Antiphonal psalmody, after the pattern of that employed at Milan, was introduced into the divine office at Rome by Pope Celestine, who reigned 422-432. It is at about this time that we find indications of the more systematic development of the liturgic priestly chant. The history of the papal choir goes back as far as the fifth century. Leo I., who died in 461, gave a durable organization to the divine office by establishing a community of monks to be especially devoted to the service of the canonical hours. In the year 680 the monks of Monte Cassino, founded by St. Benedict, suddenly appeared in Rome and announced the destruction of their monastery by the Lombards. Pope Pelagius received them hospitably, and gave them a dwelling near the Lateran basilica. This cloister became a means of providing the papal chapel with singers. In connection with the college of men singers, who held the clerical title of sub-deacon, stood an establishment for boys, who were to be trained for service in the pope’s choir, and who were also given instruction in other branches. This school received pupils from the wealthiest and most distinguished families, and a number of the early popes, including Gregory II. and Paul I., received instruction within its walls. By the middle or latter part of the sixth century, the mediaeval epoch of church music had become fairly inaugurated. A large body of liturgic chants had been classified and systematized, and the teaching of their form and the tradition of their rendering given into the hands of members of the clergy especially detailed for their culture. The liturgy, essentially completed during or shortly before the reign of Gregory the Great (590-604), was given a musical setting throughout, and this liturgic chant was made the law of the Church equally with the liturgy itself, and the first steps were taken to impose one uniform ritual and one uniform chant upon all the congregations of the West.