CHAPTER VI. 



Differences in the Structure of same Internal Organs. 



The instrument of knowledge and reflection, the part by 

 whicli we feel, perceive, judge, think, reason — the organ or 

 organs connecting us with the external world, and executing 

 the moral and intellectual department in our economy — 

 claim our first attention. In spite of metaphysical subtlety, 

 of all the chimeras and fancies about immaterial agencies, 

 ethereal fluids, and the like, and all the real or pretended 

 alarms so carefully connected with this subject, the truth, 

 that the phenomena of mind are to be regarded physiologi- 

 cally merely as the functions of the organic apparatus con- 

 tained in the head, is proved by such overwhelming evidence 

 that physiologists and zoologists have been led, almost in 

 spite of themselves, to shew their belief in it, by the great 

 attention they have paid to this part. 



The vast superiority of man over all other animals in the 

 faculties of the mind, which may be truly considered as a 

 generic distinction of the human subject — in my opinion a 

 more unequivocal and important one than many of those, in 

 compliance with which, diversity of genus and species is 

 established in the animal kingdom — led physiologists at a 

 very early period to seek for some corresponding diff'erence 

 in the brains of man and animals. 



It has been asserted, from remote times, that the brain of 

 man is larger than that of any animal : and I know no ex- 

 ception to this assertion of Aristotle and Pliny, besides 

 the elephant ; unless the larger cetacea should be as well 

 supplied with brain, in proportion to tlieir size, as the 

 smaller. Certainly, all the larger animals, with which we 

 are more commonly acquainted, have brains absolutely 

 smaller, and considerably so, than that of man. This in- 

 deed may be easily shewn by a comparison of skulls ; by 



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