en. xvii.] SOCIOLOGY AND FREE-WILL. 177 



action which is attended by a conscious comparison of im 

 pressions, and which involves nutritive changes in the cere 

 brum or cerebellum, or in both. As we saw in the pre 

 ceding chapter, the sequence of actions upon impressions is 

 either reflex or instinctive, and in either case automatic, so 

 long as the nervous energy liberated by the impression is 

 instantly discharged through a completely permeable chan 

 nel or set of channels. But in those higher organisms in 

 which an immensely varied experience has established innu 

 merable complex systems of less permeable channels, there 

 intervenes between the liberation of energy in the brain and 

 its discharge upon the motor centres a period during which 

 there is a tension between various nerve- currents, each seek 

 ing to discharge itself along the most permeable lines of 

 transit. We saw also that this period of tension is a period 

 of conscious deliberation, involving conscious reflection, and 

 feelings of desire or aversion. And these views turned out 

 to be justified by the fact that as soon as the frequent repeti 

 tion of any given set of experiences has rendered all the 

 transit-lines involved in the case completely permeable, so 

 that there is no longer any appreciable period of tension, 

 then the acts once conscious and voluntary become invo 

 luntary and automatic. 



Now the state of consciousness called Desire is accom 

 panied by a nascent excitement of the nerve-fibres distributed 

 upon the muscular apparatus whose activity is requisite for 

 the attainment of the desired object. There is a tendency to 

 go through with the movements needful for realizing the 

 desire ; and this tendency, unless neutralized by an an 

 tagonist tendency, must end in action. In the language of 

 dynamics, tension when not counteracted by opposing 

 tension, must pass into vis viva. This passage of nervous 

 tension into nervous vis viva constitutes volition, which may 



VOL. H. H 



