VITALITY. 417 



&quot; The external objects which, by their mere presence, act upon the 

 organs of the senses ; and which, by this means, determine the corporal 

 machine to move in many different ways, according as the parts of the 

 brain are arranged, are like the strangers who, entering into some of the 

 grottoes of those water-works, unconsciously cause the movements which 

 take place in their presence. For they cannot enter without treading upon 

 certain planks so arranged that, for example, if they approach a bathing 

 Diana, they cause her to hide among the reeds ; and if they attempt to 

 follow her, they see approaching a Neptune, who threatens them with his 

 trident ; or if they try some other way, they cause some monster who 

 vomits water into their faces, to dart out ; or like contrivances, according 

 to the fancy of the engineers who have made them. And lastly, when 

 the rational soul is lodged in this machine, it will have its principal seat 

 in the brain, and will take the place of the engineer, who ought to be 

 in that part of the works with which all the pipes are connected, when 

 he wishes to increase, or to slacken, or in some way to alter, their move 

 ments.&quot; 



&quot; All the functions which I have attributed to this machine &quot; (the 

 body), &quot; as the digestion of food, the pulsation of the heart and of the 

 arteries ; the nutrition and the growth of the limbs ; respiration, wake- 

 fulness, and sleep ; the reception of light, sounds, odors, flavors, 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 imagina 

 tion ; 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 im 

 pressions which meet in the memory, that they imitate as nearly as 

 possible those of a real man : 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; 



