130 



HUXLEY 



No one who is cognisant of the facts of the case 

 nowadays doubts that the roots of psychology lie in the 

 physiology of the nervous system. What we call the 

 operations of the mind are functions of the brain, 

 and the materials of consciousness are products of 

 cerebral activity. Cabanis may have made use of 

 crude and misleading phraseology when he said that 

 the brain secretes thought as the liver secretes bile ; 

 but the conception which that much-abused phrase 

 embodies is, nevertheless, far more consistent with 

 fact than the popular notion that the mind is a 

 metaphysical entity seated in the head, but as inde- 

 pendent of the brain as a telegraph operator is of his 

 instrument. 



It is hardly necessary to point out that the doctrine 

 just laid down is what is commonly called materialism. 

 But it is, nevertheless, true that the doctrine contains 

 nothing inconsistent with the purest idealism. For 

 as Hume remarks (as indeed Descartes had observed 

 long before) : — " 'Tis not our body we perceive when 

 we regard our limbs and members, but certain im- 

 pressions which enter by the senses ; so that the as- 

 cribing a real and corporeal existence to these im- 

 pressions, or to their objects, is an act of the mind as 

 difficult to explain as that (the external existence of 

 objects) which we examine at present." Therefore, 

 if we analyse the proposition that all mental phenom- 

 ena are the effects or products of material phenom- 

 ena, all that it means amounts to this; that whenever 

 those states of consciousness which we call sensation, 

 or emotion, or thought come into existence, complete 

 investigation will show good reason for the belief that 

 they are preceded by those other phenomena of con- 

 sciousness to which we give the names of matter and 

 motion. All material changes appear, in the long- 

 run, to be modes of motion ; but our knowledge of 

 motion is nothing but that of a change in the place 



