At the beginning of his career as a theologian, Martin Luther was deeply rooted in the texts and methods of the late Middle Ages. His earliest theological thinking left traces in his annotations of a number of standard texts of the medieval curriculum, which commanded his interest and study while he lectured in Erfurt in the period 1509 to 1511. A quarter century of research by Jun Matsuura, professor of German language and literature at the University of Tokyo, has produced a significant contribution to Luther studies in this reediting of the Wittenberg reformer's notes on a series of texts, from Anselm, Bonaventura, Augustine, Peter Lombard, William of Ockham and Giorgio Valla. Matsuura's extensive work in German archives has produced an extensive introduction and a helpfully annotated edition of the texts (largely available in century-old editions in the Weimar edition, which Masuura's work has refined and improved). The introduction presents Matsuura's findings and insights on sources on which Luther's study was based; his dating of the manuscripts; a careful accounting of the history of the collection from which they came; and his assessment of Luther's method of handling the texts. Detailed examination of the annotations reveals Luther's text-critical sensitivity. Matsuura also analyses meticulously his use of ancient, medieval and contemporary sources. An extensive bibliography of the works which Luther cited that had appeared in print or were available to him in manuscript supplies users of this volume with an entry of immeasurable value into Luther's intellectual world. A comprehensive bibliography of modern secondary literature also offers support for further research. The annotations are presented with the texts on which they comment, and non-orthographical features (for example, underlining) enhance the reader's access to Luther's interaction with his reading. Both the text-critical apparatus and the explanatory annotations assist the reader in reading of his engagement of the ancient and medieval authors whose works commanded his attention. This volume will elicit new interest in Luther's earliest documentable ventures into the theological arena and serve generations of researchers to come.