THE MOTOR CENTERS AND THE WILL. 109 



ten you read, arranged schematically, the psychical processes, which, 

 for the sake of argument, we may assume are carried on by the mind 

 in these portions of the cortex, 



I wish to point out that we have structurally and physiologically 

 demonstrated with great probability the paths and centers of these 

 psychical actions. There is no break : the mere sight of an object 

 causes a stream of energy to travel through our sense areas, expand- 

 ing as it goes by following the widening sensory paths here repre- 

 sented, and at the same time we feel our intellect learns that new ideas 

 are rising up and finally expand into the process of deliberate thought, 

 concerning which all we know is from that treacherous support, name- 

 ly, introspection. 



Then come impulses to action, and these follow a converse path to 

 the receptive one just described ; the nerve-energy is concentrated 

 more and more until it culminates in the discharge of the motor cor- 

 puscles. We might represent the whole process of the voluntary act 

 by two fans side by side, and the illimitable space above their arcs 

 would serve very well to signify the darkness in which we sit con- 

 cerning the process of intellectual thought. 



What I have hastily sketched is the outline of the process of an 

 attentive or voluntary act. I say attentive advisedly, for I wish now 

 to put forward the view that the proper criterion of the voluntary 

 nature of an act is not the mere effort that is required to perform it, 

 but is the degree to ichich the attention is involved. The popular view 

 of the volitional character of an act being decided by the effort to keep 

 the action sustained is surely incomplete, for in the first place we are 

 not seeking to explain our consciousness of an effort ; we endeavor to 

 discover the causation of the effort. Our sense of effort only comes 

 when the will has acted, and that same sense is no doubt largely due 

 to the information which the struggling muscle sends to the brain, and 

 possibly is a conscious appreciation of how much energy this motor 

 corpuscle is giving out. 



Now, to give you an example. I see this tambour, and decide to 

 squeeze it, and do so. Now, this was a distinctly voluntary act ; but 

 the volitionary part of it was not the effort made, it was the deliber- 

 ate decision to cause the movement. I may now point out that in 

 this whole process we say, and say rightly, that our attention is in- 

 volved so long as we are deliberating over the object ; that as soon as 

 another object is brought to us our attention is distracted, that is to 

 say, turned aside. 



All writers are agreed that the attention can not be divided, that 

 we really only attend to one thing at once. It seems to me that this 

 is so obvious as not to require experimental demonstration ; but I 

 have led up to this point because I now wish to refer to the third part 

 of my subject, namely, the question as to whether we have a really 

 double nervous system or not. But, by way of preface, let me re- 



