xvi INTRODUCTION TO THE 



cerning life and its functions. They are arranged into four claff- 

 es of motions whicli 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, fenjiti<ue , voluntary , and affocnated^ 

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

 with irritability > fenfation volition, Q\' fympathy. This quadruple allot- 

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

 ing work. And the difrribution of the almoft endlefs variety of ani- 

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

 proof of the difcriminating and generalizing mind of the author. 



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

 vts Injita or the vis ner<uea^ by voluntary or fympathetic energy, the fen- 

 forial powers are fuftained by the unceafing operation of STIMULANTS. 

 The theory of thefe is contained in the twelfth chapter of the firftpart, 

 and exhibits very advantageoully the doctrine of ftimulus and exertion^ 

 or as it has been more generally called, excitement. 



There is a finking analogy between thefe fundamental doctrines of 

 Dr. Darwin and thofe contained in Dr. Brown's 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 correfpondent deductions in the Bru- 

 " nonian Elementa Medicinae, 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- 

 " foning " 



In refpect to originality there is great difficulty in fettling claims. 

 In this cafe however, there is not even a fufpicion 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 intcrcourfe, And yet, an impartial obferver, 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- 

 thing from Brown, who publifhed fourteen years before him. 



Confidering the Brunonian and Darwinian fyftems as refting upon 

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

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

 In performing this taik, it has been expected there fhould be a ftate- 

 inent mewing how far thefe doctrines of the Scottifh and Englifh phy- 

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

 the old fchool and derived from remote and ancient fources. 



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

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

 be compared with the cotemporary doctrines of Cullen and Darwin. 

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

 fpicuous. The three diflinguiflied authors have finifhed their earthly 

 career, and they and their writings may now be confidered without 

 envy or partiality. To thofe who are Curious to trace the progrefs 

 of thefe opinions, which exert fuch extenfive dominion over the mind, 



thefe 



