254 INDUCTION. 



hypothesis to suppose to have been stored up by the expenditure of an 

 equal amount of actual motion in some former state of the universe. Nor 

 does the motion produced by gravity take place, so far as we know, at the 

 expense of any other motion, either molar or molecular. 



It is proper to consider whether the adoption of this theory as a scien- 

 tific truth, involving as it does a change in the conception hitherto enter- 

 tained of the most general physical agencies, requires any modification in 

 the view I have taken of Causation as a law of nature. As it appears to 

 me, none whatever. The manifestations which the theory regards as 

 modes of motion, are as much distinct and separate phenomena when re- 

 ferred to a single force, as when attributed to several. Whether the phe- 

 nomenon is called a transformation of force or the generation of one, it has 

 its own set or sets of antecedents, with which it is connected by invariable 

 and unconditional sequence ; and that set, or those sets, of antecedents are 

 its cause. The relation of the Conservation theory to the principle of 

 Causation is discussed in much detail, and very instructively, by Professor 

 Bain, in the second volume of his Logic. The chief practical conclusion 

 drawn by him, bearing on Causation, is, that we must distinguish in the 

 assemblage of conditions which constitutes the Cause of a phenomenon, 

 two elements : one, the presence of a force ; the other, the collocation or 

 position of objects which is required in order that the force may undergo 

 the particular transmutation which constitutes the phenomenon. Now, it 

 might always have been said with acknowledged correctness, that a force 

 and a collocation were both of them necessary to produce any phenomenon. 

 The law of causation is, that change can only be produced by change. 

 Along with any number of stationaiy antecedents, which are collocations, 

 there must be at least one changing antecedent, which is a force. To pro- 

 duce a bonfire, there must not only be fuel, and air, and a spark, which are 

 collocations, but chemical action between the air and the materials, which 

 is a foi'ce. To grind corn, there must be a certain collocation of the parts 

 composing a mill, relatively to one another and to the corn ; but there must 

 also be the gravitation of water, or the motion of wind, to siipply a force. 

 But as the force in these cases was regarded as a property of the objects 

 in which it is embodied, it seemed tautology to say that there must be the 

 collocation and the force. As the collocation must be a collocation of ob- 

 jects possessing the force-giving property, the collocation, so understood, 

 included the force. 



How, then, shall we have to express these facts, if the theory be finally 

 substantiated that all Force is reducible to a previous Motion ? We shall 

 have to say, that one of the conditions of every phenomenon is an ante- 

 cedent Motion. But it will have to be explained that this needs not be 

 actual motion. The coal which supplies the force exerted in combustion 

 is not shown to have been exerting that force in the form of molecular 

 motion in the pit; it was not even exerting pressure. The stone on the 

 eminence is exerting a pressure, but only equivalent to its weight, not to 

 the additional momentum it would acquire by falling. The antecedent, 

 therefore, is not a force in action ; and we can still only call it a property 

 of the objects, by which they would exert a force on the occurrence of a 

 fresh collocation. The collocation, therefore, still includes the force. The 

 force said to be stored up, is simply a particular property which the object 

 has acquired. The cause we are in search of, is a collocation of objects 

 possessing that particular property. When, indeed, we inquire further into 

 the cause from which they derive that property, the new conception intro- 



