IS THE BODY A MACHINE ? 61 



brain structure. Further, it is found that certain 

 visible changes occur in certain parts of the brain 

 the brain cells when they are excited into 

 mental activity. Such series of facts point to an 

 association between the mental side of sensations 

 and physical structure of the machine. But they 

 do not prove any correlation between them. 

 The unlikeness of mental and physical pheno- 

 mena is so absolute that we must hesitate about 

 drawing any connection between them. It is 

 impossible to conceive the mental side of a sensa- 

 tion as a form of wave motion. If, further, we 

 take into consideration the other phenomena 

 associated with the nervous system, the more 

 distinctly mental processes, we have absolutely 

 no data for any comparison. We cannot imagine 

 thought measured by units, and until we can 

 conceive of such measurement we can get no 

 meaning from any attempt to find a correlation 

 between mental and physical phenomena. It is 

 true that certain psychologists have tried to build 

 up a conception of the physical nature of mind ; 

 but their attempts have chiefly resulted in build- 

 ing up a conception of the physical nature of the 

 brain, and then ignoring the radical chasm that 

 exists between mind and matter. The possibility 

 of describing a complex brain as growing parallel 

 to the growth of a complex mind has been re- 

 garded as equivalent to proving their identity. 

 All attempts in this direction thus far have 

 simply ignored the fact that the stimulation of a 

 nerve, a purely physical process, is not the same 

 thing as a mental action. What the future may 

 disclose it is hazardous to say, but at present the 



