260 The Older Doctrines [lect. 



" And so the learned anatomist trained in the dissection of dead 

 " bodies, and tainted with no heresy, will readily understand 

 " how little I should be consulting my own interests were I to 

 " lecture on the results to be obtained by the vivisection of the 

 " brain, which otherwise I would most willingly have done, and 

 "indeed at great length." 



In this as in almost everything else which Vesalius wrote 

 there is a wholly modern ring. We seem to be stepping 

 backwards again when nearly a hundred years later we come 

 to the views of van Helmonf) and Descartes. I put these 

 together, for the sensitive and motive soul of van Helmont 

 and the rational soul of Descartes, though the latter includes 

 van Helmont's immortal mind, are alike in this that they are 

 both outside and distinct from the animal spirits, the activities 

 of the nervous tissues themselves. That the seat of the soul 

 is placed by one in the pylorus and by the other in the pineal 

 gland is a matter of indifference. The essential point of both 

 views is that the soul is something added to, different from the 

 mere results of the action of the tissues of the brain. This 

 permitted Descartes to accept and make use of the strictest 

 physical conceptions of the nervous phenomena themselves. 



To Descartes the whole body was nothing but a machine 

 whose motive power lay in that heat which was innate in the 

 heart though fed and sustained by the food carried to it in 

 the blood ; in this respect he, rejecting the modern doctrines of 

 Harvey and others, followed the teaching of the ancients. To 

 him the whole body was nothing but a machine, in which the 

 blood, heated and rarefied in the heart, engendered " the very 

 " subtle air or rather the very lively and pure flame, called the 

 "animal spirits," which in turn in that part of the machine 

 called the brain and nervous system on the one hand carried 

 out according to simple physical and mechanical laws all the 

 movements of the body in response to changes in the environ- 

 ment, and on the other hand, by supplying the physical basis 

 for and by working on the rational soul, gave rise to modifica- 

 tions of thought. 



Though he speaks of the animal spirits as an 'air' or a 

 ' wind ' or a ' flame,' yet throughout he treats them as if they 



