A rare survival provides unmatched access to the theology classroom of 1330-31. That year, the Franciscan theologian, William of Brienne, lectured on Peter Lombard's Sentences and disputed with the other theologians at the University of Paris. The original, official notes of these lectures and disputes survives in a codex at the Prague National library, and they constitute the oldest-known original record of an entire university course. Building on an analysis of the codex, this study reconstructs the reality of teaching at the University of Paris in the fourteenth century, delineating the pace and organization of lectures within the school and the debates between the schools. The codex, containing a transcription made in William's classroom and a series of modifications and additions made afterwards, provides a unique view on the genesis of the major vehicle for Scholastic thought, the Sentences commentary. This codex shows how a follower of the teachings of John Duns Scotus (+1308), William of Brienne, constructs Scotist doctrine and defends it from within and without in a critical and controversial period in the history of philosophy.