242 HUMAN PHYSIOLOGY CHAP. 



energy to devote to things not related to his own work, 

 and therefore all his interests are likely to become 

 centered in his own business. The same is true of the 

 professional man. Unless a person gets a broad and 

 liberal education, which trains and develops the whole 

 brain, in youth and early manhood, he will not have a 

 wide range of sympathies and interests in later life. 

 Herein lies much of the value of a high school and 

 college education. 



166. Habit. If a piece of paper is folded once, it 

 will be impossible to remove the crease, and the paper 

 will tend to fold in the same way again. The coat or 

 dress sleeve will soon become wrinkled so that it is 

 impossible to press the wrinkles out ; they all reappear 

 when the garment is put on. No one can wear your 

 old shoes, for they have become fitted to your feet and 

 cannot fit anybody else. If a young gourd be put into 

 a bottle and allowed to grow, it will take on the shape 

 of the bottle, whatever that may be, and will always 

 retain that form. A young growing tree may be bent 

 in any way, and in time it assumes that shape. " As 

 the twig is bent so the tree is inclined." 



These examples illustrate an important principle that 

 shows itself on every hand, and is known as the law of 

 habit. This law applies to animal life as well, and man 

 is no exception. There are two principles of this great 

 law to be remembered. First, habits are most easily 

 formed in early life, as in the young plant, and in 

 childhood and youth. At this time the tissues are most 

 easily bent and fashioned because they are still plastic. 



