1873O Molecular Motion. 433 



particles ; but we are not concerned about the cause of the 

 motion, but about what directs that motion. 



When a molecule is to be moved, there is an infinite 

 number of directions in which force may be conceived to 

 move it. But out of the infinite number of different paths, 

 what is it that directs the force to select the right path ? 



Is it asserted that force is self-directing ? This is simply 

 getting into confusion again. What conceivable idea can 

 be attached to a self-directing force ? Is force a something 

 which not only acts but determines for itself how and when 

 it shall act ? In what conceivable way can force direct its 

 own path ? A molecule has to be moved into its proper 

 place in an organic form ; a force gives motion to the mole- 

 cule ; but out of the infinite number of possible directions 

 in which the molecule may be moved the force moves it in 

 the right direction. What is that something which thus 

 guides the force ? The force guides itself, it is replied. Be 

 it so ; but in what way does the force direct or guide itself? 

 What is the nature of that something in virtue of which 

 the force directs its actions ? Is it supposed that that 

 something belonging to the force which thus guides and 

 directs its action is itself a force ? Does the force direct 

 itself by means of a force ? if so, then we are back to our 

 old absurdity of a force determining a force. And if this 

 directing something is not a force, what is it ? But if this 

 something is not a force, it follows that there is something 

 else to be known than mere force before we can penetrate 

 the mystery of nature. 



The simple truth is, in attempting to account for the 

 determination of motion by referring it to a force, we are 

 attempting an absolute impossibility. The production of 

 motion and the determination of motion are two things 

 absolutely different in their essential nature. Force pro- 

 duces motion ; but it is as impossible that force can deter- 

 mine motion as that two can be equal to three, or that 

 a thing can be and not be at the same time. The necessity 

 is as absolute in the one case as in the other. 



If any one imagines that he can conceive motion as being 

 directed or determined by a force, he will find, on subjecting 

 his thoughts to a proper analysis, that the determination is 

 not due to the force which he imagines, but is due to the 

 direction in which his imagined force exerts itself. The 

 determination results not from his imagined force, but from 

 the way in which his. force acts. 



As the distinction between the production of motion and 

 its determination, or between the production of an act and 



