WILL. 581 



only tiling to do is to make hypotheses, till we find some 

 which seem to cover all the facts. 



How is a fresh path ever formed ? All paths are paths 

 of discharge, and the discharge always takes place in the 

 direction of least resistance, whether the cell which dis- 

 charges be ' motor ' or ' sensory.' The connate paths of least 

 resistance are the paths of instinctive reaction ; and I sub- 

 mit as my first hypothesis that these paths all run one way, 

 that is from ^sensory ' cells into 'motor ' cells and from motor 

 cells into muscles, ivithout ever taking the reverse direction. A 

 motor cell, for example, never awakens a sensory cell di- 

 rectly, but only through the incoming current caused by 

 the bodily movements to which its discharge gives rise. 

 And a sensory cell alivays discharges or normally tends to 

 discharge towards the motor region. Let this direction be 

 called the 'forward ' direction. I call the law an hypothe- 

 sis, but really it is an indubitable truth. No impression 

 or idea of eye, ear, or skin comes to us without occasioning 

 a movement, even though the movement be no more than 

 the accommodation of the sense-organ ; and all our trains 

 of sensation and sensational imagery have their terms 

 alternated and interpenetrated with motor processes, of most 

 of which we practically are unconscious. Another way of 

 stating the rule is to say that, primarily or connately, all 

 currents through the brain run towards the Rolandic re- 

 gion, and that there they run out, and never return upon 

 themselves. From this point of view the distinction of 

 sensory and motor cells has no fundamental significance. 

 All cells are motor ; we simply call those of the Rolandic 

 region, those nearest the mouth of the funnel, the motor 

 cello par excellence. 



A corollary of this law is that ' sensory ' cells do not 

 awaken each other connately ; that is, that no one sensi- 

 ble property of things has any tendency, in advance of 

 experience, to awaken in us the idea of any other sen- 

 sible properties which in the nature of things may go 

 with it. There is no a priori calling up of one * idea ' by an- 

 other ; the only a priori couplings are of ideas with move- 

 ments. All suggestions of one sensible fact by another 



