Catholic Encyclopedia (1913)/Proprium
The Proprium de tempore and the Proprium Sanctorum form in the present liturgy the two principal portions of our Breviary and Missals; the first comprises the parts appointed for the days of the year having special Masses or Offices (introits, prayers, lessons, responses, versicles, antiphons, etc.); the second is devoted to the Offices of the Saints.
The Proprium de tempore begins with the first Sunday of Advent and ends with the last Sunday after Pentecost. It includes, after Advent, the parts assigned for the Christmas season (six Sundays); Septuagesima, three weeks; Lent, six weeks; Paschal time, fifty days; Pentecost, and the twenty-four Sundays after. Most of the Sundays comprising this cycle, and often weekdays, have special Offices which composed the Proprium de tempore.
The Proprium Sanctorum comprises all the saints' days with special Offices, from St. Andrew on 30 November. The Offices of the saints, like those de tempore, are composed of lessons, antiphons, responses, hymns, or other liturgical passages special to these saints' feasts. It is unnecessary to remark that this arrangement is not primitive. Ages passed before the present liturgical cycle was evolved. In the Liturgical Books before the ninth or eighth century, the Sundays after Pentecost form groups, called after some solemn festival, St. John the Baptist, the Apostles, or St. Michael; the season of Septuagesima did not yet exist, at least in its entirety. A century or two later the Christmas season had not been evolved, even the weeks of Advent had practically no special Offices. In the first ages of the Church, except for the feast of Easter, Christmas Day, and Sundays, the liturgical cycle did not exist. The Divine Office and the Liturgy of the Mass were performed with the help of the books of the old and the New Testaments, and consisted in the chanting of psalms or canticles, readings, exhortations, and impromptu prayers. The liturgical cycle, that is, the feasts of the year or of the martyrs exerted hardly any influence on the Liturgy, and in this sense it may be said that in the beginning there was neither a Proprium de tempore nor a Proprium Sanctorum. Probst (op. cit. infra) thinks that it was at Rome, in the fourth century under Pope Damasus, that this liturgical "reform" took place, especially in arranging the liturgical prayers to suit the season and the feasts of the saints. This may be accepted with some reservations, as it is indisputable that even then the cycle had exerted its influence on the liturgy, in certain special circumstances. It seems certain that the origin of the Common of the Saints is the same as that of the Propria, and that it was at first a Proprium; for instance, the Common of the Apostles was originally the Proprium of the Apostles St. Peter and St. Paul; and the Common of a Martyr was originally the Proprium of St. Stephen and St. Lawrence.