The Rays of Influence of Pierre d’Ailly’s Astrology: Manuscripts, Printed Books, and Their Fifteenth-Century Readers

This article explores the fifteenth-century transmission of astrological works by Pierre d’Ailly (1350–1420). An examination of three incunables, as well as manuscripts of d’Ailly’s writings, illuminates not simply the business calculations of printers in Louvain, Rouen, and Augsburg, but also readers’ various understandings of these texts. Some saw these treatises within a reforming context – one that could include attacks on superstition as well as the correction of the calendar as part of the larger project of Church reform. Others looked to d’Ailly as a source for eschatology, and especially for methods of calculating when the End would come.