INTRODUCTION. X» 



that tliey were benevolently endowed by natufe with 

 their nauseous flavor to warn us against the danger 

 of using theni*too freely. 



A physician might as rationally assert, that it is 

 possible for him to give to the rotation of the earth 

 any direction he w/Z/s, as that the remedies he admi- 

 nisters in accordance with the mere custom of the 

 profession, must infallibly prove beneficial. He can- 

 not dictate laws to Nature in either cas« ; experi- 

 ence alone is the teacher and- arbiter, and on experi- 

 ence must we ground our hopes. But, as hope often 

 deceives us ; and as even the most skilful physician is 

 not infalhble ; the grand rule to be adopted is — "^// 

 strong doses to be avoided^ and such only to be ad- 

 ministered as, though they may not benefit, yet, cannot 

 do any harm." This rule may easily be followed, if 

 we acquaint ourselves with the effects of medicines 

 both in large and minute doses ; and I think, that 

 without this knowledge, no physician can prescribe 

 any remedy whatever, with a clear conscience. Th€ 

 point to which I devoted the greatest attention in my 

 investigations, was — observing the effects produced 

 by various medicines ; and it was not until the opera- 

 lion of a prescription had been thoroughly tested, 

 that I feh confidence in prescribing it in similar 

 cases — similia similibus. 



The ancients, without being acquainted with the 

 natural law of similia similibus curantur ( according 

 to which small doses are required) were well aware of 

 the injurious effects of large doses, and recommended 

 the greatest caution — Praestat pauca dost, et per in- 

 tervalla remedia exhibere, quam uno impetu ventri- 

 culum remediorum tnoleste obruere \ i. e , " it is better 

 to give a medicine in small doses, and at intervals, 



