74 Darwinism and Oilier Essays. 



of heat, or that friction-electricity is a product of 

 sensible motion. Instead of entering into the dy 

 namic circuit of correlated physical motions, the 

 phenomena of consciousness stand outside as ut 

 terly alien and disparate phenomena. They stand 

 outside, but uniformly parallel to that segment 

 of the circuit which consists of neural undula 

 tions. The relation between what goes on in con 

 sciousness and what goes on simultaneously in the 

 nervous system may best be described as a re 

 lation of uniform concomitance. I agree with 

 Professor Huxley and Mr. Harrison that along 

 with every act of consciousness there goes a mo 

 lecular change in the substance of the brain, in 

 volving a waste of tissue. This is not materialism, 

 nor does it alter a whit the position in which we 

 were left by common sense before nervous physi 

 ology was ever heard of. Everybody knows that, 

 so long as we live on the earth, the activity of 

 mind as a whole is accompanied by the activity 

 of brain as a whole. What nervous physiology 

 teaches is simply that each particular mental act 

 is accompanied by a particular cerebral act. In 

 proving this, the two sets of phenomena, mental 

 and physical, are reduced each to its lowest terms, 

 but not a step is taken toward confounding the 

 one set with the other. On the contrary, the 



