Bernhard (b. 1683) and Hieronymus (b. 1685) Pez were born into a family of innkeepers in the small Lower Austrian town of Ybbs on the Danube. That they – as well as their two other brothers, Philipp and Zacharias – chose to pursue an ecclesiastical career was not unusual within the milieu of Austrian or southern German small-town burghers around 1700. Bernhard and Hieronymus attended the Jesuit schools at Krems and Vienna before taking the habit of Benedictine monks in the abbey of Melk. This was one of the most important and influential of the Lower Austrian monasteries of the old orders, which had regained much of their economic and political standing with the Counter-Reformation. Under Abbot Berthold Dietmayr (1700–1739), Melk experienced an intellectual and cultural apogee during the lifetime of the brothers Pez.
In 1709, Bernhard Pez was entrusted with the abbey's library; around this time, he conceived the intention of compiling a comprehensive dictionary of Benedictine authors, which was to be called the "Bibliotheca Benedictina". The aims of this project included both the demonstration of Benedictine learned achievement, particularly in the context of rivalry with the Jesuits who dominated nearly all higher education, and the presentation of ancient and medieval texts as "pure and unadulterated" sources of spirituality in declared competition with the widely prevalent speculative theology of neo-scholasticism.
The learned correspondence of the brothers Pez initially served as a means of gathering material for the "Bibliotheca Benedictina". Soon, however, it developed a dynamic of its own, as Hieronymus began to pursue separate paths of research oriented toward regional and national history, and both brothers became recognised members of the European community of learned men. The information gained from correspondence, and eventually also by travel to numerous monasteries, proved insufficient for the realisation of the "Bibliotheca" in its intended form. The brothers nonetheless published extensive quantities of their accumulated source materials in several voluminous collections; parts of their compilations for the "Bibliotheca" were later used in the four-volume "Historia rei litterariae ordinis sancti Benedicti" by Magnoald Ziegelbauer and Oliver Legipont.
External circumstances also sometimes obstructed the brothers' research efforts: learned controversies with Prefect Gentilotti of the Imperial Library and with the Jesuits Hevenesi and Hansiz, as well as severe disagreements within the monastery pitting Bernhard against Abbot Dietmayr. Bernhard Pez eventually died rather young (1735), while Hieronymus pursued his distinct research interests until his own death (1762).
By the middle of the eighteenth century, the original aims of the brothers – the promotion of positive theology and the defense of Benedictine erudition against Jesuit rivals – were becoming obsolete or being subsumed into other currents of Reform Catholicism, becoming part of what would much later be labelled "Catholic Enlightenment".