Johannes von Sterngassen, champion of a rigorously scientifically-oriented Thomism and member of the circles of mystics that formed around Meister Eckhardt, is central to the controversy over mysticism and scholasticism. His environment, biography and works have been reconstructed on the basis of a precise analysis of source material, a wide selection of texts, Latin quaestiones and German sermons. The text reveals Sterngassen's philosophical position and verbal power.