ii8 THE GRAMMAR OF SCIENCE 



produce the destruction of the window is, I think, the idea 

 involved in thus speaking of the moving stone as the 

 cause of the breakage. But were our perceptive organs 

 sufficiently powerful, science conceives that we should see 

 before the impact particles of window and particles of 

 stone moving in a certain manner, and after the impact the 

 same particles moving in a very different manner. We 

 might carefully describe these motions, but we should be un- 

 able to say why one stage would follow another, just as we can 

 describe how a stone falls to the earth, but not say why it does. 

 Thus, scientifically the idea of necessity in the stages of 

 the sequence — stone in motion, broken window — or the 

 idea of enforcement would disappear ; we should have a 

 routine of experience, but an unexplained routine. When 

 we speak, however, of the stages of a sequence in ordinary 

 life as causes, I do not think it is because we are approach- 

 ing the scientific standpoint, but I fear it arises from our 

 associating, through long usage, the idea oi force with the 

 stone. The stone is the cause of certain new m^otions, 

 just as I am looked upon as the cause of certain motions 

 in the stone — that is, both stone and I are supposed to 

 enforce subsequent stages in the sequence. Now the 

 reader who has once dismissed the notion of force as a 

 cause, which I think he will probably be prepared to do, 

 will perhaps admit that there is no element of enforce- 

 ment, but merely a routine of experience in the motions 

 of particles of stone and glass. Still he may say that the 

 will of a living agent does seem to him a cause of motion 

 in the necessarian sense. Nor would he be in this un- 

 reasonable, for I must confess that to attribute sequences 

 of motion to will seems at first sight a more scientific 

 hypothesis than to attribute them to an unknown and 

 possibly unknowable source force. 



§ 3. — Will as a Cause 



It is not unnatural that human beings should be 

 impressed at a very early stage of their mental growth 

 with the real, or at any rate apparent, power which lies in 



