Scope and Purport of Evolution 55 



vous systems. Into the endless circuit of transfor- 

 mations of molecular motion, says the materialist, 

 there enter certain phases which we call feelings 

 and thoughts ; they are part of the circuit ; they 

 arise out of motions of material molecules, and 

 disappear by being retransformed into such mo- 

 tions: hence, with the death of the organism in 

 which such motions have been temporarily gath- 

 ered into a kind of unity, all psychical activity and 

 all personality are ipso facto abolished. Such is 

 the materialistic doctrine, and such, I presume, is 

 what Professor Haeckel has in mind when he as- 

 serts that the belief in an immortal soul is incom- 

 patible with the doctrine of evolution. The theory 

 commonly called that of the correlation of forces, 

 and which might equally well or better be called the 

 theory of the metamorphosis of motions, is indis- 

 pensable to the doctrine of evolution. But for the 

 theory that light, heat, electricity, and nerve-action 

 are different modes of undulatory motion trans- 

 formable one into another, and that similar modes 

 of motion are liberated by the chemical processes 

 going on within the animal or vegetal organism, Mr. 

 Spencer's work could never have been done. That 

 theory of correlation and transformation is now 

 generally accepted, and is often appealed to by 

 materialists. A century ago Cabanis said that the 



