CHAPTEK XII. 



AKISTOTLE S ANHOMCEOMEBIA AND THEIK 

 FUNCTIONS (continued} . 



G. THE BRAIN AND SPINAL CORD. 



ARISTOTLE S views on the nature and functions of some 

 important organs of animals were very different from 

 modern views on the same subjects. This has been made 

 clear in the preceding chapters and is strikingly exempli 

 fied by his views on the brain and spinal cord. 



He believed that the brain was not a centre of sensation, 

 but a cooling means adapted to moderate the heat of the 

 body and to aid, or render more certain, the action of 

 the sensory organs, while the spinal marrow, being of a hot 

 nature, moderated the action of the brain. Such, speaking 

 generally, were his views. 



Some philosophers, he says, believe that sensation resides 

 in the brain, but this is not true, for, since the brain is quite 

 devoid of feeling, it cannot be a cause of sensation ; the 

 philosophers referred to are aware that the brain is the most 

 peculiar organ of the body, and that some of the sense 

 organs are lodged in the head. They cannot, he adds, find 

 out the cause of this, yet infer that the brain and sensation 

 are associated together, but it has been shown already that 

 the heart is the sensory centre.* 



Among philosophers who believed that the brain was 

 the centre of sensation were Diogenes of Apollonia and 

 Alcmseon. Aristotle clearly suggests that they reasoned on 

 insufficient data. He himself considered their views and 

 rejected them. His investigation and process of reasoning 

 about this subject exemplify both the excellences and defects 

 of his method. His observations on the brain, in one or 

 more animals, led him to believe that it was cold, that its 

 substance was bloodless, and that it was devoid of sensation ; 

 he also concluded that the brain was found in animals with 



* P. A. ii. c. 10, 656a. 



