LAW OF CAUSATION. 255 



duced by the Conservation theory comes in : the property is itself an ef- 

 fect, and its cause, according to the theory, is a former motion of exactly 

 equivalent amount, which has been impressed on the particles of the body, 

 perhaps at some very distant period. But the case is simply one of those 

 we have already considered, in which the efficacy of a cause consists in its 

 investing an object with a property. The force said to be laid up, and 

 merely potential, is no more a really existing thing than any other proper- 

 ties of objects are really existing things. The expression is a mere arti- 

 fice of language, convenient for describing the phenomena : it is unneces- 

 sai'y to suppose that any thing has been in continuous existence except an 

 abstract potentiality. A force suspended in its operation, neither mani- 

 festing itself by motion nor by pressure, is not an existing fact, but a name 

 for our conviction that in appropriate circumstances a fact would take 

 place. We know that a pound weight, were it to fall from the earth into 

 the sun, would acquire in falling a momentum equal to millions of pounds ; 

 but we do not credit the pound weight with more of actually existing force 

 than is equal to the pressure it is now exerting on the earth, and that is 

 exactly a pound. We might as well say that a force of millions of pounds 

 exists in a pound, as that the force which will manifest itself when the 

 coal is burned is a real thing existing in the coal. What is fixed in the coal 

 is only a certain property : it has become fit to be the antecedent of an ef- 

 fect called combustion, which partly consists in giving out, under certain 

 conditions, a given definite quantity of heat. 



We thus see that no new general conception of Causation is introduced 

 by the Conservation theory. The indestructibility of Force no more in- 

 terferes with the theory of Causation than the indestructibility of Matter, 

 meaning by matter the element of resistance in the sensible world. It 

 only enables us to understand better than before the nature and laws of 

 some of the sequences. 



This better understanding, however, enables us, with Mr. Bain, to admit, 

 as one of the tests for distinguishing causation from mere concomitance, 

 the expenditure or transfer of energy. If the effect, or any part of the 

 effect, to be accounted for, consists in putting matter in motion, then any 

 of the objects present which has lost motion has contributed to the effect; 

 and this is the true meaning of the proposition that the cause is that one 

 of the antecedents which exerts active force. 



§ 11. It is proper in this place to advert to a rather ancient doctrine re- 

 specting causation, which has been revived during the last few years in 

 many quarters, and at present gives more signs of life than any other the- 

 ory of causation at variance with that set forth in the preceding pages. 



According to the theory in question. Mind, or to speak more precisely. 

 Will, is the only cause of phenomena. The type of Causation, as well as 

 the exclusive source from which we derive the idea, is our own voluntary 

 agency. Here, and here only (it is said), we have direct evidence of causa- 

 tion. We know that we can move our bodies. Respecting the phenom- 

 ena of inanimate nature, we have no other direct knowledge than that of 

 antecedence and sequence. But in the case of our voluntary actions, it is 

 affirmed that we are conscious of power before we have experience of re- 

 sults. An act of volition, whether followed by an effect or not, is ac- 

 companied by a consciousness of effort, "of force exerted, of power in ac- 

 tion, which is necessarily causal, or causative." This feeling of energy or. 

 force, inherent in an act of will, is knowledge a priori; assurance, prior to 



