82 THE EVOLUTION OF MAN 



is the brain with the' animal spirit. By the animal spirit, as 

 the context shows, he meant the capacity to think, to re- 

 member, to reason, and to imagine. All these functions, how- 

 ever, are functions of the brain, and that body of reactions, 

 instincts, and habits that characterizes each individual whereby 

 he may be described as honest or dishonest, cheery or somber, 

 kindly or malevolent, are from this standpoint products of the 

 nervous system. Although this view has been again and again 

 assailed, it has maintained itself to the present time and bids 

 well to remain one of the fundamental facts of biological 

 knowledge. 



Yet to the man on the street personality and all that per- 

 tains thereto remains much as in pre-Vesalian days, a vague 

 general characteristic of the body as a whole and not a 

 feature of one system of its organs. To attempt to persuade 

 him otherwise is more likely to arouse his suspicions than to 

 advance his knowledge. This is particularly true of so simple 

 a matter as sensation. When you prick your skin with a pin 

 nothing seems more natural than to locate the sensation of 

 pain where the pin abraded the skin and yet we know that the 

 sensation of pain is in the cerebral cortex of the brain and not 

 in the skin. The evidence that this sensation is resident in 

 the cortex comes from several sources. First, it is known that 

 if a nerve is cut, the part of the body supplied by that nerve 

 loses sensibility. When a nerve going to a part of the hand is 

 accidentally severed, a pin may be thrust into that part without 

 producing the least sensation whatever, showing that the hand 

 in itself is not endowed with pain. Not until the restoration 

 of the nerve months after the accident does the sensation of 

 the afflicted part return. Not only are there circumstances 

 under which a part may be present though without sensation, 

 but there may be sensations without the presence of any part. 

 This condition is well seen in the so-called phantasmal extremi- 



