Unlike Eastern monastic historiography, for which historians have never constructed a coherent narrative, the story of central medieval Latin monasticism once seemed to be simplicity itself. The sixth-century Rule produced at Benedict of Nursia’s Montecassino (RB), which observers likened to Mount Sinai as a source of sacred law, was said to have been quickly adopted in all Western monasteries outside Iberia. However, “the rule came to be far too laxly followed in many Benedictine monasteries, and in 910 the order of Cluny was founded to renew its strict observance.” The efforts of tenth-century monastic reformers associated with Cluny transformed decadent monasteries into observant institutions and guaranteed that the RB “became for three centuries the uncontested source of all European religious life.” Thus, one survey of medieval Western monasticism covered the central Middle Ages in eight pages devoted to “the formation of a Benedictine tradition and the contribution of Cluny.”