3i6 THE GRAMMAR OF SCIENCE 



symbolise physical bodies. It is a conceptual link be- 

 tween those geometrical forms and the accelerations with 

 which we endow them. The importance of this point 

 must be insisted upon, for it is this relation between 

 geometrical volume and mass in the case of homogeneous 

 substances which led physicists to the definition of mass 

 as the "quantity of matter in a body" (p. 303). The 

 geometrical form was first projected into the phenomenal 

 world, and then this form filled with the metaphysical 

 source of sense- impressions — matter. Mass as pro- 

 portional to volume thus became mass as a measure of 

 matter, and the sluice-gate was opened for that flood of 

 metaphysics which has threatened to undermine the solid 

 basis of physical science. 



§ 13. — The Influence of Aspect ojt the Corpuscular Dance 



Hitherto I have only been dealing with the value of 

 the ratio of the mutual accelerations of two corpuscles. 

 The discussion of the absolute values of these mutual 

 accelerations for each individual field would carry us 

 through the whole range of modern physics ; we should 

 have to deal with those special laws of motion which 

 describe the phenomena we class under the heads of 

 cohesion, gravitation, capillarity, electrification, magnetisa- 

 tion, etc. To discuss these does not fall within the 

 scope of my present work, but there are one or two 

 general points I must notice here. I proceed, in the 

 first place, to state in accurate terms the second problem 

 suggested on p. 299. I ask : Are the absolitte magnitudes 

 of the mutual accelerations of two corpuscles influenced by 

 the aspect they present to each other ? 



Now no very decisive answer can yet be given to this 

 very im.portant question of aspect influence. If we dis- 

 criminate between the various types of corpuscles, there 

 seem no facts of our perceptual experience that would 

 lead us to suppose that aspect plays any part in the 

 mutual action of ether-elements. With regard to the 

 prime-atom, we can only leave the matter unsettled ; if 



