He formally became a theologian in 1257 and from then was known as an opponent of the mendicant orders,[1] particularly in the second stage of the conflict,[2] taking part in a concerted attack that temporarily affected their privileges.
[3] 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[4] and undermined the basis of pastoral work.
[7] The Dominican Aquinas wrote his case on the "state of perfection" in De Perfectione Vitae Spiritualis contra Doctrinam Retrahentium a Religione (1270).
[9] With Aquinas, he was one of the developers of the quodlibet genre of open philosophical discussion, flourishing for about a century from his time.
[11] He was a major benefactor to the Sorbonne library, leaving it around 300 books and manuscripts;[12] his collection was based on that of Richard de Fournival, outstanding in Europe in his time.