FROM THE EARLIEST moments of Christianity, prayer and meditation were required practice for devotees. But how one prayed—and what that meant—was rather unclear. Jesus recommended prayer to his brethren throughout the Gospels, saying things like: “Go to a room by yourself, and shut the door…and do not go babbling on like heathen, who imagine that the more they say the more likely they are to be heard.” But, soon after Jesus’ death, the apostle Paul seemed to contradict Jesus’ words, advising Christians to “pray without ceasing.” The early Church Fathers took Paul at his word in the following centuries, emphasizing, as the third-century Cyprian of Carthage did, that Christians should not just pray the “Our Father,” but rather that “there should be no hour in which Christians do not frequently and always worship God, so that we who are in Christ…ought to be constant throughout the day in petitions and prayer…We who are in Christ—that is, always in the light—ought never to cease from prayer during the night.” Accordingly, Anthony of Egypt, who by many accounts was the third-century founder of Christian monasticism, followed Cyprian's advice, spending “the whole night groaning and lamenting, reflecting on the great number of enemies that humans have and the struggles they must endure against such a great army and their difficult journey through the air to heaven.” Even the earliest instructions about Christian prayer, therefore, remain a vague and contradictory foundation for Christians past and present. What is “babble,” and what distinguishes it from “prayer”? How does one pray unceasingly without “babbling”? What does “worship God” mean? Why is prayer filled with “groaning and lamenting” and not celebration? What is prayer, and how does a good Christian do it?

The answers to these questions varied over Christian time and between distinct Christian contexts, identities, and geographies. But there was never a more intense laboratory for medieval meditation and prayer than the Christian coenobitic monastery, and never a more inventive moment in that laboratory than in the eleventh and twelfth centuries.