120 BENEFICIAL EFFECTS OF MUSCtJLAR EXERCISE. 



for a short time, and think that, if a walk of half a 

 mile does them good, one of a whole mile will do 

 more ; and when they suffer from the error, they 

 shelter their ignorance under the general assump- 

 tion that exercise does not agree with them ! And 

 the same persons who argue thus would think 

 themselves entitled to laugh at the Irishman who, 

 finding himself relieved by five pills taken at night, 

 inferred that he would necessarily be cured if he 

 took the whole box full at once, and on doing so 

 narrowly escaped with his life. 



From these principles it follows, first, that, to be 

 beneficial, exercise ought always to be proportioned 

 to the strength and constitution, and not carried 

 beyond the point, easily discoverable by experience, 

 at which waste begins to succeed nutrition, and ex- 

 haustion to take the place of strength : secondly, that 

 it ought to be regularly resumed after a sufficient 

 interval of rest, in order to ensure the permanence 

 of the healthy impulse given to the vital powers 

 of the muscular system : and, lastly, that it is of the 

 utmost consequence to join with it a mental and 

 nervous stimulus. Those who go out only once in 

 four or five days are always at work but never advan- 

 cing ; for the increased action induced by the pre- 

 vious exercise has fully subsided long before the 

 succeeding effort is begun : and so far as increased 

 nutrition and greater aptitude for exertion are con- 

 cerned, no progress whatever is made. 



