Since the fifth century, the holy duties and the canonical prayers to which the liturgy consecrated the different hours of the day have been known under the name of _offices_, or _canonical hours_ (Fig. 184), and of _breviaries_. In Tertullian we already meet with the words _Tierce_, _Sexte_, and _None_. St. Cyprian, St. Clement of Alexandria, St. Jerome, and many other fathers of the Church, assigned certain hours at which to recite the different offices, in such a manner that before the close of the fourth century psalmody seems to have been already regulated in the principal churches of the East. The practice of the Western churches differed, it is true, from that of the churches of the East; many differences even were to be found in the dioceses of the same country. But, during the earlier centuries, it was everywhere customary to perform the principal offices at night, which was divided into four watches of three hours each: these hours were measured by a water-clock, termed clepsydra. The first watch commenced at sunset (_ad vesperas_), the second at midnight, the third at cockcrow, the fourth at dawn. Towards the fifth century the piety of the early Christians having somewhat abated, it soon became customary not to go to church till the fourth watch, when the whole psalmody, that is to say, the twelve psalms, as there were three psalms in each watch, was got through at one repetition. Hence the name of matins (_matutinæ_). It would seem that the monks themselves, who were more conservative of ancient rites than the secular priests, commenced about this period to chant the _Nocturn_ and the _Laud_ at the morning hours. Rome alone rigorously preserved the distinction between the offices of the day and those of night. [Illustration: Fig. 184.--Ancient Legend of Christmas, with the words of the old French plaint. The engravings represent the Sibyl prophesying the Birth of Christ; Jesus in the Stable at Bethlehem; one of the Magi; and John the Baptist announcing that Christ was born.--Fac-simile from a book of _hours_, printed with illuminations at Paris by Anthoine Vérard, towards the close of the Fifteenth Century.] The _Petites Heures_ were known as _Tierce_, _Sexte_, and _None_; _Prime_, the first of the canonical hours, was not instituted till the twelfth century, but the other three appear to date from the earliest institution of Christianity. St. Cyprian, who lived in the third century, says that prayers were said at _Tierce_ in honour of the descent of the Holy Ghost, at _Sexte_ in memory of the Crucifixion, and at _None_ to commemorate the death of Christ. Half a century earlier Tertullian wrote that, independently of the mystic traditions consecrated by prayer, the Church, in establishing the canonical hours, wished to conform to the secular division of the day.