r 



CHAPTEE XXX. 



CONSCIOUSNESS AND THOUGHT. 



"N the foregoing chapter, I have attempted an analysis of 

 the different mental functions, only so far as such an 

 analysis illustrates, and is illustrated by, the anatomy and 

 physiology of the organs of mind. That anatomy and 

 physiology are, I believe, most valuable guides for the first 

 few steps in the analysis of mental functions, but beyond 

 the first few steps they fail us altogether. I have no doubt 

 that Mind, in its very highest functions as truly as in mere 

 sensation, is dependent on nervous action ; but, beyond 

 broadly discriminating between the nerves of conscious- 

 ness, of thought, and of will, we have no means af iden- 

 tifying the nervous actions to which particular mental 

 Physio- actions are due. All psychology, therefore, except in its 

 usflessas ^°®* elementary parts, must be studied as a distinct 

 a guide in science, without further help from physiology. This, 

 element- howevex, is not because bodily and mental functions are 

 ary psy- really distinct, but only because we are unable to trace the 



chology, '' . , . . . 



though all connexion. But though it is impossible to trace the de- 



depemis on P^iidence of mental on nervous action in particular cases, 



nervous that dependence is proved as a general truth by all analogy, 



and by much direct evidence : such as the fact that great 



mental power is never found without a well-developed 



Proofs of cerebrum ^ (though the converse does not appear to be 



true) ; that mental exertion, like bodily exertion, exhausts 



I I do not say a large cerebrum. Great intellectual power is sometimes 

 met with in brains not above the average size. But there is certainly no 

 instance of great intellectual power in an abnormally small brain, or in a 

 malformed one. 



this. 



