246 MENTAL AND PHYSICAL EXERCISE. 



sary, that not only health, but even life itself depends 

 upon them. 



776. " Laughter" says Dr. Willieh, " is sometimes the 

 effect of joy ; but it frequently arises from a sudden dis- 

 appointment of the mind, when directed to an object, 

 which, instead of being serious and important, terminates 

 unexpectedly in insignificance. Within the bounds of 

 moderation, laughter is a salutary emotion ; for as a deep 

 inspiration of air takes place, which is succeeded by a 

 short and frequently repeated expiration, the lungs are 

 filled with a great quantity of blood, and gradually emp- 

 tied, so that its circulation through the lungs is thus bene- 

 ficially promoted. It manifests a similar effect on the or- 

 gans of digestion. Pains in the stomach, colics, and seve- 

 ral other complaints that could not be relieved by other 

 means, have been frequently removed by this. In many 

 cases, where it is purposely raised, laughter is of excellent 

 service, as a remedy which agitates and enlivens the 

 whole frame. Experience also furnishes us with many 

 remarkable instances where obstinate ulcers of the lungs 

 or liver, which had resisted every effort of medicine, were 

 happily opened and cured by a fit of laughter artificially 

 excited." 



777. In cases, however, where the conscience is against 

 the practice of laughing, little good may be expected 

 from it. 



DIFFERENT KINDS OF MUSCULAR EXERCISE. 



778. There is a great difference, in the amount of ex- 

 ercise which men require, depending very much upon con- 

 stitution and habit. There is also a selection to be made, 

 with respect to adaptation to the mind, since what would 

 prove exhilarating to some, might be mere drudgery to 

 others. Those who require muscular recreation, ought 

 therefore to select such as combine excitement with con- 

 venience; the same being adapted, with respect to its 

 greater or less violence, to the constitution and habits of 

 the individual. 



