A nocturn, a round of Psalms, was said on Saturday night by the vigilants preparing for the Sunday services. Before the eighth century two other short nocturns were added. This addition, which was copied from the monastic practice, built up the three nocturn form of office and became the model and form of the office for saints. "There is good reason for believing that originally the Divine Office formed part of the Mass. The _synaxis_, for which the early Christians assembled by night, consisted of the 'breaking of bread,' preceded by the singing of psalms and hymns, litanies and collects, readings, homilies, invocations and canticles. This was the whole official liturgical prayer, apart, of course, from private prayer" (Dom Cabrol, _Day Hours of the Church_, Introduction, p. xvi). One of the chief objects of Pope Pius X. in his reform was the restoration of the liturgical importance of the Sunday office, the office of the Lord's Day, and, therefore, in its own right, superior to the saints' feasts by which it had been displaced from its special office, psalms and lessons. And this could only be effected by a change in the rules of occurrence, and in Title IV. (_De Festorum occurentia_, etc., section 2) we find the new rule for restoring Sunday offices to their proper liturgical rights. In Title IV., sect, 1 (see Breviary, Additiones and Variationes) there is no change in the old rubric. The eight Sundays of the first class exclude every other feast. And the Sundays of the second class only give place to a double of the first class and then are commemorated at Lauds, Vespers and Mass, and have the ninth lesson in Matins. But section 2 (_Dominicis minoribus_)... goes to the root of the matter of the new change in the rules for Sunday's liturgical office. The ordinary Sundays ranked as semi-doubles and hence their Mass and Office was superseded by the Mass and Office of some occurring feast. The length of the Sunday office, in the breviaries until lately in use, made many hearts rejoice over the occurring feast. But the almost total omission of the ancient and beautiful Sunday Masses was a misfortune and, in a sense, an unbecoming practice, which broke away from ancient liturgical rule and tradition. The abbreviation of the Sunday office in the new breviaries and the rule laid down in Title IV., sect. 2, restore Sunday's office and Sunday's Mass to their old and proper dignity. The general rule laid down is that on Sundays throughout the year the proper office of the Sunday shall always be said. The exceptions are (1) Feasts of our Lord and their octaves, (2) Doubles of the first class, (3) Doubles of the second class. On these days the office will be the office of the feast, with commemoration in Lauds, Vespers and Mass. Henceforth Sundays are divided into: (1) Sundays of the first class, which exclude all feasts; (2) Sundays of the second class, which exclude all feasts save doubles of the first class;