vi CONCERNING NECESSARY TRUTHS 151 



are merely animal, and from which we can, d priori, draw no 

 inference, we are apt to transfer to inanimate objects, and to 

 suppose that they have some such feelings whenever they 

 transfer or receive motion." (IV. p. 91, note.) 



It is obviously, however, an absurdity not less 

 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, be- 

 cause, when we ourselves act as causes, or in voli- 

 tion, 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. 



