THE VITAL IMPETUS 125 



nor anything physical. It is something concomitant 

 with the physico-chemical events involved in a nervous 

 process, an " epiphenomenon." We have to imagine 

 a " parallelism " between the mechanistic body and 

 the mind. But if we admit that consciousness may be 

 an effective agency in our behaviour, what is the differ- 

 ence between modern theories of physico-psychic 

 parallelism and the Cartesian theory of a rational soul 

 in association with an automatic body ? Descartes 

 denied the existence in animals other than man of the 

 rational soul ; the latter was not necessary. But he, 

 like us, must have been familiar with reflex actions and 

 must have seen that consciousness was not invariably 

 associated, even in himself, with bodily activity. And 

 he must have recognised the great distinction between 

 the intelligent acting of man and the instinctive 

 behaviour of the lower animals. There was something 

 in man that was not in the brute. 



Thus the first physiology, borrowing its ideas and 

 methods from the first physics, was, like the latter, a 

 mechanical science. After Galileo and Torricelli came 

 Borelli with his purely mechanical conceptions of 

 animal movement, and of the blood circulation, intro- 

 ducing even then mathematics into biology. There 

 was no chemistry in these speculations, though Basil 

 Valentine and Paracelsus and Van Helmont had 

 preceded Descartes and Borelli. This chemistry was 

 mystical, and though chemical reactions had been 

 studied in the organism, they were supposed to be 

 controlled by spiritual agencies, the " archei " of the 

 first bio-chemists. But that notion was to disappear, 

 and with Sylvius the conception of the animal body 

 as a chemical mechanism arose. All that was valuable 

 in Van Helmont 's chemistry was taken up by Sylvius, 

 but in his mind the fermentations of the older chemists 



