A prayer nut is a small-scale boxwood carving containing very detailed depictions of events taken from the lives of biblical figures and saints. These carvings served as instruments of individual piety, that is, for private devotion; they were especially appreciated when located in a surrounding environment, where the knowledgeable viewing of art became a value in itself. It was in the early modern Kunstkammer of the sixteenth and seventeenth century that prayer nuts would have been studied and admired. The publication contains the papers of a colloquium held in 2012 on the occasion of the discovery of a manuscript,with a meticulous seventeenth-century description of a prayer nut that can be identified with the Magdalen prayer nut in the Abegg-Stiftung. The twenty-six colour plates of the prayer nut and the manuscript invite the reader to study not only a master-piece of miniature carving, but also to comprehend an exceptional source of art historiography in the Northern Renaissance.