160 Sylvius and his Pupils. [lect. 



might be strained off by a sieve such as the kidney seemed 

 to be. 



Borelli, as we have seen, while accepting the old view of 

 animal spirits residing in the brain and nerves, framed a 

 physical mechanical conception of them ; in his eyes the animal 

 spirits became a fluid of peculiar physical features, but still a 

 corporeal fluid, acting in a mechanical way. Sylvius also accepts 

 the animal spirits, but to him they become a chemical fluid, a 

 fluid with chemical properties, a fluid of the type of common 

 alcohol, existing, flowing in a pure state perhaps in the nerves, 

 but capable of mixing elsewhere with the blood. This is seen 

 in his view of the spleen : 



" Since the spleen serves neither for sensation nor mere 

 " movement, it must be for some other purpose that it receives 

 " in such notable quantities the animal spirits (as indicated by 

 "its great nerve supply). For what end can it receive these 

 " except that they may enter into and be intimately mixed with 

 " the inflowing (arterial) blood, and make that blood more subtle 

 " and spirituous than its wont, that is to say, more complete 

 " than the rest of the (arterial) blood which is already perfect, 

 "in other words, more than perfect ?" 



These two men, Borelli and Sylvius, stand out in the middle 

 of the seventeenth century as the founders of two distinct, and 

 indeed contending schools of thought. Borelli sought to explain 

 most, if not all the phenomena of the living body as mere 

 problems of the new mathematical, mechanical, physical science, 

 and so became the founder of the iatro-mathematical school. 

 Sylvius sought to explain the same phenomena as mere 

 problems of the newborn chemical science, and so became the 

 founder of the iatro-chemical school. But the two were men 

 of a very different mould. 



Borelli had a foundation of exact, definite, proved know- 

 ledge to build upon; his mind was a strong and acute one; 

 he himself rarely, if ever went further than facts and his 

 reason led him, save perhaps when he, as all his school are 

 tempted to do, trusted too much to the power of a formula 

 to carry him over gaps where a knowledge of facts waa 

 wanting. He would have been the first to scoff at the handi- 



