xiv.] ON DESCARTES &quot; DISCOURSE.&quot; 291 



nutrition and the growth of the limbs ; respiration, wakefulness, and sleep ; 

 the reception of light, sounds, odours, flavours, heat, and such like qualities, 

 in the organs of the external senses ; the impression of the ideas of these 

 in the organ of common sense and in the imagination ; the retention, or 

 the impression, of these ideas on the memory ; the internal movements of 

 the appetites and the passions ; and lastly, the external movements of all 

 the limbs, which follow so aptly, as well the action of the objects which 

 are presented to the senses, as the impressions which meet in the memory, 

 that they imitate as nearly as possible those of a real man : l I desire, I say, 

 that you should consider that these functions in the machine naturally 

 proceed from the mere arrangement of its organs, neither more nor less 

 than do the movements of a clock, or other automaton, from that of its 

 weights and its wheels ; so that, so far as these are concerned, it is not 

 necessary to conceive any other vegetative or sensitive soul, nor any other 

 principle of motion, or of life, than the blood and the spirits agitated by 

 the fire which burns continually in the heart, and which is no wise essentially 

 different from all the fires which exist in inanimate bodies.&quot; 2 



The spirit of these passages is exactly that of the most 

 advanced physiology of the present day ; all that is necessary 

 to make them coincide with our present physiology in form, 

 is to represent the details of the working of the animal 

 machinery in modern language, and by the aid of modern 

 conceptions. 



Most undoubtedly, the digestion of food in the human body is 

 a purely chemical process ; and the passage of the nutritive parts 

 of that food into the blood, a physical operation. Beyond all 

 question, the circulation of the blood is simply a matter of 

 mechanism, and results from the structure and arrangement of 

 the parts of the heart and vessels, from the contractility of those 

 organs, and from the regulation of that contractility by an 

 automatically acting nervous apparatus. The progress of 

 physiology has further shown, that the contractility of the 

 muscles and the irritability of the nerves are purely the results 

 of the molecular mechanism of those organs ; and that the 

 regular movements of the respiratory, alimentary, and other 

 internal organs are governed and guided, as mechanically, by 



1 Descartes pretends that he does not apply his views to the human 

 body, but only to an imaginary machine which, if it could be constructed, 

 would do all that the human body does ; throwing a sop to Cerberus 

 unworthily ; and uselessly, because Cerberus was by no means stupid 

 enough to swallow it. 



2 &quot;Traits de 1 Homme,&quot; p. 427. 



u 2 



