GENERAL SUMMARY AND CONCLUDING REMARKS. 437 



facts and principles poured into it by the advance of many 

 sciences. 



Of course it is always easy to withhold assent from a 

 probability, however strong : ** My belief," it may be said, " is 

 not to be wooed ; it shall only be compelled." Indeed, a man 

 may even pride himself on the severity of his requirements in 

 this respect ; and in popular writings we often find it taken 

 for granted that any scientific doctrine is then only entitled 

 to be regarded as scientific when it has been demonstrated. 

 But in science, as in other things, belief ought to be pro- 

 portionate to evidence ; and although for this very reason we 

 should ever strive for the attainment of better evidence, 

 scientific caution of such a kind must not be confused with a 

 merely ignorant demand for impossible evidence. Actually to 

 demonstrate the transition from non-conceptual to conceptual 

 ideation in the race, as it is every day demonstrated in the 

 individual, would plainly require the impossible condition 

 that conceptual thought should have observed its own origin. 

 To demand any demonstrative proof of the transition in the 

 race w^ould therefore be antecedently absurd. But if, as 

 Bishop Butler says, "probability is the very guide of life," 

 assuredly no less is it the very guide of science ; and here, I 

 submit, we are in the presence of a probability so irresistible 

 that to withhold from it the embrace of conviction would be 

 no longer indicative of scientific caution, but of scientific 

 incapacity. For if, as I am assuming, we already accept the 

 theory of evolution as applicable throughout the length and 

 breadth of the realm organic, it appears to me that we have 

 positively better reasons for accepting it as applicable to the 

 length and breadth of the realm mental. In other words, 

 looking to all that has now been said, I cannot help feeling 

 that there is actually better evidence of a psychological 

 transition from the brute to the man, than there is of a 

 morphological transition from one organic form to another, in 

 any of the still numerous instances where the intermediate 

 links do not happen to have been preserved. Thus, for 

 example, in my opinion an evolutionist of to-day who seeks to 



