The Rule of Saint Benedict is a book of instructions written in 516 by Benedict of Nursia (c. AD 480–550) for the groups of monks living in the individual communities under the supervision of abbots. In the book, St. Benedict opens the principles of the Christian life in a community. The main principle is obedience and the rule of "ora et labora," that is, "pray and work." The primary weapon to strengthen the Christian faith is obedience to the Lord's will. To achieve this, the author offers to establish the "school for the Lord's service," which will teach people the way to salvation. In 73 chapters of the book, Benedict gives detailed instructions on how to regulate the life of a monk in monasteries and alone. Some chapters consider the organizational sides of monastery life, such as assigning deans and summiting official meetings. Other give instruction on how to practice life in faith and grow spiritually. Generally, the book doesn't call upon the formation of any monastic order. It is rather a manual for different independent Christian communities, small groups of two or three people or single wandering monks, guiding them in everyday decisions and helping to organize their lives spiritually.