THE MEDIAEVAL ATTITUDE 



alchemy, to restore the balance when mind or body 

 suffered from disease. 



Out of a complicated and obscure mass of guesses 

 and conflicting details, we can be certain that life, it- 

 self, was supposed to be bound up with the breath, or 

 spirit. In some way, also, the heart and the brain 

 converted the physical air we breathe into the mys- 

 tical breath of life. In them was created or, at least, 

 maintained this life force which subdivided into 

 vital, natural, and animal spirits. The heart sent out 

 two of these living streams; the natural spirit, or 

 blood, through the veins, and the vital spirit, or air, 

 through the arteries. The brain disseminated the ani- 

 mal spirits by means of the nerves. How these fluids 

 returned to the brain and heart, if they did flow back 

 at all, was not known, but in some mysterious way 

 these spirits passed into the system and nourished and 

 vivified the organism. Before a science of biology 

 could be established this metaphysical idea must be 

 replaced by a form of mechanism which would, at 

 least, push spiritism further into the background. 

 This great step, as I have said, was made by Harvey 

 The first consequences of the discovery of the circu» 

 lation of the blood were quickly discerned; the heart 

 becomes a pump, self-acting to be sure, and the cir- 

 culating blood loses its mysterious properties; as a 

 fluid stream in a net-work of pipes, it bears the nutri- 

 ment to the various parts of the body. The cause of 

 the beating of the heart and of the other so-called 



