PREFACE. 



JL H E purport of the following pages is an en- 

 deavour to reduce the fab 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 unfortu- 

 nately for the inquirers into the knowledge of 

 difeafes, that other fciences had received improve- 

 ment previous to their own ; whence, inttead of 

 comparing the properties belonging to animated na- 

 ture with each other, they, idly ingenious, bufied 

 themfelves in attempting to explain the laws of life 

 by thofe of mechanifm and chemiftry ; they confi- 

 dered the body as an hydraulic machine, and the 

 fluids as palling through a feries of chemical changes, 

 forgetting that animation was its eflential charac- 

 teriftic. 



The great CREATOR of all things has infinitely 

 diverfified the works of his hands, but has at the 

 fame time (lamped a certain fimilitude on the fea- 

 tures of nature, that demonftrates to us, that the 

 'whole is one family of one parent- On this fimilitude i$ 

 founded ail rational analogy ; which, fo long as it 

 is concerned in comparing theeffemial properties of 

 bodies, leads us to many and important difcoveries ; 

 but when with licentious activity it links together 

 objects, otherwife difcordant, by fome fanciful fimi- 

 litude 5 it may indeed colled ornaments for wit 



B and 



