3o6 THE GRAMMAR OF SCIENCE 



telligible. On the other hand, to project the cause of 

 motion into something behind sense -impression is to 

 dogmatically assert causation where we cannot know, to 

 illogically infer from the like to the unlike (pp. 60, 156). 

 The only alternative is to consider force as an antecedent 

 group of sense-impressions ; this, however, is not only to 

 project our purely conceptual notions of motion into the 

 perceptual field, but it throws upon us the duty of defining 

 the particular group of sense-impressions to which force 

 corresponds. We have already spoken of the " muscular 

 sensation of force" (p. 273), which, if we project con- 

 ceptions into the perceptual field, is more accurately to be 

 described as a sense-impression of mutual acceleration 

 indissolubly linked to the fact of consciousness. It throws 

 absolutely no light on the cause of motion in such 

 " automata without consciousness," as we must conceive 

 " phenomenal corpuscles " to be. Hence, whichever way 

 we turn, the current definitions of both mass and force 

 lead us only into metaphysical obscurity. Mass as the 

 quantity of matter in a body, matter as that which 

 perceptually moves, force as that which changes its motion, 

 are solely and purely names which serve to cloak human 

 ignorance. This ignorance is at bottom the ignorance of 

 why there is routine in our sense-impressions, and with 

 this question of routine we have already fully dealt 

 (pp. 1 01-6). But science answers no why — it simply 

 provides a shorthand description of the Jiow of our sense- 

 impressions ; and it therefore follows that if mass and 

 force are to be used as scientific terms they must be 

 symbols by aid of which we describe this how. It is thus 

 that I have dealt with them ; we have seen that to briefly 

 describe the corpuscular dance, which forms our conceptual 

 model of the universe, the notions of mass and force as 

 based on mutual accelerations arise naturally and with 

 intelligible definitions. 



§ I O. — Equality of Masses tested by Weighing- 



Although it is impossible for us to review the whole 

 field of mechanics, it is still necessary to indicate to the 



