 Peter Lombard’s Sentences was by far the most successful instance of the form. Commenting on it became an academic requirement for the master of theology in the 13th century, a status it retained until the later 15th century, with new commentaries still appearing in the 18th (Silano 2007, xxx). (The nature of these commentaries varies quite a bit, early commentaries tending to be line by line glosses, and later ones more often a series of quaestiones on more or less selected topics raised by Peter. See Evans 2002 and Rosemann 2009.) Though Peter claims in his prologue merely to have made a collection of the views of Church Fathers and most historians have taken him at his word, his advance lies in the organization of particular questions into a unified plan, based on Augustine’s distinction between things to be enjoyed (God alone) and things to be used (everything else). Secondly, Peter offers his own responses to questions, engages and refutes the opinions of contemporaries when necessary, and in many cases, uses the form to articulate, justify, and create a consensus view. Besides giving theology an organization and making a place for all questions to be considered, Peter often explicitly leaves some questions open. Peter thus invites others to join in the debate and conversation rather than simply accept or reject his views. All of these features made his work especially fruitful for later commentary. Further, Peter Lombard, unlike Abelard, attempted to give substantive and metaphysically based rather than merely verbal solutions to theological problems, a method more in tune with the 13th century curriculum focused on Aristotle, than the 12th, organized around the trivium arts, also positioning Peter’s Sentences for the preeminence it achieved in the 13th century.