THE CEREBRUM, AND ITS FUNCTIONS. 791 



however, in which processes of a far more elaborate nature are carried on, with- 

 out necessarily affecting our consciousness. Most persons who attend to their 

 own mental operations are aware that when they have been occupied for some 

 time about a particular subject, and have then transferred their attention to 

 some other, the first when they return to the consideration of it, may be found 

 to present an aspect very different from that which it possessed before it was 

 put aside ; notwithstanding that the mind has since been so completely en- 

 grossed with the second subject, as not to have been consciously directed 

 towards the first in the interval. Now a part of this change may depend upon 

 the altered condition of the mind itself, such as we experience when we take up 

 a subject in the morning with all the vigor which we derive from the refresh- 

 ment of sleep, and find no difiiculty in overcoming difficulties and in disentan- 

 gling perplexities which checked our further progress the night before, when 

 we were too weary to give more than a languid attention to the points to be 

 made out, and could use no exertion in the search for their solutions. But this 

 by no means accounts for the entirely new development which the subject is 

 frequently found to have undergone, when we return to it after a considerable 

 interval; a development which cannot be reasonably explained in any other 

 mode, than by attributing it to the intermediate activity of the Cerebrum, which 

 has in this instance automatically evolved the result without our consciousness. 

 Strange as this phenomenon may at first sight appear, it is found, when carefully 

 considered, to be in complete harmony with all that has been affirmed in the pre- 

 ceding paragraphs, respecting the relation of the Cerebrum to the Sensorium, 

 and the independent action of the former j and looking at all those automatic 

 operations by which results are evolved without any intentional direction of the 

 Mind to them, in the light of " reflex actions" of the Cerebrum, there is no 

 more difficulty in comprehending that such reflex actions may proceed without 

 our knowledge, so as to evolve intellectual products when their results are 

 transmitted to the Sensorium and are thus impressed on our consciousness, than 

 there is in understanding that impressions may excite muscular movements, 

 through the "reflex" power of the Spinal Cord, without the necessary inter- 

 vention of Sensation. In both cases, the condition of this form of independent 

 activity is that the receptivity of the Sensorium shall be suspended quoad the 

 changes in question, either by the severance of structural connection, or through 

 its temporary engrossment by other objects. 1 



819. It is difficult to find an appropriate term for this class of operations. 

 They can scarcely be designated as Reasoning Processes, since " unconscious 

 reasoning" is a contradiction in terms. The designation Unconscious Cerebration 

 is perhaps less objectionable than any other. But it must not be left out of view, 

 that emotional states, or rather states which constitute emotions when we become 

 conscious of them, may be developed by the same process ; so that our feelings 



1 It may serve to give the readers of this Treatise more confidence than they might other- 

 wise feel in the truth of the above doctrine, if the author mentions that, having been led 

 to entertain it as possible on purely Physiological grounds, he then began to question not 

 merely his own experience, but that of others, as to the Psychological evidence of uncon- 

 scious Cerebral activity. Having found enough in the results of this inquiry to convert 

 the possibility into a probability, he next took an opportunity of placing his views before 

 two of the deepest thinkers of the present day, Sir W. Hamilton and Mr. John Stuart Mill. 

 From the former he learned that the doctrine had been advanced by Leibnitz more than 

 two centuries since ; and that the first of the above illustrations had actually been adduced 

 by that eminent philosopher in its support. By the latter he was assured that the fact of 

 the unconscious development of a subject of thought was so familiar to him, that, when 

 he found it difficult to pursue an inquiry further, not seeing his way clearly through its 

 entanglements, he was accustomed to lay it aside for weeks or even months, and to devote 

 himself to some other object, with the full expectation (derived from frequent experience) 

 of being able to prosecute his first investigation with diminished difficulty, whenever he 

 might feel disposed to resume it. 



