CLASSICAL ANTIQUITY, MIDDLE AGES 63 



its will, for the whole body exists for the sake of the soul. The human hand 

 is described in detail and with great thoroughness, but, as one can clearly 

 see, as the result of investigating the hands of apes. Then he describes the 

 rest of the extremities and afterwards the intestinal canal, the respiratory 

 organs, the brain, the spine, the blood-vessels, and the genital organs. Galen 

 stands highest as a brain and nerve anatomist, and in this sphere his anatomi- 

 cal and experimental investigations gave results which left all his predeces- 

 sors far behind. He considerably increased the knowledge of the motor and 

 sensory function of the nerves, which the Alexandrine anatomists had already 

 observed, and he differentiated between the sensory, or, in his terminology, 

 the "soft" nerves, and the motor, or "hard." The soft nerves go from the 

 brain to the sense organs, the hard from the spinal marrow; as the nerves of 

 the spinal marrow also show definitely sensible qualities, though Galen did 

 not succeed in discovering the difference between the anterior and the pos- 

 terior medullary nerves, he evades the difficulty by assuming a "mixed" 

 consistency and function in certain medullary nerves. By experiments in sever- 

 ing different sections of spinal marrow in living animals he showed the con- 

 nexion between these and corresponding parts of the body. The brain he 

 likewise described in detail; of its nerves he traces seven couples, the rami- 

 fications of which are closely worked out. On the other hand, his idea of 

 the function of the brain is confused, owing to speculations upon the "soul 

 pneuma," which, produced in the cerebral ventricles, circulates through the 

 entire nervous system and forms its most essential component, the basis of its 

 functions. It may be mentioned in this connexion that he shared the ancient 

 idea of the localization of the various qualities of the soul in various organs, 

 which naturally gives rise to long expositions on the wisdom of the Creator 

 and the finality of the creation. The account of the digestive apparatus and 

 its function is in Galen, as in the anatomists of antiquity in general, one of 

 the weak points. The human digestive canal is described after combining 

 the results of dissections performed on various animals, both vegetarian and 

 carnivorous, which fact does not help to make his idea of it clear. Digestion, 

 which in Aristotle was the result of the cooking of the food, is ascribed by 

 Galen to a special "transformation power" in the stomach; its products are 

 transferred through the blood-vessels to the liver, where they are converted 

 into blood; the useless parts of the food are absorbed by the spleen and con- 

 verted by it into "black bile," which is excreted through the bowel. The 

 kidneys serve to remove excessive water from the blood. This is afterwards 

 conveyed through the veins of the liver, partly to the right chamber of the 

 heart and partly out into the body. 



Heart and blood-vessels 

 Galen described the system of the blood-vessels in detail, and his opinion 

 on this subject — with its errors as well as its merits — had a more lasting 



