736 THE POPULAR SCIENCE MONTHLY. 



to look carefully at the paintings ? You both see them with your 

 eyes alike. Is it not because behind the eye there is something 

 that is mental which enhances your enjoyment, and the lack of 

 which prevents him from appreciating the beauties of art ? 



Go to a concert, and, as you come away, listen to the comments 

 of people about you. One says that he was occupied chiefly in 

 watching the gyrations of the man who plays the kettle-drums. 

 Another is indulging in raptures over the intricate counterpoint 

 displayed in the orchestration of the symphony. You have en- 

 joyed the music without perhaps having noticed the counterpoint 

 at all. And yet you and the other two have heard equally well, 

 so far as the actual hearing goes. But how differently you have 

 really heard ! It has been the reception of the sounds in the brain, 

 rather than in the ear, the appreciation of their meaning, the ideas 

 awakened by the sensations there, which has determined this dif- 

 ference. You see and hear with the brain, and not with the eye 

 or ear. 



Or take another function of the brain, that of voluntary move- 

 ment. You may be fairly skillful and graceful ; you may have 

 learned to write a good hand, or to play on the piano ; you may 

 even have succeeded in acquiring the power to pronounce foreign 

 languages with the ease and fluency of your own. But this is not 

 the limit to the knowledge of movement. There are many new 

 motions which you might acquire ; for example, the steps of new 

 dances, the peculiar fingering of the violin or cornet or other 

 musical instruments, or some one of the innumerable fine adjust- 

 ments of motion which you see made with such rapidity by any one 

 of fifty different operatives in every factory in the land. All these 

 are movements of adaptation and adjustment, first studied by the 

 aid of sight and then imitated by the aid of muscular sense, or the 

 sense of movement, and finally acquired by practice till they can 

 be executed with dexterity. It is not the fingers or the muscles 

 which have learned the movements. It is the brain which, in its 

 motor area, has received the sensation of movement, has retained 

 a memory, and then combined the memories into new forms of 

 motion so as to direct and guide the hand which carries them out. 

 And so, though we all have hands and arms, there are some who 

 use them deftly and are skillful, and there are others who will 

 always be hopelessly clumsy and awkward. And the difference 

 lies in the brain in the part called the motor area. 



Where are the various areas ? They can be shown by the aid 

 of diagrams representing the brain surface (Figs. 3 and 4). In the 

 middle lies the motor area (Fig. 3, 1), and it is interesting to know 

 that on the left half of the brain, which guides the right hand, it 

 is larger in extent than on the other side which controls the left 

 hand ; because the majority of fine movements are performed by 



