MATTER, MOTION, AND FORCE 



an equation between something and nothing ; 

 and this cannot be done. That one is equal to 

 zero is a proposition of which the subject and 

 predicate will destroy each other sooner than be 

 made to unite. 



Thus the proof of our fundamental axiom is 

 not logical, but psychological. And, as was 

 formerly shown, this is the strongest possible 

 kind of proof. Inasmuch as our capacity for 

 conceiving any proposition is entirely depend- 

 ent upon the manner in which objective expe- 

 riences have registered themselves upon our 

 minds, our utter inability to conceive a variation 

 in the sum total of force implies that such vari- 

 ation is negatived by the whole history of the 

 intercourse between the mind and its environ- 

 ment since intelligence first began. The incon- 

 ceivability test of Kant and the experience test 

 of Hume, when fused in this deeper synthesis, 

 unite in declaring that the most irrefragable of 

 truths is that which survives all possible changes 

 in the conditions under which phenomena are 

 manifested to us. The persistence of force, 

 therefore, being an axiom which survives under 

 all conditions cognizable by our intelligence, 

 being indeed the ultimate test by which we are 

 compelled to estimate the validity of any pro- 

 position whatever concerning any imaginable 

 set of phenomena and under any conceivable 

 circumstances, must be an axiom necessitated by 

 H7 



