IV.--Walafrid Strabo (807-849). _De Ecclesiasticarum rerum exordiis et incrementis_ (composed about 840). "The tradition is that St. Gregory, just as he regulated the order of the masses and of consecrations [_i.e._, the Sacramentary and the Pontifical Rituale] so also had the greatest part in the arrangement of the liturgical chants, following the order which is observed to this day as the most fitting: as is commemorated at the head of the Antiphoner." (_Op. cit. c._ xxi., _Patr. Lat._, cxiv., 948.) [Illustration: St. Gregory, from MS. of Coronation Services] This refers, strictly speaking, to the Antiphonale Missarum. But the following extract treats directly of the chants of the office contained in the _Liber Responsorialis_, or corresponding volume for the hour services. "As for the chants for use at the different hours, whether of the day or of the night, it is believed that it was St. Gregory who assigned to them their complete arrangement, just as he had already done, as we have said, for the Sacramentary." (_c._ xxv., 958.) These two passages establish the fact that there was a tradition in the middle of the ninth century that St. Gregory set in order the ecclesiastical music. It seems also that there was an inscription at the beginning of the Antiphoner stating as a fact that he had done this. The following extract helps us to identify what this inscription was. V.--Agobard of Lyons (779-840). _Liber de Correctione Antiphonarii_, _c._ xv., _Patr. Lat._ civ., 336. "But because the inscription serving for title to the book in question [_i.e._, the Antiphoner] puts in the forefront the name of 'Gregorius Præsul,' thereupon some people imagine that the work was composed by the Blessed Gregory, Pope of Rome and illustrious doctor." He is here defending the chant of Lyons against the ultramontane efforts of Amalarius to introduce the Roman ways. He goes on to try to prove that the Antiphoner defended by Amalarius cannot be St. Gregory's, because he had forbidden the use of words not taken directly from Scripture. VI.--Amalarius of Metz (815-835) is undoubtedly the person who played the foremost part in the fusion of the Gallican element with the rest of the Gregorian or Gelasian Liturgy, from which combination has come in substance the Roman Liturgy in use to-day. He had travelled much, and had been at Rome. He is a weighty authority in the present question. The following extracts are taken from a supplementary chapter of his _De Divinis Officiis_, published by Mabillon, in his _Vetera Analecta_ (_Paris_, 1723). He is speaking of the Pope Gregory who is the author of the Dialogues, and who sent St. Augustine into England.