Viii PREFACE. 



(lamped 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 ; which, fo long as it is concerned in compar* 

 tng the eflfential properties of bodies, leads us to many 

 and important difcoveries ; but when with licentious ac- 

 tivity it links together objects, otherwife difcordant, by 

 fome fanciful fimilitude ; it may indeed collect orna° 

 lnents for wit and poetry, but philofophy and truth re«< 

 coil from its combinations. 



The want of a theory, deduced from fuch ftrict anal- 

 ogy, to conduct the practice of medicine j is lamented by 

 its profeffors ; for, -as a great number of unconnected 

 facts are difficult to be acquired, and to be reafoned from, 

 the art of medicine is in many inftances lefs efficacious 

 under the direction of its wifeft practitioners ; and by 

 that bufy crowd, who either boldly wade in darknefs, or 

 are led into endlefs error by the glare of falfe theory, it 

 is daily practifed to the deftruction of thoufands ; add 

 to this the unceafing injury which accrues to the public 

 by the perpetual advertifements of pretended noflrums ; 

 the minds of the indolent become fuperftitioufly fearful 

 of difeafes, which they do not labour under ; and thus 

 become the daily prey of fome crafty empyric. 



A theory founded upon nature, that mould bind to- 

 gether the fcattered facts of medical knowledge, and con. 

 verge into one point of view the laws of organic life, 

 would thus on many accounts contribute to the intereft 

 of focietv. Tt would caoacirate men of moderate abili- 



tJ< 



