Organon §118

Each medicine acts in a unique way. 

Every medicine exhibits particular actions in the human body which do not come about in exactly the same way from any other medicinal substance of a different kind. 157


157 This fact was also perceived by Albrecht von Haller who wrote (in the preface to his Hist. stirp. helv.):  Latet immensa virium diversitas in iis ipsis plantis, quarum facies externas dudum novimus, animas quasi et quodcunque caelestius habent, nondum perspeximus. [A great diversity of strength lies hidden in these plants themselves, whose external features we have long known but whose souls, as it were, and whatever divine element they have, we have not yet perceived.]