(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;
(3) The ordinary Sundays, which exclude all but doubles of the first or second class, feasts of our Lord, and their octave days.
The date of Easter is the pivot of Calendar construction. Before Easter come the Sundays of Lent and Quinquagesima, Sexagesima, Septuagesima Sundays. Septuagesima cannot fall earlier than the eighteenth day of January, nor later than the twenty-second day of February. Hence, in some years there are fewer "Sundays after the Epiphany" than in others, owing to the dates of Easter and Septuagesima. The smaller the number of Sundays after Epiphany the greater is the number of Sundays after Pentecost. If the number of Sundays after Pentecost be twenty-five, the twenty-fourth Sunday will have the office of the sixth Sunday after Epiphany. If there be twenty-six Sundays after Pentecost, the twenty-fourth Sunday will have the office of the fifth after Epiphany, and the twenty-fifth will have that of the fifth Sunday; the twenty-sixth will be the sixth Sunday's office. It should be remembered that the Sunday called the twenty-fourth after Pentecost is always celebrated immediately before the first Sunday of Advent, even though it should not be even the twenty-third Sunday after Pentecost.
TITLE V.—FERIAL OFFICE.
Etymology and different signification of the word Feria. The word is derived probably from the Latin feriari (to rest). Among the Romans, the idea of a day of rest and a holy day was intimately united and received the name of feria. But it was amongst the Hebrews that the day set apart for the worship of God received the most distinctive character as day of rest (Heortology, p. 2). Hence the early Christians called the days of the week feriae.
Why did the Church adopt the word feriae? She wished to mark the day of the week and not to name them by their pagan name (e.g., dies lunae) nor by their Jewish names (e.g., prima sabbati), which should be a sort of recognition of the dead and dying synagogue. Hence she adopted the word feria, to denote the Christian rest in the Lord, the Christian peace and the abstinence from all sin, and that each and every day should be consecrated to God. The Christian use of the word is found in Origen (185-254) and was fully established in the time of Tertullian.
In the time of Amalare (circa 830) the ferial office had taken a well-defined form, Matins having twelve psalms and six antiphons. In Lauds of every feria were recited the psalms, Miserere; Deus, Deus meus; Deus misereatur nostri; a canticle drawn from a prophet and varying each day of the week (e.g., Confitebor, Isaias xii., for Monday's Lauds; Ego dixi, Isaias xxxviii., for Tuesday's Lauds, etc., and the two psalms Laudate (148, 150) and the Cantate, psalm 149). In the small hours the Sunday psalms without antiphons were recited. Vespers had daily, fixed psalms. At each hour the Kyrie Eleison and ferial prayers were said on bended knees and the hours terminated—as do the hours of Holy Week still—with Pater Noster and Miserere.
Ferias are divided into three classes, major ferias, privileged ferias and non-privileged. Ash Wednesday and the three last days of Holy Week are the major ferias which are privileged and exclude all feasts (vide Tit. II., sec. 2). Non-privileged feriae are the feriae of Lent and Advent, Quarter Tense or Ember days and Rogation Monday. They take precedence of simple feasts only.
In the ferial office nine psalms are said, and not twelve, as in the old order of the Breviary. The psalms found arranged in the new Breviary for three nocturns are to be said with nine antiphons up to the versicle of third nocturn—the versicle of the first and second being omitted (Tit. I., sec. 7). Hence the psalms are to be said straight through (sine interuptione) omitting in the first two nocturns, the versicle and response, Pater Noster, absolutions and all pertaining to the lessons. This simplifies things and makes the ferial office shorter than the office of feasts.