288 THE HUMAN MECHANISM 



preparation for its reception ; and while it may do good, 

 there is danger that it may do harm. 



In the second place, the exact action of many drugs is 

 only imperfectly understood. In an emergency the physi- 

 cian uses them temporarily, for some effect which he desires 

 to produce, thus tiding over a difficulty. He uses the drug 

 only a few times, at most, and is consequently not greatly 

 concerned about unfavorable attendant effects ; it accom- 

 plishes some needed purpose, and if it does any harm, the 

 organism may be trusted to recover from it. It is very dif- 

 ferent, however, with the habitual use of any drug. The very 

 fact that it gives some new direction to the events taking 

 place within the body means that abnormal conditions of life 

 are being maintained, and we have already learned that 

 abnormal conditions of life are apt to be unhygienic. 



Again, the use of drugs is only too apt to be substituted 

 for the hygienic conduct of life. We may, for example, 

 take drugs to accomplish something which the healthy body 

 should accomplish for itself without outside help. When 

 one drinks a cup of black coffee to facilitate mental work 

 which his fatigued condition would not otherwise allow 

 him to do, he is trying to get from a drug the power which 

 he could and probably should secure by normal sleep. The 

 coffee acts like a whip to a tired horse ; the same work 

 is done as might have been done had the horse been allowed 

 a little rest, but the horse is not as well off when he does 

 the work under the lash as when he does it in a properly 

 rested condition. Similarly, persons suffering from sleepless- 

 ness often take drugs used to produce sleep (hypnotics), 

 and, superficially at least, the sleep thus secured resembles 

 normal sleep; but experience shows that few if any hypnotics 

 can be used for any length of time without bad effects. 

 Here again a drug is being depended upon to do what the 

 normal body should do for itself. Pepsin tablets may be 

 taken to aid digestion, and thereby an attack of indigestion 



