150 HUME vi 



gross than that of supposing the sensation of 

 warmth to exist in a fire, to imagine that the sub- 

 jective sensation of effort, or resistance, in ourselves 

 can be present in external objects, when they stand 

 in the relation of causes to other objects. 



To the argument, that we have a right to sup- 

 pose the relation of cause and effect to contain 

 something more than invariable succession, because, 

 when we ourselves act as causes, or in volition, we 

 are conscious of exerting power; Hume replies, 

 that we know nothing of the feeling we call power 

 except as effort or resistance ; and that we have 

 not the slightest means of knowing whether it has 

 anything to do with the production of bodily 

 motion or mental changes. And he points out, 

 as Descartes and Spinoza had done before him, 

 that when voluntary motion takes place, that 

 which we will is not the immediate consequence 

 of the act of volition, but something which is 

 separated from it by a long chain of causes and 

 effects. If the will is the cause of the movement 

 of a limb, it can be so only in the sense that the 

 guard who gives the order to go on, is the cause 

 of the transport of a train from one station to 

 another. 



" We learn from anatomy, that the immediate object of power 

 in voluntary notion is not the member itself which is moved, 

 but certain muscles and nerves and animal spirits, and perhaps 

 something still more minute and unknown, through which the 

 motion is successively propagated, ere it reached the member 



