84 ' LIFE AND DEATH. 



and which was formed at the expense of the carbonic 

 acid of the air. The plant had separated, at the 

 expense of the solar energy, the carbon from the 

 oxygen to which it was united in the carbonic acid of 

 the atmosphere. It had created the system C + 2O. 

 So that the solar energy produces the chemical poten- 

 tial energy which was so long before it was utilized. 

 Combustion expends this energy in making carbonic 

 acid over again. 



Materialization of Energy. — The fertility of the 

 idea of energy is therefore, as we see from all 

 these examples, due to the relations it establishes 

 between the natural phenomena of which it exhibits 

 the necessary relation, destroyed by the excessive 

 analysis of early science. It shows us that in the 

 world of phenomena there is nothing but trans- 

 formations of energy. And we regard these trans- 

 formations themselves as the circulation of a kind of 

 indestructible agent which passes from one form of 

 determination to another, as if it were simply putting 

 on a fresh disguise. If our intellect requires images 

 or symbols to embrace the facts and to grasp their 

 relation, it may introduce them here. It will materialize 

 energy, it will make of it a kind of imaginary being, 

 and confer upon it an objective reality. And for the 

 mind, as long as it does not become the dupe of the 

 phantom which it itself has created, this is an 

 eminently comprehensive artifice which enables us 

 to grasp readily the relations between phenomena 

 and their bond of affiliation. 



The world appears to us then, as we said at the 

 outset, constructed with singular symmetry. It offers 

 to us nothing but transformations of matter and 

 transformations of energy ; these two kinds of meta- 



