370 PHYSIOLOGY AND HEALTH. 



with few difficulties, and always overcome them. They are, 

 therefore, the most successful and the happiest men. 



856. If all the mental faculties are faithfully cultivated 

 and exercised, the mind acquires its greatest strength and 

 power of universal application. But one thing more is 

 wanting ; that is, the power of concentrating the whole men- 

 tal energies upon a single subject, to the exclusion of all 

 others; that is, the power of the will over all the physical 

 organs, over the instincts, and the passions, and the mental 

 faculties. 



857. This mental discipline subdues not only all the phys- 

 ical and moral, but the mental powers, to the control of the 

 will, and enables us to concentrate the whole force of the 

 nervous system upon one object, and exclude all others ; 

 otherwise, the mind is frequently wandering from the sub- 

 ject proposed to it. The possession or want of this control 

 of the mind this power of concentration constitutes one 

 great difference between the strong and the weak mind 

 the rapid and the dull scholar. 



858. It is the misfortune of many students that, while 

 they fix their eyes upon their books, their thoughts are afar 

 off, upon their play, their home, or their pleasures. They 

 look upon their lessons in school ; their eyes run over a page 

 of history at home ; every line, every word, is presented to 

 the organ of vision ; but no sensation is excited in the brain, 

 the mind receives no ideas. Another, with better mental 

 discipline, withdraws his mind from all but the subject before 

 him ; and, while he is reading or studying, he thinks of 

 nothing else, all other thoughts are excluded, and his 

 whole mental force is directed to the matter about which he 

 is reading; and thus he loses no time, and wastes no mental 

 effort. Every exertion aids him in his advancement, and he 

 is therefore a successful scholar. 



859. The brain has the same desire and enjoyment of 

 exercise as the muscles. The child runs and plays, and 

 observes and talks; and the man, if he has no occasion for 

 motion, will walk for exercise ; and, if he has no call for 



