See his complete works (ed. by H. B. Wright and M. K. Spears, 1959); biography by C. K. Eves (1939, repr. 1972).
With the Cluniac reform the term Prior received a specific meaning; it supplanted the provost (praepositus) of the Rule of St. Benedict. In the congregation of Hirschau, which arose in Germany in the eleventh century, the term Prior was also substituted for Provost, and the example of the Cluniac and Hirschau congregations was gradually followed by all Benedictine monasteries, as well as by the Camaldolese, Vallombrosians, Cistercians, and other offshoots of the Benedictine Order.
The claustral prior (Latin prior claustralis), in a few monasteries called dean, holds the first place after the abbot (or grand-master in military orders), whom he assists in the government of the monastery, functioning effectively as the abbot's second-in-charge. He has no ordinary jurisdiction by virtue of his office, since he performs the duties of his office entirely according to the will and under the direction of the abbot. His jurisdiction is, therefore, a delegated one and extends just as far as the abbot desires, or the constitutions of the congregation prescribe. He is appointed by the abbot, generally after a consultation in chapter with the professed monks of the monastery, and may be removed by him at any time. In many monasteries, especially larger ones, the claustral prior is assisted by a subprior, who holds the third place in the monastery. In former times there were in larger monasteries, besides the prior and the subprior, also a third, fourth and sometimes even a fifth prior. Each of these was called circa (or circator), because it was his duty to make the rounds of the monastery to see whether anything was amiss and whether the brethren were intent on the work allotted to them respectively. He had no authority to correct or punish the brethren, but was to report to the claustral prior whatever he found amiss or contrary to the rules. In the Congregation of Cluny and others of the tenth, eleventh and twelfth centuries there was also a greater prior (prior major) who preceded the claustral prior in dignity and, besides assisting the abbot in the government of the monastery, had some delegated jurisdiction over external dependencies of the abbey. In the high days of Cluny, the abbot was assisted by a coadjutor styled Grand-Prior (Grand-prieur in French).
The conventual prior (Latin prior conventualis) is the independent superior of a monastery that is not an abbey (and which is therefore called a "priory"). In some orders, like the Benedictine, a monastery remains a priory until it is considered stable enough and large enough to the elevated to the rank of an abbey. In other orders, like the Carthusians, conventual priors are the norm and there are no abbots. Their prior general is the only superior of an order who does not reside in Rome. Before their suppression in France, the prior of the mother house Grande Chartreuse was always prior general, an office now filled by the prior of Farneta near Lucca in Central Italy.
An obedientiary prior heads a monastery created as a satellite of an abbey. When an abbey becomes overly large, or when there is need of a monastery in a new area, the abbot may appoint a group of monks under a prior to begin a new foundation, which remains a dependency of the mother abbey until such time as it is large and stable enough to become an independent abbey of its own. A provincial prior is head of an area of certain orders, nortably the Dominicans, who are not monks but mendicants. A convent, male or female, of Dominicans may be headed by a conventual prior, the province by a provincial prior, but the head of the whole order is not called prior general, but master general.
In all these orders the second superior of a monastery is called subprior and his office is similar to that of the claustral prior in the Benedictine Order.