440 LOGIC OF THE MORAL SCIENCES. 



in virtue of which one thing is recognised by the mind, either 

 rightly or erroneously, as evidence of another thing. In 

 regard to Desire, they will have to examine what objects we 

 desire naturally, and by what causes we are made to desire 

 things originally indifferent, or even disagreeable to us ; and 

 so forth. It may be remarked, that the general laws of asso- 

 ciation prevail among these more intricate states of mind, in 

 the same manner as among the simpler ones. A desire, an 

 emotion, an idea of the higher order of abstraction, even our 

 judgments and volitions when they have become habitual, are 

 called up by association, according to precisely the same laws 

 as our simple ideas. 



4. In the course of these inquiries it will be natural 

 and necessary to examine, how far the production of one 

 state of mind by another is influenced by any assignable state 

 of body. The commonest observation shows that different 

 minds are susceptible in very different degrees, to the action 

 of the same psychological causes. The idea, for example, 

 of a given desirable object, will excite in different minds 

 very different degrees of intensity of desire. The same sub- 

 ject of meditation, presented to different minds, will excite 

 in them very unequal degrees of intellectual action. These 

 differences of mental susceptibility, in different individuals 

 may be, first, original and ultimate facts, or, secondly, they 

 may be consequences of the previous mental history of those 

 individuals, or thirdly and lastly, they may depend on varieties 

 of physical organization. That the previous mental history 

 of the individuals must have some share in producing or in 

 modifying the whole of their mental character, is an inevitable 

 consequence of the laws of mind ; but that differences of 

 bodily structure also co-operate, is the opinion of all physio- 

 logists, confirmed by common experience. It is to be re- 

 gretted that hitherto this experience, being accepted in the 

 gross, without due analysis, has been made the groundwork 

 of empirical generalizations most detrimental to the progress 

 of real knowledge. 



