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FUNCTIONS OF THE BRAIN. 563 



The question, however, still recurs; — What 

 relation does all this artificial intertexture and 

 accumulation of fibres bear to the mental ope- 

 rations of which we are conscious, such as 

 memory, abstraction, judgment, imagination, 

 volition? Are there localities set apart for our 

 different ideas in the store-house of the cerebral 

 hemispheres, and are they associated by the 

 material channels of communicating fibres ? 

 Are the mental phenomena the effects, as was 

 formerly supposed, of a subtle fluid, or animal 

 spirits, circulating with great velocity along 

 invisible canals in the nervous substance? or 

 shall we, with Hartley, suppose them to be the 

 results of vibrations and vibratiuncles, agitating 

 in succession the finer threads of which this 

 mystic web has been constructed ? But a little 

 reflection will suffice to convince us that these, 

 and all other mechanical hypotheses, which the 

 most fanciful imagination can devise, make not 

 the smallest approach to a solution of the diffi- 

 culty ; for they, in fact, do not touch the real 

 subject to be explained, namely, how the affec- 

 tions of a material substance can influence and 

 be influenced by an immaterial agent. All that 



generally supposed. He observed that its fibres are interlaced 

 in the most intricate manner, resembling the plexuses met with 

 among the nerves, and establishing the most extensive and 

 general communications between every part of the cerebral 

 mass. 



