The Opus pacis, a manual for Carthusian copyists and correctors of Latin manuscripts, was written in 1417 by Oswald de Corda, Bavarian-born vicar of the Grande Chartreuse; it is the earliest known example of an attempt to formulate principles of textual emendation. Although the Opus pacis includes discussions of orthography, etymology, and grammar, it focuses on the practical dilemmas of scribes faced with variant spellings, accents, and pronunciations. The twelve surviving manuscripts of the treatise testify to its popularity throughout the fifteenth and early sixteenth centuries: it circulated also outside the Carthusian Order (to the Cologne Crosiers, the Cologne Brethren of the Common Life, the Benedictines of St. Matthias in Trier, and the reforming bishop, Nicholas of Cues) and inspired the compilation of similar handbooks in other religious orders (the Windesheim and Bursfeld Congregations). This thesis offers the first complete critical edition of the text and description of the manuscripts, two of which are autographs. The accompanying study examines the Carthusian tradition of textual uniformity, the biography of Oswald de Corda, the sources and structure of the Opus pacis, and the use and influence of the work within and outside the Carthusian Order. The study concludes by showing how Carthusian piety fundamentally inspired and encouraged these monks' concern for uniformity. Although the attitude of reverence toward the written word could inhibit criticism of sacred texts, the Opus pacis, recommends judicious emendation and looks forward to the work of Erasmus and other religious humanists of the sixteenth century. Languages: Latin.