362 THE RELATION OF MIND TO BODY 



602. Assuming, then, that brain and mind influence one another, 

 what is the connexion between the two ? It has been said very 

 crudely, but I think with some element of truth, that the brain 

 secretes thought as the liver secretes bile. It has been said equally 

 crudely that the mind, like heat and electricity, is a form of motion. 

 It has been said that mind and body are different aspects of the 

 same thing, a statement which is merely verbal in the sense that it 

 conveys no intelligible idea. It has been said that mind and body 

 are distinct but temporarily related things, and that mind bears the 

 same relation to body as the musician to his instrument ; in which 

 case the actions of the body are comparable to the music. It has 

 been thought that mind is the music that proceeds from the 

 instrument, the body, and that the environment is the musician, 

 the thing that stimulates the body, the brain, to produce the music. 

 This is the common-sense, and, I think, the correct, notion. But 

 it is a notion which is capable of expansion. 



603. To me, bearing in mind the theory of evolution, it seems 

 probable that thinking and feeling are forms of doing, and that the 

 brain is the doer; or, in other words, that mind is one of the 

 products of brain activity, one of the functions of the brain, one 

 of the things that it does. I say one of the things, for not only 

 does the brain, as I suppose, think and feel, but it receives and 

 despatches stimuli. I do not know how brain produces mind any 

 more than I know how one material body attracts another across 

 space. But, as far as I am able to judge, the evidence indicates 

 that mind arises only when there is an expenditure of energy in 

 the brain ; when there is no brain there is, apparently, no mind ; 

 when a portion of the brain is destroyed or injured, and ceases to 

 function, or functions imperfectly, a corresponding portion of the 

 mind is eliminated or is imperfect ; accordingly as the brains of the 

 higher animals are complex and ample so are their minds ; mental 

 exhaustion bears a relation to physical (brain) exhaustion ; and so 

 on. I assume, therefore, as the most probable conjecture, that 

 mind is somehow a consequence of the work of the brain. When 

 energy is expended in the muscles of the arm, molecular movements 

 occur, from which finally result the muscular contractions, by means 

 of which the arm is moved and the hand does its varied work. So, 

 apparently, when energy is expended under conditions which 

 exist in certain forms of nervous tissue (e.g. brains), mind results, 

 and the brain does its varied work. But when I think of the 

 chain of events that end in the movements of the hand, I think 

 from first to last of nothing but matter in motion. If I had a 



