500 INDUCTION. 



We shall select for this purpose a case which as yet furnishes 

 no very brilliant example of the success of any of the three 

 methods, but which is all the more suited to illustrate the 

 difficulties inherent in them. Let the subject of inquiry be, 

 the conditions of health and disease in the human body ; or 

 (for greater simplicity) the conditions of recovery from a given 

 disease ; and in order to narrow the question still more, let it 

 be limited, in the first instance, to this one inquiry : Is, or is 

 not some particular medicament (mercury, for instance) a 

 remedy for the given disease. 



Now, the deductive method would set out from known 

 properties of mercury, and known laws of the human body, 

 and by reasoning from these, would attempt to discover 

 whether mercury will act upon the body when in the morbid 

 condition supposed, in such a manner as to restore health. 

 The experimental method would simply administer mercury in 

 as many cases as possible, noting the age, sex, temperament, 

 and other peculiarities of bodily constitution, the particular 

 form or variety of the disease, the particular stage of its pro- 

 gress, &c., remarking in which of these cases it produced a 

 salutary effect, and with what circumstances it was on those 

 occasions combined. The method of simple observation would 

 compare instances of recovery, to find whether they agreed in 

 having been preceded by the administration of mercury; or 

 would compare instances of recovery with instances of failure, 

 to find cases which, agreeing in all other respects, differed 

 only in the fact that mercury had been administered, or that 

 it had not. 



7. That the last of these three modes of investigation 

 is applicable to the case, no one has ever seriously contended. 

 No conclusions of value on a subject of such intricacy, ever 

 were obtained in that way. The utmost that could result 

 would be a vague general impression for or against the efficacy 

 of mercury, of no avail for guidance unless confirmed by one 

 of the other two methods. Not that the results, which this 

 method strives to obtain, would not be of the utmost possible 

 value if they could be obtained. If all the cases of recovery 



