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.

In the first place there are purely ecclesiastical festivals whose celebration is confined within the four walls of the Church (festa chori), and festivals which have their bearing upon the common life of the people, chiefly on account of the rest from labour which is conjoined with them (festa fori).

The so-called feriæ and the festivals strictly so called are clearly distinguished from one another. According to the practice of the Church, the ordinary days of the year have their place in the liturgy, and share to a certain extent in the festal character of the season, although distinguished from those days on which is commemorated some mystery of our redemption or the memory of a saint. These latter are holy days (festa) in a higher sense.

These holy days again are divided into greater or lesser feasts—in the language of the rubrics, into festa duplicia and simplicia, with an intermediate class, the semi-duplicia. This is more marked in the arrangements of the Breviary than in the Missal. This does not exhaust the differences between festivals, for there are further distinctions in their rank, especially in the case of the festivals of our Lord and of the chief mysteries of our redemption, i.e. duplicia majora, and duplicia primæ and secundæ classis. The festa duplicia primæ classis are usually kept up for eight days—the so-called octave; so too some of the secundæ classis.

The different rank of feasts is not so elaborate among the Greeks and Russians, for they divide their festivals simply into greater, intermediate, and lesser, which are marked in their Calendars by special signs.

The octave which belongs to the chief festivals has its origin in Judaism, for the Jews prolonged for eight days the festivals which commemorated the two chief religious and political events in their history—the Exodus from Egypt or the Passover, and the Dedication of the Temple.[31] With regard to the Passover, there was another reason for prolonging the feast during eight days. Since many Jews, after the Exile, remained scattered throughout various countries, there was a risk, owing to the uncertain character of the Jewish Calendar, that the correct date of the feast might not be known to all. In order to avoid the misfortune of celebrating the feast on a wrong day, the feast was prolonged for eight days, one of which would certainly be the right day. The first, second, seventh, and last days were especially regarded as festivals.[32] Then Pentecost and Christmas were also observed with an octave, and so matters remained for a long period. It was owing to the influence which the Franciscan Order exerted in liturgical affairs that the number of octaves was increased. The Franciscans provided an inordinate number of festivals with octaves in their Breviary, and observed each day of the octave with the rite of a festum duplex. In this way a number of saints’ festivals, in addition to the feasts of our Lord, were provided with octaves. According to the ancient Roman rite, the observance of the octave consisted merely in a simple commemoration of the festival inserted in the office on the eighth day, without taking any notice of the festival on the intervening six days.[33] A single example of this ancient custom still exists in the Breviary in the festum S. Agnetis secundo.