the Fundamental Problem of Nature. 5 



the Determination of the motion. It must be evident to every 

 one who will consider the matter that these two things are 

 radically distinct. And they are not only radically distinct, 

 but must be separately accounted for. To account for the 

 mere existence of motion, does not account for its happening in 

 one way rather than in some other. It is quite true that the 

 one cannot be produced without the other; we cannot deter- 

 mine motion unless there is motion to be determined ; we cannot 

 determine that which has got no existence ; neither, on the 

 other hand, can w^e produce motion without at the same time 

 giving; it some particular determination in regard to time, place, 

 or other circumstance. But, although the one cannot be pro- 

 duced without the other, yet they are the result of different agen- 

 cies ; and to assign a sufficient cause for the one does not in the 

 least degree satisfy the mind as to the presence of the other. 

 To account for the motion of a ball does not account for why it 

 moves, say, east rather than west or in any other possible dn-ec- 

 tion. A force, it is true, cannot act without at the same time 

 acting in some particular way, nor move a body without moving 

 it in some particular direction ; but to account for the one does 

 not satisfy the mind in regard to the other. The explosion of 

 the powder within a gun is a sufficient cause for the motion of 

 the ball, but the explosion of the powder is not to the mind a 

 sufficient cause why the ball moves east rather than west, or in 

 any other direction. 



The grand and fundamental question then is, What is it that 

 determines or directs the action of the forces concerned in the 

 production of molecular change? The question therefore regards 

 not Law but Cause, unless we use the term law in an improper 

 sense. Law in physics is not an agent or force, it is simply the 

 process or mode of operation — not the force, but the path along 

 which the force acts. I know no clearer definition of law than 

 that given by Mr. Lewes, to which I have already referred. 



Suppose the subject of our inquiry to be the origin of a crys- 

 tal, the leaf of a tree, or any other special form, organic or 

 inorganic. We inquire, first, what is it that moves the particles 

 while the crystal or the leaf is being built up? We refer the motion 

 to 2i force, and feel satisfied with the explanation. But force or 

 energy accounts for the mere motion of the particles. We in- 

 quire, next, what are the particular paths taken by the moving 

 particles ? In what manner or way do they move to their posi- 

 tions ? In other words, what are the laws of their motions ? 

 But even if we knew this and could answer both of these ques- 

 tions, we should not be satisfied. We must not only know the 

 paths taken by the particles, but must be able also to explain why 

 the paths are taken. If we knew not simply the path, but the 



