 

 ence, and a highly probable theory often contributes 

 as effectually towards the advancement of science 

 and the acquisition of truth as would a demon- 

 strated fact. 



