It has been already observed that Saturday as well as Sunday had its liturgical observance. In certain Eastern countries it attained to a position almost equal to that of Sunday. For, in the Apostolic Constitutions, it is laid down that the faithful shall attend divine service on this day also, and abstain from servile work,[27] although the rank of Sunday was acknowledged to be higher.[28] The Council of Laodicea forbade indeed, as we have observed above, the abandonment of work on Saturday, but it enjoined the reading of the Gospel as on Sunday (Can. 16). Traces of this pre-eminence of Saturday among the week-days exists at the present time in the Churches of the East.[29] In conclusion, it is to be noticed that, in the Middle Ages, the rest from labour commenced, contrary to our present custom, with the Vespers of Saturday. Pope Alexander III., however, decreed that local custom should retain its prescriptive right, and so it came to pass that the practice of reckoning the feast day from midnight to midnight became general.[30] 3. _The Classification of Festivals_ According to the points of view taken, festivals may be divided into different classes:— 1. According to the object of the festival, into festivals of our Lord and festivals of the saints. The former fall into three divisions: (_a_) movable feasts—Easter, Pentecost, etc.; (_b_) immovable feasts—Christmas, Epiphany, etc.; (_c_) such as are not included in the above cycles and are immovable, _e.g._, the Transfiguration, Invention of the Cross, etc. The saints whose feasts are celebrated are either Old Testament personages—although these do not appear in the Roman Calendar as they do in others, especially those of the Oriental Churches—or Apostles, martyrs, virgins, confessors, angels, and, finally, the Mother of our Lord. 2. With regard to their observance, festivals may be either local or general. 3. According to their character, we may theoretically divide the festivals into commemorative and devotional festivals. Commemorative festivals are those which celebrate a historical event, _e.g._, the birth, and death of Jesus, the death of an Apostle, of a martyr, etc. These, in many cases, are celebrated on the actual day of the event commemorated. As devotional festivals, we may rank those which celebrate some mystery of the Faith, _e.g._, the Holy Trinity, or those which, although they commemorate a particular event, such as the Transfiguration, do not celebrate it on the day on which it actually happened. Since the number of festivals altered much in the course of centuries, and their objects are so various, they are distinguished from one another by differences of rank and a whole series of gradations has arisen.