XXIX.] THE PHYSIOLOGY OF MIND. 27 



sensation, which, after sensation itself, is the simplest and 

 most elementary of mental functions. Beyond and above 

 this are thought, and the consciousness of thought. I say 

 thought and the consciousness of thought, because, as the 

 consciousness of sensation is, as I believe, a distinct thing Conscious- 

 from the sensation itself, and there may be a sensation ^i^oi °^t jg 

 without the consciousness of it, so the consciousness of distinct 

 thought is a distinct thing from the thought itself, and thouo'lit. 

 there may be thought without the consciousness of it. 



Of the existence of unconscious thought there is ample Uncon- 

 evidence, and it is now generally admitted by those who tbousht 

 have studied psychology. To mention a single instance 

 of this — probably the commonest, but by no means the 

 most remarkable : it is only by admitting that trains of 

 thought, or suggestion, may go on in unconsciousness, that 

 we can account for the mental phenomenon, which must 

 often have come within every one's experience, of thoughts 

 and memories coming suddenly into consciousness without 

 anything whatever to suggest them, either in external cir- Eeoollec- 

 cumstances, or in the thoughts that were consciously '^^J^X 

 occupying the mind. I am myself very liable to this, apparent 

 Sometimes when my mind appears to be fully and con- ^^"'*^" 

 sciously occupied \ sometimes soon after wakening in the 

 night, and when consciousness is perfectly awake but not 

 occupied with any train of thought ; I find recollections 

 of places, of incidents, of lines of poetry, coming into 

 my consciousness. The things thus recalled are often 

 uninteresting and trivial, and they often, I feel certain, 

 have not been in my conscious memory for years. I 

 have frequently, on their occurrence, sought for any 

 possible link of conscious suggestion by wdiich to account 

 for them, and made myself certain that there was none. 



But there is no effect witliout a cause, and if these 

 recollections have not been suggested by any conscious 

 process they must have been suggested by an unconscious 

 one. It is scarcely possible to doubt that unconscious 

 thought, as well as consciousness, must be a function of 

 some part of the nervous system; every vital function, 

 sentient or insentient, appears to have its own peculiar 



