FUNCTIONS OF THE BRAIN. J>7 



but cannot possibly reflect, imagine, judge ? Who has ap- 

 preciated them so exactly, as to be able to decide that it 

 can execute the mental functions of an elephant, a dog, or 

 an orang-utang, but cannot perform those of a Negro or 

 a Hottentot ? 



To say that a thing of merely negative properties, that is, 

 an immaterial substance, which is neither evidenced by any 

 direct testimony, nor by any, indirect proof from its effects, 

 does exist, and can think, is quite consistent in those who 

 deny thought to animal structures, where we see it going 

 on every day. 



If the mental processes be not the function of the brain, 

 what is its office ? In animals which possess only a small 

 part of the human cerebral structure sensation exists, and 

 in many cases is more acute than in man. What employ- 

 ment shall we find for all that man possesses over and 

 above this portion — for the large and prodigiously deve- 

 loped human hemispheres ? Are we to believe that these 

 serve only to round the figure of the organ, or to fill the 

 cranium ? 



It is necessary for you to form clear opinions on this sub- 

 ject, as it has immediate reference to an important branch 

 of pathology. They who consider the mental operations 

 as acts of an immaterial being, and thus disconnect the 

 sound state of the mind from organization, act very con- 

 sistently in disjoining insanity also from the corporeal struc- 

 ture, and in representing it as a disease, not of the brain, 

 but of the mind. Thus we come to disease of an immate- 

 rial being, for which, suitably enough, moral treatment 

 has been recommended. 



I firmly believe, on the contrary, that the various forms 

 of insanity, that all the affections comprehended under the 

 general term of mental derangement, are only evidences of 

 cerebral affections, disordered manifestations of those organs 

 whose healthy action produces the phenomena called men- 

 tal ; in short, symptoms of diseased brain. 



These symptoms have the same relation to the brain, as 



H 



