The PREFACE. xix 



tenth part of the Jifnples in iife^ jo thafy ' 

 of confeqiience ^ writers miifl copy from 

 one another y and report to us many thijigs 

 on tradition* 



WHOKVER is at all acquainted 

 iviththe power of drugs ^ even Jr cm his 

 own experience y knows how extremely 

 dificult It is to af certain their 7nedicinal 

 properties ; as the fame individual me- 

 dicine has difjcrent efecrs, 7iot only i?i 

 different co?2jiitutions, and in different 

 di/eafes, but aljo in different f cages of ' 

 the fame difeafe , Jn fhort^ there are Jo 

 many circumftanceSy to which we either 

 do jiotj^ or perhaps cannot^ fufficiently 

 attend^ which vary their operation and 

 effeSsy that we are frequently dif ap- 

 pointed in our expeBations, even oj thofe 

 7nedicines with which we are heft ac* 

 quainted, 



THE SE ingenious hi?2ts I thought 

 extremely neceffary^ in order to eonvijice 

 gentlemen of the great uncertainty of 

 medic i?ie in general-, to the end that 

 they may not be impofed on by the fuper- 

 ficial rcafonings of farriers in general^ 



b 2 who 



