MATTER 255 



destructible and impenetrable suffice to elucidate certain 

 physical and chemical properties of the bodies we con- 

 struct from atoms. But the continued existence of atoms 

 under physical changes and the reproduction of their 

 individuality on the dissolution of chemical combination 

 might possibly be deduced from other hypotheses than 

 those of the indestructibility and impenetrability of the 

 individual atom. It does not follow of logical necessity 

 that because we experience the same group of sense- 

 impressions at different times and in different places, or 

 even continuously, that there must be one and the same 

 thing at the basis of these sense-impressions. An example 

 will clearly show the reader what I mean and at the same 

 time demonstrate that however useful as hypotheses the 

 indestructibility and impenetrability of the atom may be, 

 they are still not absolutely necessary conceptions ; so 

 that even if we do project our atom into an imperceptible 

 of the phenomenal world, it will not follow that there 

 must be an unchangeable individual something at all 

 times and in all positions as the basal element of a per- 

 manent group of sense -impressions. The permanency 

 and sameness of the phenomenal body may lie in the 

 individual grouping of the sense-impressions and not in 

 the sameness of an imperceptible something projected 

 from conception into phenomena. 



The example we will take is that of a wave on the 

 surface of the sea. The wave forms for us a group of 

 sense-impressions, and we look upon it, and speak of it, as 

 if it were an individual thing. But we are compelled to 

 conceive the wave when it is fifty yards off as consisting 

 of quite different moving things from what it does when it 

 reaches our feet — the substratum of the wave has changed. 

 Throw a cork in ; it rises and falls as the wave passes it, 

 but is not carried along by it. The wave may retain its 

 form and be for us exactly the same group of sense- 

 impressions in different positions and at different times, 

 and yet its substratum may be continually changing. 

 We might even push the illustration further : we might 

 send two waves of different individual shapes (Fig. 19) 



