PREFACE. 



THE purport of the following pages is an endeavour 

 to reduce the fads belonging to ANIMAL LIFE into 

 clafles, orders, genera, and fpecies ; and, by comparing 

 them with each other, to unravel the theory of difeafes. 

 It happened, perhaps unfortunately for the inquirers in- 

 to the knowledge of difeafes, that other fciences had re- 

 ceived improvement previous to their own ; whence, in- 

 ftead of comparing the properties belonging to animated 

 nature with each other, they, idly ingenious, bufied them- 

 felves in attempting to explain the laws of life by thofe 

 of mechanifm and chemiftry ; they confidered the body 

 as an hydraulic machine, and the fluids as paffing through 

 a feries of chemical changes, forgetting that animation 

 was its eflential charaderiftic. 



The great CREATOR of all things has infinitely diver- 

 fified the works of his hands, but has at the fame time 

 ftamped a certain fimilitude on the features of nature, 

 that demonftrates to us, that the whole is one family of 

 one parent. On this fimilitude is founded all rational 



analogy ; 



