in] of the New Physics. 73 



subject by refuting the wrong explanations of muscular con- 

 traction which had been put forward by various authors. 



"Although Nature is admirable in all her operations yet 

 " there is no one who is not in the highest degree astounded 

 " when he considers the immense force and energy of muscles, 

 " and sets about to understand more exactly the causes, organs 

 "and apparatus by which Nature carries out such a work. 

 " And for the reason that human stupidity is more easily struck 

 " with the ugliness of error than with the beauty of truth, 

 " I shall first proceed to expose wrong views, both because this 

 "part of science is not to be despised, and also because the 

 " exclusion of what is erroneous the more easily leads us to the 

 " discovery of what is true." 



The first wrong view which he exposes is the one that 

 muscles are directly moved by some incorporeal agency. 



" Muscles do not exercise vital movement otherwise than 

 " by contracting. Such a violent contraction however is not 

 "brought about by anything else than the hardening and 

 " inflation which the muscle undergoes. Now such an inflation 

 u cannot be conceived without the advent and insinuation of a 

 " second body. For the corporeal mass of the muscle, possess- 

 " ing as it does three dimensions, cannot be inflated and 

 " increased in bulk by any wholly incorporeal influence having 

 " like an indivisible point no magnitude." 



He next refutes the view that muscular movement is 

 brought about by spirits or by a corporeal air, such as the 

 atmosphere is. 



"There are not wanting those who insist that extremely 

 " attenuated corporeal animal spirits like air supply the cause of 

 u the movements of muscles. 



" But these cannot extricate themselves from innumerable 

 " difficulties. For, according to their views that spirituous air 

 "either expands the muscles, rushing into their cavities like 

 " wind, and filling them with its abundance and plenty, or on 

 " the other hand brings about the contraction by filling up the 

 " porosities of the muscles through ebullition and rarefaction. 

 " But this seems to be impossible because the action of a muscle 

 " is a mere contraction of its length, so that the two ends by 



