204 ANIMAL AUTOMATISM v 



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

 Descartes says : 1 



" 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 is effecte.l 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 explained 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." 



Elsewhere, 2 Descartes, in arguing that the seat 

 of the passions is not (as many suppose) the lu-art, 

 but the brain, uses the following remarkable 

 language : 



" The opinion of those who think that the soul receives its 

 passions in the heart, is of no weight, for it is based upon the 

 fact that the passions cause a change to be felt in that organ ; 

 and it is easy to see that this change is felt, as if it were in the 



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

 ])i-srartes, as iuo.>1 convenient for reference. It is entitled 

 - completes dc Descartes, publitcs, far Victor Cousin. 

 1824. 



8 Lcs Passions dc VAmc, Article xxxiii. 



