On the Scientific Study of Human Nature. 461 



an organ of mind, and demands an explanation, in terms of 

 its action. As the thought passes from consciousness, 

 something remains in the cerebral substratum, call it what 

 you will — trace, impression, residue. What the precise 

 character of these residua may be is perhaps questionable, 

 but it is impossible to deny their existence in some form 

 consistent with the nature of the cerebral structure and 

 activity. All thoughts, feelings, and impressions, when 

 disappearing from consciousness, leave behind them in the 

 nerve substance their effects or residua, and in this state 

 they constitute what may be termed latent or statical mind. 

 They are brought into consciousness by the laws of asso- 

 ciation, and there is much probability that in this uncon- 

 scious state they are still capable of acting and reacting, 

 and of working out true intellectual results. 



There are few who have not had experience of this un- 

 conscious working of the mind. It often happens that we 

 pursue a subject until arrested by difficulties which we can- 

 not conquer, when, after dismissing it entirely from the 

 thoughts for a considerable interval, and then taking it up 

 again, the obscurity and confusion are found to have cleared 

 away, the subject is opened in quite new relations, and 

 marked intellectual progress has been made. Nor can we 

 explain this by assuming that the arrest was simply due to 

 weariness, and the clearer insight to ther estoration of vigour 

 by rest, as after a refreshing night's sleep. Time enters 

 largely as an element of the case; weeks and months are 

 often required to produce the result, while the entirely 

 new development which the subject is found to have under- 

 gone, seems only explicable by the intermediate and uiicon- 

 scious activity of the cerebral centre. The brain also re- 

 ceives impressions and accumulates residua in partial or 

 total unconsciousness. In reading, for example, we gather 

 the sense of an author most perfectly while almost oblivi- 

 ous of the separate words. And thus, as Dr. Maudsley re- 



