METHOD OF STUDY. 421 



that, partly from mistake and partly from design, history, at all 

 times, has in many particulars been absolutely false, we shall, 

 upon the whole, perceive that observation and history afford a 

 very precarious foundation for the practice of physic on an em- 

 piric plan. You know that the advocates of this plan propose 

 that the practice of physic should be, as much as possible, con- 

 ducted by a simple imitation; that is, when a disease occurs, they 

 should, either in their own observation or in the history of those of 

 others, find a case exactly like to the present, and that therefore 

 they should in the present case employ the remedy which had 

 been experienced useful in the former. But if we only consider 

 the number and diversity of diseases, the difficulty of observa- 

 tion, and the fallacy of history, we shall be led to expect what 

 has actually happened, that simple imitation has seldom been 

 practised. 



The empirics themselves foresaw all this, and therefore pro- 

 posed to provide against it by having recourse to Analogy. 

 This proceeds upon a supposition that there is in many dis- 

 eases seemingly different, somewhat of a common nature ; so 

 that the remedies found useful in one of these, may be presum- 

 ed to be useful also in others resembling it. This common 

 nature of diseases the empirics presumed to learn entirely from 

 hence that they had some symptoms in common with each 

 other ; and this supposes the study of a Nosologia methodica. 

 The proceeding must be in this way : Among the concurring 

 symptoms of diseases, we find some more constant, others more 

 accidental, and thus distinguish species from varieties ; and still 

 proceeding farther, we may find that even amongst the symptoms 

 constituting species, there are some more constant than others, 

 and may thereby unite several species into one genus. Now, 

 if we may presume that the treatment of one species of disease 

 is applicable to all those of the same genus, we have a found- 

 ation from an analogy tolerably extensive, and entirely independ- 

 ent of theory. The scheme is probable, but the execution is 

 difficult. The Nosologia methodica required is not yet obtain- 

 ed. What the ancient empirics might contribute to this pur- 

 pose we have not learned. We find that in modern times, till 

 very lately, no attempt was made in this way but by Felix 

 Plater, who, however, did not propose to separate this study 



