Ixvi INTRODUCTION 



to the fancy of the inventor. There is no longer any reason 

 to doubt that physiological processes are exclusively material, 

 like all other processes in the universe ; and that there exists 

 no independent entity of this character, as was assumed in 

 times of ignorance. Nevertheless, so highly complex is the 

 subject, and so pressing is the demand for some immediate 

 explanation, that there are still a few physiologists remaining 

 who invoke spirits to assist them in accounting for certain 

 phenomena that have yet been scarcely reached by the 

 rising tide of materialistic science. It is true that they are 

 not often rash enough to invoke an actual spiritual sub- 

 stance. They prefer to speak of " biotic energy " or " vital 

 force " : that is to say, they invent a spiritual form of 

 energy, rather than a spiritual form of substance. But 

 there is no essential difference whatever between the two.^ 

 If they affirm the existence of any kind of vital or spiritual 

 force, of non-material character, they are inexorably com- 

 mitted to a belief in souls or some such spiritual bodies. 

 Notwithstanding their protestations to the contrary, they 

 have no logical escape from the position. These physio- 

 logists urge vitalism almost exclusively on the grounds that, 

 without the assumption of a vital force, it is impossible to 

 explain certain of the more complex manifestations of 

 intelligence, voluntary movement, choice, etc. Now it is 

 but a short time back that even quite simple nervous pro- 

 cesses, such as reflex action, were impossible to explain by 

 mechanical or physico-chemical methods. It is now known 

 that these simple processes are in point of fact of a purely 

 mechanical nature ; and it is also very widely believed by 

 the great majority of physiologists that the more complex 

 cerebral operations are based entirely upon the reflex prin- 

 ciple, and indeed are nothing more than reflex action, 

 multipUed and compounded to a high degree of complexity. 

 So far then from there being any apparent impossibility 

 about explaining the highest mental manifestations on 



^ On this point, v. my article in Bedrock for October, 1912, with the ensuing con- 

 troversy. 



