xiv.] ON DESCARTES &quot;DISCOURSE.&quot; 289 



laws ; while those of Harvey meant that the same laws presided 

 over the operations of that portion of the world which is nearest 

 to us, namely, our own bodily frame. And crossing the interval 

 between the centre and its vast circumference by one of the 

 great strides of genius, Descartes sought to resolve all the 

 phenomena of the universe into matter and motion, or forces 

 operating according to law. 1 This grand conception, which is 

 sketched in the &quot; Discours,&quot; and more fully developed in the 

 &quot;Principes&quot; and in the &quot;Traite de THornine,&quot; he worked out 

 with extraordinary power and knowledge; and with the effect 

 of arriving, in the last-named essay, at that purely mechanical 

 view of vital phenomena towards which modern physiology 

 is striving. 



Let us try to understand how Descartes got into this path, 

 and why it led him where it did. The mechanism of the 

 circulation of the blood had evidently taken a great hold of his 

 mind, as he describes it several times, at much length. After 

 giving a full account of it in the &quot; Discourse,&quot; and erroneously 

 describing the motion of the blood, not to the contraction of the 

 walls of the heart, but to the heat which he supposes to be 

 generated there, he adds : 



&quot;This motion, which I have just explained, is as much the necessary 

 result of the structure of the parts which one can see in the heart, and of 

 the heat which one may feel there with one s fingers, and of the nature of 

 the blood, which may be experimentally ascertained ; as is that of a clock 

 of the force, the situation, and the figure, of its weight and of its wheels.&quot; 



But if this apparently vital operation were explicable as a 

 simple mechanism, might not other vital operations be reducible 

 to the same category ? Descartes replies without hesitation in 

 the affirmative. 



&quot;The animal spirits,&quot; says he, &quot;resemble a very subtle fluid, or a very 

 pure and vivid flame, and are continually generated in the heart, and ascend 



1 &quot; Au milieu de toutes ses erreurs, il ne faut pas meconnaitre une grande 

 idee, qui consiste a avoir tent6 pour la premiere fois de ramener tous les 

 phenomenes naturels a n etre qu un simple develloppement des lois de la 

 m^canique,&quot; is the weighty judgment of Biot, cited by Bouillier (Histoire 

 de la Philosophic Cartesienne, tA p. 196). 



U 



