ON THE ORIGIN OF FOECE. 461 



large classes of phenomena, and those most important 

 ones, which, we are quite sure, take place in virtue of 

 such volitions, and without which we are equally sure 

 they would not take place at all. In that peculiar 

 mental sensation, clear to the apprehension of every one 

 who has ever performed a voluntary act, which is present 

 at the instant when the determination to do a thing is 

 carried out into the act of doing it (a sensation which, 

 in default of a term more specifically appropriated to it, 

 we may call that of effort) we have a consciousness of 

 immediate and personal causation which cannot be dis- 

 puted or ignored. And when we see the same kind of act 

 performed by another, we never hesitate in assuming for 

 him that consciousness which we recognize in ourselves : 

 and in this case we can verify our conclusion by oral 

 communication. The first step in the way of generaliza- 

 tion thus taken, the next is obvious enough. Though a 

 flight rather than a step, it forces itself on our thoughts with 

 ever-increasing cogency, the more it is dwelt upon, and 

 the more utterly abortive all attempt to render any other 

 account of that deep mystery of nature mechanical 

 force is found to be. f Whenever, in the material world, 

 what we call a phsenomenon or an event takes place, we 

 either find it resolvable ultimately into some change of 

 place or of movement in material substance, or we en- 

 deavour to trace it up to some such change ; and only 

 when successful in such endeavour we consider that we 

 have arrived at its theory. In every such change we re- 

 cognize the action of FORCE. And in the only case in 

 which we are admitted into any personal knowledge of 



