CHAPTER X. 



1 



INTELLECTUAL AND MORAL FACULTIES. 



J. THE great superiority of the intellectual faculties of 

 man over those of other animals, has led to a diligent exami- 

 nation, whether there be any thing in his anatomical struc- 

 ture which would seem to account for this superiority. 

 Aristotle noticed the great size of the human brain compared 

 with that of other animals, andjlaid it down as a general 

 principle, that the faculties referred to this organ were in 

 proportion to its size, compared with that of the whole bodyV 

 Though this rule will hold true in relation to some of the do- 

 mestic animals, yet it does not in relation to many others, 

 for accurate researches have shown that whil^in man the 

 ratio of the weight of the brain to that of the whole body is 

 as 1 to 28j?in the dog, it is as 1 to IGO^in the horse, as 1 to 

 400") (n the elephant, 1 to 500){n the "canary bird, 1 to IV 

 (and in one species of ape, 1 to 11.) 



2. It is now generally admitted by physiologists,, that the 

 perfection of the sensitive functions does not depend on the 

 absolute size of the brain, nor on its proportion to the body 

 at large, but(upon the proportion between the size of the 

 brain, and the aggregate bulk of the nerves that proceed 

 from it ; in other words,fbetween the sensorial and nervous 

 organs^ For example, the absolute size of the brain of the 

 horse is only about half the size of the human brain, while 

 the mass of the nerves of the horse at their origin is no less 

 than ten times larger than that of man. Extensive observa- 

 tions prove that though most of the inferior animals have larger 

 nerves, and possess some of the nervous functions in a much 

 more acute state than mnn. yet man decidedly exceeds them 

 all in the comparative size of the brain, and in the perfection 

 of his intellectual faculties. 





