CHAPTER VIII 



THE LAWS OF MOTION 



S I. — Corpuscles and their Structure 



In the last chapter we have seen how the physicist 

 conceptually constructs the universe by aid of a vast 

 atomic dance. I use the word atom although it is most 

 probably the ultimate element of the ether, which we 

 ought to talk about as the fundamental unit of the dance. 

 Let us term this latter unit the ether-element, without 

 intending to assert b}^ the use of this word that the ether 

 is necessarily discontinuous.^ Two adjacent ether-elements 

 will be the symbols, necessarily geometrical, by which we 

 represent the relative motion of the parts of the ether. 

 On the basis of the ether-element let us try and conceive 

 how the physicist imagines his mechanical model of the 

 universe constructed. Perceptual experience gives us no 

 hint as to what we ought to conceive the ether-felement to 

 consist of, or how we ought to imagine it to act, if it 

 could be isolated. But we are compelled to consider 

 ether-elements when in each other's presence as moving in 

 certain definite modes, as taking part in a regulated dance. 

 Perceptually there is no reason for this dance, concep- 

 tually it enables us to describe the world of sense- 

 impressions. 



Probably, although this point is far from being definitely 

 settled, one type of motion among the ether-elements may 



1 If we suppose the ether to be a conceptual limit to a perceptual fluid or 

 jelly (pp. 262 and 274), then to conceptualise at all its transmission of 

 stress or its elasticity we are, I think, compelled to suppose it discontinuous. 



