*vi INTRODUCTION TO THE 



terning life and its functions. They are arranged into four clafT- 

 es of motions, which form the foundation of all juft nofology and 

 practice, as detailed in the fecond great divifion of the Zoonomia. Vi- 

 tal motions are thus called irritative, fenjhive, Voluntary, and ajfociated, 

 according as the parts of the body in which they exifl are endowed 

 with irritability, fenfalion, volition, or fympathy. This quadruple allot- 

 ment of functions forms a llrong and peculiar character of the follow- 

 ing work. And the diftribution of the almoit endlefs variety of ani- 

 mated phenomena into this fourfold and lucid arrangement, is a clear 

 proof of the discriminating and generalizing mind of the author. 



But in all thefe conditions of the fyitem, whether influenced by the 

 vis infita or the vis nervea, by voluntary or fympathetic energy, the fen- 

 forial powers are fuilained by the unceaiing operation of stimulants. 

 The theory of thefe is contained in the twelfth chapter of the firft part, 

 and exhibits very advantageoufly the doctrine of (limulus, and exert ion t 

 or as it has been more generally called, excitement. 



There is a itriking analogy between thefe fundamental doctrines of 

 Dr. Darwin and thofe contained in Dr. Browns Elements of Medicine. 

 Our author was aware of this, and to guard himfelf againft the impu- 

 tation of having borrowed Brown's ideas without acknowledgment, or 

 of being merely his imitator, he obferves that " the coincidence of 

 " fome parts of this work with correspondent deductions in the Bru- 

 " nonian Elementa Medicince, a Work (with fome exceptions) of great 

 " genius, muft be confidered as confirmations of the truth of the 

 " theory, as they were probably arrived at by different trains of rea* 

 " forting." 



In vefpect to Originality, there is great difficulty in fettling claims* 

 In this cafe however, there is not even a fufoicion that Brown derived 

 any thing from Darwin. Both might indeed have come to fimilar 

 conclufions, by the independent exercife of their reafon, without any 

 communication or inlercourfe. And yet, an impartial obfervcr, prone 

 neither to obloquy nor flattery, would not forfeit his candour in fuf- 

 pecting that a writer of Darwin's acutenefs might have gathered fome- 

 tiling from Brown, who- publiflied fourteen years before him. 



Confidering the Brunonian and Darwinian fyftems as retting upon 

 the fame pillars, it appears to me there may be both uSeSuhieSs and cu- 

 riofity in Searching and digging about the ground on which they (land. 

 In performing this talk, it has been expected there mould be a ftate- 

 ment /hewing how far thefe doctrines of the Scottifh and Englifh phy~ 

 fieians are themfelves novel or modern, or whether they are both of 

 the old School and derived from remote and ancient Sources. 



By deciding in favour of their modernity, it will be likewife expect- 

 ed that a view fliould be given of the Brunonian fyftem, thai it may 

 be compared with the cotemporary doctrines of Cullen and Darwin. 

 Jn this comparifon, it will be found, that Brown's merit is very con- 

 fpicuouS. The three diftinguifhed authors have fmifhed their earthly 

 id they and their writings may now be confidered without 

 iality. To thofe who are curious to trace the progrefs 

 ♦f thefe opi nil -Inch exert Such extenfive dominion over the mind* 



thefe 



