The Prologue to Bishop Ivo of Chartres' Decretum and Panormia has long been recognized as a seminal text in medieval canon law. It can be called fairly the first extended treatment of ecclesiastical jurisprudence. This treatise on the tension between rigor and mercy in judgment--and how they could be reconciled through dispensation--spoke not only to legal and theological concerns of the early twelfth century but also to enduring questions about the nature and limits of ecclesiastical law.