40 ON THE EDUCATIONAL VALUE n 



lie concluded at once that the act of falling was 

 not the result of any power inherent in the apple, 

 but that it was the result of the action of some- 

 thing else on the apple. In a similar manner, all 

 physical force is regarded as the disturbance of an 

 equilibrium to which things tended before its 

 exertion, to which they will tend again after its 

 cessation. 



The chemist equally regards chemical change 

 in a body as the effect of the action of something 

 external to the body changed. A chemical com- 

 pound once formed would persist for ever, if no 

 alteration took place in surrounding conditions. 



But to the student of Life the aspect of Nature 

 is reversed. Here, incessant, and, so far as we 

 know, spontaneous change is the rule, rest the 

 exception the anomaly to be accounted for. 

 Living things have no inertia, and tend to no 

 equilibrium. 



Permit me, however, to give more force and 

 clearness to these somewhat abstract considera- 

 tions by an illustration or two. 



Imagine a vessel full of water, at the ordinary 

 temperature, in an atmosphere saturated with 

 vapour. The quantity and the figure of that 

 water will not change, so far as we know, for 

 ever. 



Suppose a lump of gold be thrown into the vessel 

 motion and disturbance of figure exactly pro- 

 portional to the momentum of the gold will take 



