958 EFFECTS OF OVER MENTAL EXERTION 



grees of mental culture conjoined with vigorous 

 health, except among individuals of large thorax. 

 Like the bow which loses its elastic force by 

 being long bent, the power of the strongest mind 

 is gradually impaired by intense thinking. And 

 if not relieved by change of scenery and of occu- 

 pation,* exercise in the open air, the occasional 

 use of the warm bath, succeeded by a cold douche, 

 light or agreeable amusements, and the soothing 

 conversation of congenial friends, it falls into a 

 state of melancholy, from which it never recovers ; 

 or is quenched by apoplexy, paralysis, or mad- 

 ness, still more deplorable than premature death. 

 Alas ! how many precious lives have been sacri- 

 ficed by an ardent zeal to benefit mankind ; and 

 some of them while attempting to unfold the 

 laws of physical and moral health. But when 



second year of his age ; notwithstanding the natural vigour of his 

 constitution. Thus it is that the intemperate quest of knowledge 

 often destroys its favourite votaries no less certainly than the de- 

 pressing passions, or excesses in eating, drinking, and many other 

 gross vices. But when science shall have been stripped of mystery, 

 and reduced to the simplicity of established principles, it will be 

 only a healthful and delightful amusement to acquire a knowledge 

 of whatever is essential to happiness. 



* Change of ideas is as necessary to a perfectly sound state of 

 mind, as variety of food to physical health. Great discoveries 

 may be achieved by the cultivation of a particular talent ; but 

 the highest state of mental improvement requires the temperate 

 exercise of all the intellectual faculties and moral sentiments, in 

 such a way as to produce the greatest amount of pleasure without 

 fatigue or satiety, and maintain a due balance of the whole. 

 Otherwise it is impossible to have " mens sana in corpore sano." 



