This study traces the history of the term Reinheit (purity) in German-speaking parts of Europe from Luther to Adelung with reference to its etymology, semantics and the impact it had in that period. The study proceeds from the realization that the crucial problem of Sprachreinheit (language purity) can only be appropriately discussed by going beyond the narrow limits of the so-called Fremdwort approach. Instead, the author develops a more complex view of the subject by situating the rhetorical category of puritas in the theological, language-philosophical, political and social context of the period in question, thus revealing the full rhetorical significance of the term and with it the rich aesthetic and pragmatic implications it had.