NECESSITY FOR EMPIRICAL TREATMENT. 221 



sure that every miss is due to unsteady aim. He must fire 

 high or low, to one side or the other, as he finds necessary, and, 

 by gradually correcting every error, his aim will at last be sure. 

 Should he then be called on to stand sentry on some dark night, 

 and shoot at some suspicious object without hitting it, he would 

 know that his failure was due to his not having seen the object 

 distinctly, and having consequently aimed in a wroug direction. 

 And just as the riHeman, before he stands sentry in the dark, 

 must learn to shoot by daylight, when he can note the effect of 

 each alteration in the position of his ritie on the course of the 

 bullet, so ought we to investigate the action of our remedies in 

 circumstances and under conditions which we know and can 

 vary at will, marking the effect of each variation upon their 

 action tjll we thoroughly and exactly understand what it is, 

 before we proceed to give them in disease, when not only the 

 conditions under which they operate are at present in a great 

 measure unknown, but the effects they produce cannot be 

 definitely ascertained from insufficient knowledge of what the 

 result would have been had they been withheld. Of late years, 

 it is true, vigorous efforts have bce;i made to determine what 

 course diseases run when not interfered with by medicines ; 

 and, although it is often difficult to say what the sequence of 

 symptoms will be in any paiticular case, depending as it does 

 not only on the general course of the disease but on individual 

 peculiarities of the patient and on the varying circumstances 

 in which he is placed, we may nevertheless ascertain with 

 tolerable accuracy whether or not our treatment is beneficial in 

 a general way, even when we cannot determine its effects in 

 detail. 



Very inexact and very unsatisfactory as such a knowledge of 

 medicines as this necessarily is, it must for the present be our 

 guide in practice in a large number of instances ; and our treat- 

 ment at present and for some time to come will be chiefly em- 

 pirical, because our knowledge of pharmacology, and perhaps 

 still more of pathology, is not yet sufficiently advanced. For 

 tliere is hardly any disease in which we know the exact nature 

 of the .morbid changes wiiich are occurring, or the precise organs 

 or tissuec which are their seats ; and, with some excexDtions, we 



