In 529, Benedict of Nursia (480–543) wrote a brief set of regulations for the monks who had gathered around him at Monte Cassino, between Rome and Naples. Benedict’s guide for monastic life, known as The Rule of Saint Benedict, came to influence all forms of organized religious life in the Western Christian Church. Men and women in monastic houses all followed sets of rules, first those of Benedict and later those written by other individuals. Because of these rules, men who lived a communal monastic life came to be called regular clergy, from the Latin word regulus (rule). Priests and bishops who staffed churches in which people worshipped and who were not cut off from the world were called secular clergy.

The Rule of Saint Benedict outlined a monastic life of regularity, discipline, and moderation in an atmosphere of silence. Each monk had ample food and adequate sleep. The monk spent part of each day in formal prayer, which consisted of chanting psalms and other prayers from the Bible in the part of the monastery church called the choir. The rest of the day was passed in manual labor, study, and private prayer. The monastic life as conceived by Saint Benedict struck a balance between asceticism (extreme material sacrifice, including fasting and the renunciation of sex) and activity. It thus provided opportunities for men of entirely different abilities and talents—from mechanics to gardeners to literary scholars. The Benedictine form of religious life also appealed to women because it allowed them to show their devotion and engage in study. Benedict’s twin sister Scholastica (480–543) adapted the Rule for use by her community of nuns.

Benedictine monasticism also succeeded partly because it was so materially successful. In the seventh and eighth centuries, monasteries pushed back forests and wastelands, drained swamps, and experimented with crop rotation. Benedictine houses thus made a significant contribution to the agricultural development of Europe.

Monasteries also conducted schools for local young people, and monks and nuns copied manuscripts, preserving classical as well as Christian literature. Local and royal governments drew on the services of the literate men and able administrators the monasteries produced.