364 PHYSIOLOGY AND HEALTH. 



vigorous longevity in the pursuits of literature and science. 

 Some ministers, lawyers, arid physicians, have attended to 

 their professional responsibilities until they were even more 

 than fourscore years old. Most of the men whose vigor and 

 usefulness were thus prolonged, manifested great activity of 

 body, as well as energy of mind. Their mental powers were 

 never idle. They were laborious in their vocations, and stood 

 among the foremost as scholars. But with their great labor 

 of the brain they judiciously combined due attention to the 

 other organs and functions, and thus sustained their physical 

 health. 



CHAPTER XI. 



Mental and physical Powers unequal in various Persons. May 

 be equalized by Education. Inequality of mental Powers often 

 increased by Education and Pursuits of Life. Some excel in 

 one Thing and are deficient in others ; in mechanical Arts ; in 

 Morals. Any mental or moral Power may be developed and 

 strengthened. 



841. In some persons, the several systems have originally 

 various degrees of power. The nervous, nutritive, or mus- 

 cular system may be strong and active, while the others are 

 weak and inactive. This inequality may be removed, par- 

 tially or entirely, by judicious training, by exercising and 

 strengthening those which are weak, and allowing the 

 stronger to rest. For this purpose, the young man who has 

 naturally strong and active brain, and weak muscles and 

 digestive organs, needs the exercise of physical labor for his 

 equal development, but is injured by much mental excite- 

 ment ; while, on the contrary, the robust and vigorous, whose 

 brain is sluggish, needs the stimulus of study, and can bear 

 the physical inaction of a student's life. 



842. The inequalities of the mental and moral powers 

 may be removed by a similar principle in education, which 

 exercises and develops the weak, and leaves the stronger 

 faculties more at rest. But, by a mistake in the purposes 



