"This paper explores R. Jacob Emden's surprising quest for the knowledge of alchemy. This important eighteenth-century rabbinic leader searched for ancient books in the library of Göttingen University, sought living experts and read original alchemical works in German. His sustained interest in alchemy reflects an historical phenomenon far deeper than his personal curiosity. By delving into his forgotten 1736 Igeret bikoret, comparing it to his other writings, and then contextualizing it within contemporary European medical discourse, I wish to use the quarrel between competing medical world views, so typical of the early modern era, to understand R. Jacob Emden's alternative, esoteric path to modernity and the specific ties it reveals between theology, law and medical practice."