146 THE WORLD-ENERGY 



mere "physical" force motion must forever remain inex- 

 plicable. According to that standpoint, all action is 

 and can be only from without. No single change in any 

 body in all the universe can take place save through 

 impressed forces; that is, forces acting upon the body 

 from without. And it only needs that this law be reso- 

 lutely followed round in all its applications to see that as 

 no portion of the -extended world contains within itself 

 as such any initial principle of motion, so it is absolutely 

 necessary to look beyond the merely physical phase of 

 the universe to find that principle. A system of merely 

 "impressed forces" could, as we have already seen, 

 only result in absolute equilibrium, excluding motion 

 absolutely. 



This, it need hardly be added, Newton saw with per- 

 fect clearness, and accordingly assumed a non-physical 

 cause of motion. 



And yet it is not to be overlooked that if the prin- 

 ciple of motion is not within, neither can it be beyond 

 the physical universe. For, were that principle wholly 

 beyond or outside the extended world, it could indeed 

 have no relation to that world. Or, if such relation be 

 allowed to be possible, it must at least leave the extended 

 world in a state of inertia, indifference, or passivity. 



So much, indeed, Newton's third law of motion really 

 implies. And yet, as was pointed out on a former page, 

 the " passive " is that which is acted upon, is that which 

 receives action. But, in this very fact of receiving action, 

 the " passive " necessarily also proves to be active. For 

 it can receive action only through itself reacting. Nay, 

 as we have already seen, action and reaction are but 

 complementary phases of every possible action in which 



