The discovery of a copy (in Lincoln MS 230) of Peter Lombard's lectures on the Sentences in three books (starting with the hexameral discussion that follows the treatise on the angels in the four-book version edited by Brady) makes possible for the first time investigating the development of the Lombard's theological teaching during his Parisian teaching career and the fortuna of that teaching outside of Paris. The fact that the Lombard began his early-career lectures on the Sentences in precisely the same place as he began his lectures on Genesis means that all of his teaching originated with Scripture. Moreover, the fact that Lincoln MS 230 is one of many early copies of the Lombard's Parisian teaching found in English cathedral libraries — Lincoln's Cathedral Library has another manuscript containing another copy of the Sentences, Lincoln MS 31, this one on four books, almost certainly copied within the Lombard's lifetime — has revealed the inadequacy of Brady's edition for scholarly understanding of the Lombard's career and teaching. Until now, no scholar paid much attention to the fact that Brady's choice of manuscripts was largely arbitrary and that his edition reflected the state of the Lombard's text around the time of Bonaventure in the mid-thirteenth century. Thus this discovery makes clear that the Sentences, like Gratian's Decretum and Comestor's History, developed over time. The Sentences were not, as so long assumed, a book written by the Lombard late in his career but rather the product of lectures delivered over the course of his career. The discovery of a treasure trove of English manuscripts preserving the Lombard's earliest extant Parisian teaching will enable scholars for the first time to trace the origins and development of the institutional practices of the cathedral school of Paris right up to the time of its transformation into the University of Paris.