PREFACE. is 



ties to pra&ife the art of healing with real advantage to 

 the public ; it would enable every one of literary ac* 

 quirements to diftinguifh the genuine difcipies of medi- 

 cine from thofe of boaflful effrontery, or of wily addrefs $ 

 and would teach mankind in fome important fituations 

 the knowledge of themfehes. 



There arefomemodernpra&itioners,whodeclaimagamft 

 medical theory m general, not confidering that to think 

 is to theorize 5 and that no one can direct a method of 

 cure to a perfon labouring under difeafe without think- 

 ing, that is, without theorizing ; and happy therefore 

 is the patient, whofe phyfician poffefTes the bed theory* 



The words idea, perception, fenfation, recollection, 

 fuggeftion, and alfociation, are each of them ufed in this 

 treatife in a more limited fenfe than in the writers of met- 

 aphyfic. The author was in doubt, whether he mould 

 rather have fubflituted new words inftead of them j but 

 was at length of opinion, that new definitions of words 

 already in ufe would be lefs burthenfome to the memory 

 of the reader. 



A great part of this work has lain by the writer above 

 twenty years, as fome of his friends can teftify : he had 

 hoped by frequent revifion to have made it more worthy 

 the acceptance of the public ; this however his other 

 perpetual occupations have in part prevented, and may 

 continue to prevent, as long as he may be capable of re- 

 vifmg it \ he therefore begs of the candid reader to ac- 

 cept of it in its preferit date, and to excufe any in- 

 vol. *• h accuracies 



