LAWS OF MIND. 507 



otherwise, have either succeeded in establishing, or 

 shown ground for supposing it possible to establish 

 hereafter, I would not undertake to say. Nor do I 

 believe that the inquiry will be brought to a satisfac- 

 tory issue, while it is abandoned, as unfortunately it 

 has hitherto been, to physiologists who have no ade- 

 quate knowledge of mental laws, or psychologists who 

 have no sufficient acquaintance with physiology. 



It is certain that the natural differences which 

 really exist in the mental predispositions or suscepti- 

 bilities of different persons, are often not unconnected 

 with diversities in their organic constitution. But it 

 does not therefore follow that these organic differences 

 must in all cases influence the mental phenomena 

 directly and immediately. They may often affect them 

 through the medium of their psychological causes. 

 For example, the idea of some particular pleasure may 

 excite in different persons, even independently of 

 habit or education, very different strengths of desire, 

 and this may be the effect of their different degrees or 

 kinds of nervous susceptibility; but these organic 

 differences, we must remember, will render the plea- 

 surable sensation itself more intense in one of these 

 persons than in the other ; so that the idea of the 

 pleasure will also be an intenser feeling, and will, by 

 the operation of mere mental laws, excite an intenser 

 desire, without its being necessary to suppose that 

 the desire itself is directly influenced by the physical 

 peculiarity. As in this, so in many cases, such dif- 

 ferences in the kind or in the intensity of the physical 

 sensations as must necessarily result from differences 

 of bodily organization, will of themselves account for 

 many differences not only in the degree, but even in the 

 kind, of the other mental phenomena. So true is this, 

 that even different qualities of mind, different types of 



