The historic collection of Gregorian music divides itself into two large groups--(1) the music of the Mass, together with that of the baptismal, burial, and other occasional services, corresponding with the modern Missal, and (2) the music of the daily Hours of Divine Service, corresponding with the modern Breviary. There are about 630 compositions in the first large group, in which only scriptural words appear, classified as follows: about 150 Introits (_Antiphonæ ad introitum_), about 150 Communions (_Antiphonæ ad communionem_), 110 Graduals, 100 Alleluias, 23 Tracts, and 102 Offertories. In the music of the second large division (the Hours of Divine Service) there is much less variety than in the music of the Mass. As this group of services did not have the same official position as the Mass, less restraint was exercised in regard to modifications. In this collection are to be found some 2,000 antiphons and about 800 Greater Responds, besides many Lesser Responds, Invitatories, and Versicles. It is now quite generally believed that there were no essential differences between Ambrosian and Gregorian music. If any differences existed, they were in such compositions as the Ambrosian hymn, which was written for the use of the congregation and was more measured and stately in its swing than its Gregorian counterpart, which was sung by the trained choirs and therefore capable of much more rhythmic freedom and melodic embellishment. The Roman singing school (_Schola Cantorum_) played a large and important part both in the labor of codifying the great collection since known as Gregorian music, and in spreading the Gregorian chant among the faithful in other lands. This latter task was greatly facilitated by the establishment of numerous singing schools, modelled after the Roman school, in England, France, and Germany, under the auspices of monastic orders or powerful prelates. Among the most famous of these schools were the one at Metz, founded by Bishop Chrodegang, which maintained great prestige up to the twelfth century; the one at Oxford, founded by Alfred the Great; the monastic school of Fulda, which held the foremost place in Germany; and the one at St. Gall, Switzerland, whose fame and achievements eclipsed all the others and which was celebrated far and near for the elaborateness and excellence of its musical service and for the devotion and enthusiasm of its monks in the advancement of ecclesiastical music during the eighth, the ninth, and especially the tenth century. England became acquainted with Gregorian chant during the lifetime of Gregory the Great, when St. Augustine (not to be confused with the Latin father) was commissioned in 597 as an apostle to carry Christianity to the island across the channel. In France and Germany (Franconia and Allemania) Pepin,[4] and especially Charlemagne, gave energetic and active support to the movement to bring about uniformity with Rome, and by the beginning of