210 ANIMAL AUTOMATISM. 



" Essay on Man," expressly, though still insufficiently, 

 acknowledges the resemblance of his fundamental con- 

 ceptions to those of Descartes ; and I shall now en- 

 deavour to show that a series of propositions, which 

 constitute the foundation and essence of the modern 

 physiology of the nervous system, are fully expressed 

 and illustrated in the works of Descartes. 



I. The ~brain is the organ of sensation, thought, and 

 emotion ; that is to say, some change in the con- 

 dition of the matter of this organ is the invari- 

 able antecedent of the state of consciousness to 

 which each of these terms is applied. 

 In the " Principes de la Philosophic " ( 169), Des- 

 cartes says: * 



" Although the soul is united to the whole body, its principal 

 functions are, nevertheless, performed in the brain ; it is here that 

 it not only understands and imagines, but also feels ; and this ia 

 effected by the intermediation of the nerves, which extend in the 

 form of delicate threads from the brain to all parts of the body, to 

 which they are attached in such a manner, that we can hardly touch 

 any part of the body without setting the extremity of some nerve 

 in motion. This motion passes along the nerve to that part of the 

 brain which is the common sensorium, as I have sufficiently ex- 

 plained in my Treatise on Dioptrics; and the movements which 

 thus travel along the nerves, as far as that part of the brain with 

 which the, soul is closely joined and united, cause it, by reason 

 of their diverse characters, to have different thoughts. And it is 

 these different thoughts of the soul, which arise immediately from 

 the movements that are excited by the nerves in the brain, which 

 we properly term our feelings, or the perceptions of our senses." 



* I quote, here and always, Cousin's edition of the works of Descartes, 

 as most convenient for reference. It is entitled " (Euvres completes de 

 Descartes," publiees par Victor Cousin. 1824. 



