426 INTRODUCTORY LECTURES. 



gy. There is great reason to doubt if the general princi- 

 ple upon which the whole plan of analogy is founded, be solid 

 and just, that is, whether the treatment applicable to one 

 species of disease be also applicable to every other species 

 of the same genus, or even whether the treatment applicable 

 to a species is also applicable to the same species under all 

 its varieties. It is indeed true, that, upon a purely empiric 

 plan, this principle is the only one that can guide us upon the 

 occasion of a new variety or species presenting itself, and it may 

 be taken as a guide where we have no better ; but every empiric 

 must acknowledge that it is extremely fallacious. Dr. Syd- 

 enham is the only physician who has employed this empirical 

 analogy to any purpose; but at the same time he has expressed 

 his sense of its fallacy in the strongest manner. He has ex- 

 pressly told us that every new Epidemic required a particular 

 treatment, not to be learned from any analogy, but by particu- 

 lar experience. Indeed both experience and theory concur in 

 rendering the principle of empirical analogy extremely doubt- 

 ful ; and to conclude, however the empirics may boast of the 

 general use of their analogy, it is sufficiently obvious that it can 

 never be of certain application, till, by many and repeated ob- 

 servations, every case shall be brought to be nearly a case of 

 simple imitation : and hence analogy is involved in all the dif- 

 ficulties, exposed to all the fallacies, and liable to all the im- 

 perfections of imitation. 



I proceed now to my third argument, which is to show that 

 any attempt which has been made to teach physic upon a 

 purely empiric plan has been hitherto fruitless, and, in some in- 

 stances, pernicious. Sydenham seems to have made an attempt 

 in this way, and, so far as he goes, he is truly useful ; but he 

 goes but a small way only, and is far short of the demands for 

 practice. But I would say farther, that I deny that Syden- 

 ham proceeds upon an empiric plan. His " Processus Integri" 

 may seem to be such ; but whoever looks into his larger work, 

 must perceive that it was the result of dogmatic studies and 

 conclusions. But it is not necessary to say more on this sub- 

 ject, for his practical conclusions are adapted to particular 

 cases, or to cases only a little generalized; he is far from aiming 

 at a system, and, as I have said, falls very far short of it ; so 



