 Father Fidelis of Fanna says (on the "Summa") that no subject is to be found so frequently in manuscripts of the 13th and 14th centuries in the many European libraries he searched.There also exist "summae" on the virtue, vices, the articles of the faith, and the ten commandments; many biblical commentaries; sermons, and disputed questions on grace and other theological topics.John was among those who declared against the general lawfulness of plurality.