John the Deacon describes his Antiphoner as a "cento" (_Antiphonarium Centonem compilavit_), and speaks of him, as we have seen, as "Antiphonarium centonizans." "Cento" is a Low Latin word meaning patchwork, combination, or compilation. "Antiphonarius cento" would therefore mean an Antiphoner compiled from various sources. And this is the character of the Gregorian Antiphoner of the Mass, even of the nucleus which remains after omitting the parts known to have been added since Gregory's time. Indeed the whole phrase quoted above has a ring of truth about it, and makes the tradition which he reports of a more genuine historical character, for if it had been a mere vague tradition in glorification of St. Gregory, he would have been more likely to have spoken of him as the composer of the Antiphoner, and not as a mere compiler. The oldest part of the book is formed of the Feasts celebrated in honour of events and saints spoken of in Scripture, and of the oldest Roman Saints. The Masses for these are taken from Scripture, especially from the Psalms. For Feasts of non-Roman origin, the text is taken from the Church from which they are introduced; _e.g._, the Feast of St. Agatha from the Sicilian Church, or the Feasts coming from the Greek Church which were translated from the Greek. The want of uniformity in the arrangement of the text is seen by comparing the different classes of chants in _Codex St. Gall_, 329. As a rule, the words of one and the same Mass are all of different origin. The most ancient part of the Masses is the Graduals and Tracts, and all these (which are the most ancient solos of the Mass) in the Gregorian nucleus are taken from Biblical sources. This part of the "cento Antiphonarius" is put together in one system after an established tradition. In the oldest Feasts there are Psalm-graduals, but Introits taken from other books of the Bible. The parts other than the Gradual and Tract were chosen on a different system, a considerable number in fact have words not taken from the Bible at all. The Communions, again, form a class by themselves, and were sometimes chosen with special reference to the Gospel for the day, which is the case with no other class of the texts of the chants.