St. Ambrose, who introduced the chant into Milan, permitted women to join in the chanting of the Psalms, a custom which degenerated in some churches into the establishment of female choirs; though this abuse was prohibited by many popes and councils. Everywhere the bishops encouraged the cultivation of the chant, and Fortunatus describes St. Germanus of Paris presiding in the apse of the Golden Church, and directing the singing of his two choirs. But, as St. Augustine remarks in one of his letters, no uniformity existed among the different churches, and both variations and corruptions were introduced according to the genius of different nations. Hence, the reformation of the Cantus, and the establishment of some uniform standard based on the ancient models, had engaged the attention of several popes before the time of St. Gregory, and particularly of St. Gelasius and St. Damasus. St. Gregory completed their work: he collected in his Centon, or Antiphonary, all the ancient fragments still existing, corrected and arranged them with his own pen, and added some original compositions, bearing the same character of majestic simplicity with the venerable melodies on which they were formed. And finally, to secure the permanence of these reforms, and to extend the use of the ecclesiastical chant throughout the Church, he founded a school which, three centuries later, still survived and flourished. “After the manner of a wise Solomon,” says John the Deacon, “being touched by the sweetness of music, he carefully compiled his _Centon_ or Antiphonary of chants, and established a school of those chants which had hitherto been sung in the Roman Church, and built for this purpose two houses, one attached to the Church of St. Peter the Apostle, and the other near the Lateran Patriarchium, where, up to this day, are preserved, with becoming veneration, the couch whereon he was accustomed to rest when singing, and the rod with which he was wont to threaten the boys, together with the authentic copy of his Antiphonary.”