286 COSMIC rillLOSOPHY. [pt. 11. 



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 dependent upon 

 the manner in which objective experiences have registered 

 themselves upon our minds, our utter inability to conceive a 

 variation in the sum-total of force implies that such varia- 

 tion is negatived by the whole history of the intercourse 

 between the mind and its environment since intelligence 

 first began. The inconceivability-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 proposition whatever concerning any imagin- 

 able set of phenomena and under any conceivable circum- 

 stances, must be an axiom necessitated by the very constitu- 

 tion of the thinking mind, as perennial intercourse with the 

 environment has moulded it. 



Mr. Mill, indeed, in his " System of Logic," Book iii. Chap, 

 xxi., maintains that our belief in the necessity and universality 

 of causation (which was above shown 1 to be an immediate 

 corollary from the persistence of force) rests upon an induc- 

 tion per enumerationem simpliccm, which is, however, valid 

 in this one case, because it is coextensive with all known 

 orders of phenomena. The incompleteness of this view is 

 shown by the fact that the persistence of force is necessarily 

 assumed in every step of the vast induction by which the 

 1 See above, part i. chap. vi. 



