Article III. On the Duty of Reciting the Canonical Hours Specifically

The canonical hours are the complex, chiefly of psalms, readings, and chants, by which ecclesiastical persons, in the name of the Church, daily offer liturgical worship to God. They are distinguished as seven, namely Matins with Lauds, Prime, Terce, Sext, None, Vespers, and Compline, in conformity with these words of Ps. CXVIII, 164: "Seven times in the day have I spoken praise to Thee." They are called "canonical hours" because from their primitive institution they were, as it were, annexed to determinate hours, namely Matins to midnight, Lauds to the beginning of dawn, Prime to the sixth hour, Terce to the ninth, Sext to midday, None to mid-afternoon, Vespers to the time which precedes sunset, and Compline to the time which follows sunset.

The canonical hours are also called the divine office: office, because it is imposed; divine, because it is destined for the worship of God. It is divided into the nocturnal office, to which Matins with Lauds pertains, and the diurnal office, which the other hours constitute. Finally the canonical hours are called the breviary; according to some, because they contain Sacred Scripture and the writings of the Holy Fathers compendiously; according to others, because they are a certain abbreviation of the longer office which formerly was in use. According to others, under the name of breviary there first came a little book containing the rules for ordering the divine office through the course of the year, into which afterwards the diverse parts of the divine office itself were inserted, such as psalms, readings, etc. And thus it happened that finally the office itself was called the breviary.¹

Moreover can. 135 prescribes the canonical hours in these words: "Clerics constituted in major orders ... are held by the obligation of reciting the canonical hours completely each day according to their proper and approved liturgical books." We shall speak first about the object, then about the subject, then about the obligation of the precept, and finally about the causes excusing from the obligation. Moreover we shall chiefly keep solitary recitation before our eyes; nevertheless at the end, for the sake of completeness, we shall speak in one scholion about recitation with a companion, and in another about choral recitation.

¹ Baümer, loc. cit., Appendix I.