A foreword subsequently added by Mabillon used the lives of the saints in order to illustrate the history of the early Middle Ages.

In 1681, prompted by the doubts raised by the Jesuit Daniel van Papenbroek over the authenticity of supposed Merovingian documents held at the Abbey of Saint-Denis, Mabillon published his De re diplomatica.

[3]This work brought Mabillon to the attention of Jean-Baptiste Colbert, who offered him a pension (which he declined), and King Louis XIV.

He began to travel throughout Europe, to Flanders, Switzerland, Germany, and Italy, in search of medieval manuscripts and books for the royal library.

Some of the less scholarly monks in Mabillon's own abbey criticized his Lives for being too academic; while Armand de Rancé, Abbot of La Trappe, declared that he was breaking the rules of his Order by devoting his life to study rather than manual labour.

[4] He also caused trouble by denouncing the veneration of the relics of "unknown saints", wrote a controversial critique of the works of St. Augustine of Hippo, and was accused of Jansenism, but at all times he was supported by the king and the Church.

In 1701 Mabillon was appointed by the king as one of the founding members of the Académie des Inscriptions et Belles-Lettres, and in 1704 a supplement to De re diplomatica was published.