PREFACE. vii 



make a part of the materia medica ; 

 whilft others are found perfedly in- 

 nocent, which they had defcribed as 

 poifonous in their nature. It is hap- 

 py for men when they increafe their 

 knowledge by an obfervation of fadls, 

 and no longer receive impHcitly the 

 traditions of ignorant ages. 



But it is ufual for thofe who find 

 they have been miiled, to give them* 

 felves up too much to doubt. Thus 

 more than is true has been faid of 

 the virtues of plants, and now per- 

 haps lefs than is true is beHeved. It 

 was found that the writings of bota- 

 nifts were largely fuppUed with mif- 

 takes ; and amidft the crowd of er- 

 rors which flood ready to miflead 

 him, the unexperienced praditioner 

 did not know what he might fafely 

 A 4 truft 



