Medicinal actions must be studied by observing what alterations of condition are brought forth in healthy persons by moderate amounts of single medicines.
Therefore there is no other possible way to unerringly experience the peculiar actions of medicines upon the human condition-there is no single, surer, more natural arrangement for this intent than to administer each single medicine experimentally, in a moderate amount, to healthy persons in order to learn what alterations, symptoms and signs of its impinging action each medicine particularly brings forth in the condition of body and soul, that is, what disease elements each medicine is able to and tends to arouse. 151 As has been shown (§24-§27), all of a medicine's curative power lies in its power to alter the human condition; this is illuminated from observation of the human condition.
151 As far as I am aware, not one single physician in the past 2500 years came upon this so natural, so absolutely necessary, sole genuine test of the pure, peculiar tunement-altering actions of medicines upon the human conditon in order to learn what disease states each medicine is capable of curing, except the great and immortal Albrecht von Haller. In the preface to his Pharmacopeia (Basel, 1771, p. 12 fol.), he states: Nempe primum in corpore sano medela tentanda est, sine peregrina ulla miscela; odoreque et sapore ejus exploratis, exigua illius dosis ingerenda et ad omnes, quae inde contingunt, affectiones, quis pulsus, qui calor, quae respiratio, quaenam excretiones, attendendum. Inde ad ductum phaenomenorum, in sano obviorum, transeas ad experimenta in corpore aegroto, etc. [In truth a remedy must first be tried on a healthy body without any foreign admixture. Once one has tested its odor and taste, one should take a small portion of the dose and pay attention to any effects which ensue: what are the pulse rate, the temperature, the respiration rate, the excretions. After observation of the succession of clear effects in a healthy body, one may proceed to trials on a sick one, etc.] Though not a practicing physician, he alone besides me saw the necessity of doing this, but nobody, not one single physician, paid attention or followed these, his inestimable hints.