164 UNIVERSAL EVOLUTION 



from a square. There is a frontier where virtue and 

 vice fade into each other. Who has ever been able to 

 define the exact boundary between courage and rash- 

 ness, between prudence and cowardice, between fru- 

 gality and avarice, between liberality and prodigality ? ' ' 

 This is so because the extreme mobility of our nervous 

 action, and the intimate meshes of its conduction paths, 

 the perpetual motion of its minute particles, make the 

 psychical phenomena so blend that the subject fails to 

 perceive the true line of demarcation. They cannot be 

 measured mathematically. So it is with our conception 

 of the unconscious process of thinking. It eludes the 

 subtlest mathematical tests because the measurements 

 cannot be applied to the material substance of the brain 

 while it is in action, as it can to muscular tissue in a 

 mere reflex action. If the brain is simply a bundle of 

 nerves, however, to convey spirit, as copper wire carries 

 electricity, then science should turn its attention to the 

 study of "spirit," as it does to radio activity. But 

 when it undertakes to do that, it finds nothing but a 

 blank, nothing is found except molecular motion, 

 accompanied with explosions of energy, and that is 

 measurable as such, in metabolism. 



The division of the human organism into a duality, 

 physical and psychical, and the treatment of the 

 psychical, in the last few pages, as the product of evolu- 

 tion, is necessary only in view of the commonly 

 accepted theory that the psychical is a distinct entity. 

 But it is entirely unnecessary to the monist, who holds 

 that the organism is a psycho-physical unit, the psychic 

 being a function of the physical. The monist holds that 

 the proof of the evolution of the body carries with it the 

 proof of the evolution of all the manifestations of its 

 structure. 



