Relations between the Physical and the Moral. 253 



to another substance it does not know matter without being able 

 to reconcile them, as is natural, for how can light be produced out 

 of the clash of two ignorances ? On the contrary, the partisan 

 of experience pronounces the question unsolvable, precisely because 

 it transcends experience, that is to say, demonstrated or verifiable 

 science. The one is pent within the impotency of his metaphysics ; 

 the other within the limits of his method. The ignorance of the 

 former is owing to the gaps in his philosophy ; that of the latter, 

 to his voluntary abstention from all transcendental research. 



In our times, the fine generalization known as the law of equiva- 

 lence, or of the correlation of forces, has led some bold thinkers to 

 state in another form the problem of the relations between the 

 physical and the moral. Modern physics considers all the forces 

 of nature heat, light, electricity, magnetism, cohesion, chemical 

 affinity, gravity as capable of being reduced all to one principle, 

 and of being transformed into one another in accordance with 

 fixed rules, which are nothing else but the laws of mechanics. It- 

 is also generally admitted that the law of equivalence governs 

 vital phenomena, and muscular contraction and innervation in par- 

 ticular. But is it also applicable to mental phenomena ? Is it 

 possible for it to pass from nerve facts to states of consciousness ? 

 Do mental forces enter the category of the other forces, and are 

 they in like manner convertible ? 



Some authors in our day answer affirmatively. Bain has accu- 

 mulated and cited some facts from which he infers, (i) the equiva- 

 valence or transmutability of nervous and mental forces, and (2) 

 the equivalence or transformation of the mental forces into one 

 another. Thus, according to him, it would be possible to establish 

 an equivalence on the one hand between a certain nervous state 

 and a certain mental state, and on the other hand between the 

 three principal forms of mental life sensibility, will and intelli- 

 gence ; so that a state of consciousness would imply the trans- 

 formation and expenditure of a certain amount of nerve-force ; 

 and an increase of sensibility would be possible only by a diminu- 

 tion of intelligence and will, the sum of force in the living being 

 remaining constant amid all these transformations. The magnifi- 

 cent synthesis contained in Herbert Spencer's First Principles 

 reduces all phenomena without exception to the law of equivalence. 



