CHAPTER IV 



THE CLASSIFICATION AND THE NOMENCLATURE OF 

 MENTAL OPERATIONS 



IF, as has been set forth in the preceding 

 chapter, all mental states are effects of physical 

 causes, it follows that what are called mental 

 faculties and operations are, properly speaking, 

 cerebral functions, allotted to definite, though not 

 yet precisely assignable, parts of the brain. 



These functions appear to be reducible to three 

 groups, namely : Sensation, Correlation, and Idea- 

 tion. 



The organs of the functions of sensation and 

 correlation are those portions of the cerebral 

 substance, the molecular changes of which give 

 rise to impressions of sensation and impressions of 

 relation. 



The changes in the nervous matter which bring 

 about the effects which we call its functions, follow 

 upon some kind of stimulus, and rapidly reaching 

 their maximum, as rapidly die away. The effect 

 of the irritation of a nerve-fibre on the cerebral 

 substance with which it is connected may be com- 



