12 Mr. J. Croll on What determines Molecular Motion ? — 



be done in some special case or other. But I have never yet 

 seen the attempt made. Take the simplest of all special forms^ 

 viz. the crystal. In what possible way can we conceive the 

 crystalline form to be the product of forces ? If there be any 

 form in nature that can be accounted for by means of the ^' play 

 of forces/^ we should expect it to be the crystalline. But let 

 us see whether the theory generally held regarding the mode in 

 which the crystal is formed gives any support to the opinion 

 \^\\2X form can be the product of force. 



The particles or molecules of which the crystals are composed 

 are supposed to be of a certain definite shape ; and it is supposed 

 that they attract one another at certain definite points or along 

 certain definite lines. The molecules therefore cohere together in 

 a fixed and definite manner; and thus a figure in the form of a crys- 

 tal is the result. This may or it may not be the true explanation. 

 But it will be at once perceived that all that force does in the 

 matter in such a case is simply to move or draw the molecules 

 and hold them together in the crystalline state. The crystalline 

 form is therefore not due to the force, but to the original shape 

 of the constituent molecules, together with the fact that they 

 attract one another at definite points. Consequently that which 

 determined the form of the crystal is not the forces, but that 

 something, be it what it may, which is the cause why the mole- 

 cules have such a shape, and why their attraction is confined to 

 the definite points on the surfaces of the molecules. All that 

 the molecular forces do in the case under consideration is simply 

 to pull ; the form of the crystal is due not to the pull, but to 

 that something which gives to the constituent particles their 

 specific shape and directs the forces where and how to pull. 



In short,* let us in imagination form any conceivable hypo- 

 thesis as to how an organic or a crystalline figure may be pro- 

 duced by a force, and we shall always find, on subjecting our hy- 

 pothesis to a logical analysis, that the form and the arrangement of 

 the parts do not result from force, but from something else. We 

 need not in any way feel surprised at this ; for we are in reality, 

 as has been already shown, attempting to do what is in itself 

 absolutely impossible. The production of form or the arrange- 

 ment of parts by a force is what never is, was. or can be eff'ected. 



As the distinction between the production of motion and its 

 determination, or between the production of an act and its de- 

 termination, is absolute, it must hold equally true in the mental 

 world as in the physical. For example, it is just as impossible 

 to conceive the Will being determined by an act, as to conceive 

 the motion of the cannon-ball being determined by the explosion 

 of the powder. It is difficult to say whether in physics or in 

 metaphysics the distinction is of most importance. It would be 



