THE DOCTRINE OF ENERGY 87 



the continued existence in posse, if not in esse, 

 of the Energy which by appropriate action he can 

 again reveal in an active or kinetic manifestation. 

 Hence arises the conception of potential Energy. 

 The Energy to which we attribute the force of 

 cohesion which any particular body can on occasion 

 manifest, we believe to exist potentially whilst 

 that body continues unacted upon. Our belief is 

 confirmed by our experience of the certainty with 

 which, on the recurrence of the given conditions, 

 the force always again manifests itself. In like 

 manner the potential Energy to which we attribute 

 the Force of Gravitation we believe to exist at all 

 times, even when not kinetically active. Indeed, it 

 only manifests itself when a transmutation is 

 taking place into some other form of Energy. 

 Now it is the universal association of these two 

 forms of potential Energy with the common and 

 fundamental data of our sense-experience that has 

 suggested the construction in our minds of the 

 conception of Matter, and furnished us with the 

 ideas of solidity, impenetrability, and weight which 

 constitute its groundwork. 



Our view, therefore, is that the concept of materi- 

 ality can, in the way just indicated, be in all cases 

 analysed into, and derived from, the conception of 

 Energy ; and that Science, if consistent, cannot 



