There is, therefore, no other possible way in which the peculiar effects of medicines on the health of individuals can be accurately ascertained – there is no sure, no more natural way of accomplishing this object, than to administer the several medicines experimentally, in moderate doses, to healthy persons, in order to ascertain what changes, symptoms and signs of their influence each individually produces on the health of the body and of the mind; that is to say, what disease elements they are able and tend to produce1, since, as has been demonstrated (§§ 24-27), all the curative power of medicines lies in this power they possess of changing the state of man’s health, and is revealed by observation of the latter.
1 Not one single physician, as far as I know, during the previous two thousand five hundred years, thought of this so natural, so absolutely necessary and only genuine mode of testing medicines for their pure and peculiar effects in deranging the health of man, in order to learn what morbid state each medicine is capable of curing, except the great and immoral Albrecht von Haller. He alone, besides myself, saw the necessity of this (vide the Preface to the Pharmacopoeia Helvet, Basil, 1771, fol., p.12); Nempe primum in corpore sano medela tentanda est, sine peregrina ulla miscela; odoreque et sapore ejus exploratis, exigua illiu dosis ingerenda et ad ommes, quae inde contingunt, affectiones, quis pulsus, qui calor, quae respiratia, quaenam excretiones, attendum. Inde ad ductum phaenomenorum, in sano obviorum, transeas ad experimenta in corpore aegroro, etc. But no one, not a single physician, attended to or followed up this invaluable hint.