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sun, moon and stars, earth, sea and air, fountains and lakes, to have under- 

 standing and active power. * * * As philosophy advances, life 

 and activity in natural objects retires, and leaves them dead and inactive. 

 Instead of moving voluntarily, we find them to be moved necessarily ; instead 

 of acting, we find them to be acted upon ; and Nature appears to us one great 

 machine, where one wheel is turned by another, that by a third ; and how far 

 this necessary succession may reach the Philosopher does not know." 



But it will be asked, are not the various Forces which Modern Science 

 has detected, truly efficient causes ; which the Theist, if he please, may style 

 second causes, but which the scientific mind may rest upon as ultimate 1 ? 

 Ai'e not Gravitation, Elasticity, Cohesion, Attraction, Electricity, Magnetism, 

 Caloric, Chemical Affinity, and the rest, causes in this sense 1 ? To these 

 questions Hume and the Positivist school, with Mill and all his followers, 

 will still answer with an avowal of ignorance. For their philosophy knows 

 nothing but phenomena. Force, clearly, is no phenomenon, but the hidden 

 producer of phenomena. And in this answer the opposite sect in metaphysics 

 will most certainly concur. As Martineau shortly puts it, " Inductive Science 

 gives us no access to causes behind phenomena." Force is not matter, but 

 the supposed power which acts on matter. In itself it is invisible, inaudible, 

 impalpable, inaccessible, in short, to sense of any kind, or to any instruments 

 of sense. Its intensity, indeed, as appearing in its various effects of motion, 

 weight, elasticity, colour, heat, deflection of the needle, and so on, is, in most cases 

 measurable by appropriate methods. But the power itself lies outside the field 

 of observation ; like that veiled Egyptian goddess, whose hands, stretched forth 

 from her closely enwrapping mantle, alone were visible. " You sometimes 

 speak of gravity," Sir Isaac Newton writes to Bentley, "as essential and 

 inherent to matter. Pray do not ascribe that notion to me ; for the cause of 

 gravity is what I do not pretend to know." Here we have the great discoverer 

 avowing, that gravitation, according to his judgment, is not in itself a cause 

 but the effect of some ulterior and undiscovered agency. If this be the case 

 with gravity, it will scarcely be denied that the same is true of the entire 

 catalogue of forces I have above rehearsed, together with actinic force, kinetic, 

 and whatever other fresh coinage the always-active mind of scientific termin- 

 ology may hereafter issue for temporary circulation. All are but names, I will 

 not say to cover ignorance, although, in fact, they do conceal it, but to indicate 

 the supposed common origin of phenomena which appear connected. 



This will be made still plainer if we observe two contrary tendencies of 

 physical research. On the one hand, there is a tendency to augment the 

 number of supposed material forces arising from the continual discovery of 

 natural operations before unobserved. When such discovery occurs ; as in the 

 case of the action of light on certain salts of silver, (now become to lis so 

 familiar a fact in the arts of Photography ;) the new class of effects is ascribed, 

 for a time, to a new species of natural power. Thus Photography has taught 

 us to speak of the " actinic " power of light. But on the other hand investi- 

 gation is ever revealing to us the hidden analogies of Nature, and thus enabling 

 us to collect phenomena in larger groups, which we then refer to some one 

 form of force, instead of, as before, to several different forces. Here there is a 

 tendency to reduce the length of the Dynamic catalogue. This consideration 

 should satisfy us that the (so-called) physical agencies are plastic suppositions ; 

 hypotheses to serve a temporary purpose in scientific classification ; not exis- 

 tences of which we have any real knowledge. Moreover the tendency of 

 Modern Science is wholly to abandon the former notion of a multitude of 

 Forces, and to refer all natural operations to a single form of Force. Force 

 according to modem theory, never disappears in one shape without reappearing 

 in another, with exactly corresponding intensity. The blow of the smith's 



