268 The Older Doctrines [lect. 



" hand when the body has all its organs properly arranged for 

 "a particular movement, it has no need of the soul to carry 

 " this out. Hence all movements except those which we know 

 " to depend upon thought ought not to be attributed to the 

 " soul but to the mere disposition of organs, and even the move- 

 "ments which we call voluntary depend principally on the 

 "same disposition of the organs (though it is the soul which 

 " is the determining cause) since without such a proper 

 "disposition we cannot carry them out, however much we 

 " will to do so. Because the movements cease when the body 

 " dies and the soul quits it, we must not therefore infer that it 

 " is the soul which produces them, since it is one and the same 

 " cause which on the one hand renders the body unfit to produce 

 " the movements and on the other hand leads the soul to quit 

 " the body." 



If we judge Descartes from the severe standpoint of exact 

 anatomical knowledge, we are bound to confess that he, to a 

 large extent, introduced a fantastic and unreal anatomy in 

 order to give clearness and point to his exposition. From this 

 standpoint we cannot consider him as contributing to the 

 progress of physiology ; he stands in this respect wholly aside 

 from Harvey or from other men of whom we are about to speak. 

 On the other hand, however, we must admit that he did succeed 

 in shewing that it was possible to apply to the interpretation 

 not only of the physical but also of the psychical phenomena of 

 the animal body, the same method which was making such 

 astounding progress when applied to the phenomena of the 

 material world. And indeed a very little change in the details 

 of Descartes' exposition and some of that hardly more than a 

 change in terminology w T ould convert that exposition into a 

 statement of modern views. If we read between the lines 

 which he wrote, if we substitute in place of the subtle fluid 

 of the animal spirits, the molecular changes which we call a 

 nervous impulse, if we replace his system of tubes with their 

 valvular arrangements by the present system of concatenated 

 neurons, whose linked arrangement determines the passage and 

 the effects of the nervous impulses, Descartes' exposition will 

 not appear so wholly different from the one which we give to-day. 



