Johann Valentin Andreae is considered one of the most important theologians from Württemberg of the 17th century. Also he at least inspired if not authored the so-called Rosenkreuzer manuscripts. Martin Brecht paints the complex path this Lutheran theologian took and highlights his writings and his pastoral work. In addition, Brecht studies the relationship of Andreae to Duke August of Braunschweig-Wolfenbüttel, with whom he was closely associated. This biography underscores Andreae’s originality, creativity, and intellectual richness, and thus also contributes to our understanding of the history of the 17th century in Germany.