CHAPTER VII. 



THE PERSISTENCE OF RELATIONS AMONG FORCES. 



§ 63. The first deduction to be drawn from the ultimate 

 universal truth that force persists, is that the relations 

 among forces persist. Supposing a given manifestation of 

 force, under a given form and given conditions, be either 

 preceded by or succeeded by some other manifestation, it 

 must, in all cases where the form and conditions are the 

 same, be preceded by or succeeded by such other manifesta- 

 tion. Every antecedent mode of the Unknowable must 

 have an invariable connexion, quantitative and qualitative, 

 with that mode of the Unknowable which we call its con- 

 sequent. 



For to say otherwise is to deny the persistence of force. 

 If in any two cases there is exact likeness not only between 

 those most conspicuous antecedents which we distinguish 

 as the causes, but also between those accompanying ante- 

 cedents which we call the conditions, we cannot affirm that 

 the effects will differ, without affirming either that some 

 force has come into existence or that some force has ceased 

 to exist. If the cooperative forces in the one case are 

 equal to those in the other, each to each, in distribution and 

 amount; then it is impossible to conceive the product of 

 their joint action in the one case as unlike that in the other, 

 without conceiving one or more of the forces to have in- 

 creased or diminished in quantity; and this is conceiving 

 that force is not persistent. 



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