THE FAILURE OF SCIENTIFIC MATERIALISM. 597 



of the equivalent transformability of the different forms of 

 energy was too paradoxical in its simplicity to be immediately ac- 

 cepted. Rather have the three johysicists to whom we are most 

 indebted for the continued study of the law Helmholtz, Clausius, 

 and Lord Kelvin believed that it must be interpreted as imply- 

 ing that all the different forms of energy are fundamentally the 

 same mechanical energy. In this way, what was regarded as 

 most pressing close connection with the prevailing mechanical 

 conception of Nature was reached ; but a decisive side of the 

 new thought was lost. 



It required a half century for the idea to mature that this 

 hypothetical addition to the law of energy did not give depth to 

 the theory, but detracted from it on its most significant side 

 its freedom from all arbitrary hypothesis. And not even the 

 recognition of this methodical circumstance, but the ultimate 

 failure of all attempts satisfactorily to explain all the other forms 

 of energy mechanically, has been, so far as our advance has as yet 

 proceeded, the decisive reason for giving up the mechanical ex- 

 planation. 



You are impatient to learn how it is possible to form, by 

 means of so abstract an idea as energy, a theory of the world 

 that can compare in clearness and intuitiveness with the me- 

 chanical theory. I do not find the answer hard. What do we 

 know of the physical world ? Evidently only what our organs of 

 sense permit to reach us from it. But what are the conditions 

 under which these organs act ? Turn things as we will, we find 

 nothing common but that the sense organs react upon differences 

 of energy between them and the surroundings. In a world the 

 temperature of which is everywhere that of our body, we would 

 know nothing of heat, just as we have no idea of the constant 

 atmospheric pressure under which we live, and as we never gain 

 knowledge of it till we establish a different pressure. 



You will admit this, but you will not therefore give up mat- 

 ter, because energy must have a bearer. But I ask you, why ? 

 When all that we learn of the outer world are conditions of its 

 energy, what ground have we for presuming anything in this 

 same outer world of which we have never learned anything ? 

 Yes, I may be answered, energy is only something thought of, an 

 abstraction, while matter is real. I reply : The contrary ! Matter 

 is a thing of thought, which we have constructed for ourselves, 

 rather imperfectly, to represent what is permanent in the change 

 of phenomena. Now that we begin to comprehend that the effec- 

 tive thing that is, that which affects us is only energy, we have 

 to determine in what relations the two stand ; and the result is in- 

 dubitable that the predicate of reality can be ascribed only to 

 energy. 



