His
Contra adversarium perfectionis christianae of c. 1269, in support of
William of St Amour, argued that extreme emphasis on poverty contradicted the Aristotelian doctrine of the mean and undermined the basis of pastoral work. It provoked replies from
Thomas Aquinas and
Bonaventure. From the
Franciscan side, Bonaventure wrote
Apologia pauperum, and
John Peckham wrote his
Tractatus pauperis. The
Dominican Aquinas wrote his case on the "state of perfection" in
De Perfectione Vitae Spiritualis contra Doctrinam Retrahentium a Religione (1270). On
trinitarian theology, however, Gerard was much closer to the emerging Franciscan view. With Aquinas, he was one of the developers of the
quodlibet genre of open philosophical discussion, flourishing for about a century from his time. His polemics used a combination of quodlibets and sermons. He was a major benefactor to the
Sorbonne library, leaving it around 300 books and manuscripts; his collection was based on that of
Richard de Fournival, outstanding in Europe in his time. ==Notes==