x] of the Nervous System. 285 



" movement undetermined, since neither by sure reasoning nor 

 " by experiment has it been ascertained whence it comes, 

 "whither it tends, where on its departure it betakes itself. 

 ***** 



"There remains another difficulty of no less moment not 

 " yet cleared up, namely in what respect the movement of the 

 " fluid in a muscle while it is contracting differs from the 

 "movement of the fluid in the same muscle when it remains 

 " quiet, uncontracted. Is its quantity changed ? or does it 

 " remain the same ? Is the fluid after the event, supposing it 

 " remains, the same as before the event ? Does the fluid move 

 "because the muscle contracts, or does the contraction of the 

 " solid proceed from the movement of the fluid ? " 



This singular man had three hundred years ago pierced into 

 questions which are still moving us at the present day. 



Since this is the last occasion which I shall have to speak of 

 Stensen, I may here venture to quote his appeal on behalf of 

 the value of science in practical matters : 



"It may be shewn abundantly elsewhere how much medical 

 "practice owes to the anatomical experiments of this age, even 

 " if it were only for this that they have exposed the numerous 

 " errors which occur in the explanation of the causes of disease 

 " and at the same time shewn the reasons which have governed 

 " the application of remedies to be in most cases erroneous. 

 " To those who decry the value of science I would give as an 

 " answer this demand that they should ask their own consciences 

 " and see what solid basis there is for all those dogmas which 

 " they pronounce with such bold ease when they explain the 

 " symptoms of apoplexy, paralysis, convulsions, prostration of 

 " strength, syncope, and other diseases affecting animal move- 

 " ments, on what foundation they rest when they apply remedies 

 " for removing these evils, with the result that they do away 

 " not with the paralysis, not with the convulsion, but with the 

 " paralytic or the convulsed man." 



Willis was very far from reaching the exact standpoint of 

 Borelli and Stensen ; he explains muscular contraction in a 

 very different way. This is what he says : 



" The animal spirits carried from the brain by the channels 



