Octave (liturgical)

"Octave" has two senses in Christian liturgical usage. In the first sense, it is the eighth day after a feast, reckoning inclusively, and so always falls on the same day of the week as the feast itself. The word is derived from Latin octava (eighth), with dies (day) understood. In the second sense, the term is applied to the whole period of these eight days, during which certain major feasts came to be observed.

Octaves, not being successive, are quite distinct from eight-day weeks and simply refer to the return of the same day of a seven-day week in the inclusive counting system used in Latin (just as the ninth day was a return to the same day of a nundinal cycle, the eight-day week of the pre-Christian Roman calendar).

The "eighth day" or octava dies was associated with the weekly Christian celebration of the resurrection of Christ every "eighth day", which became a name for Sunday.

As circumcision was performed on the "eighth day" after birth, the number 8 became associated also with baptism, and baptismal fonts have from an early date often been octagonal.

The practice of octaves was first introduced under Constantine I, when the dedication festivities of the basilicas at Jerusalem and Tyre, Lebanon were observed for eight days. After these one-off occasions, annual liturgical feasts began to be dignified with an octave. The first such feasts were Easter, Pentecost, and, in the East, Epiphany. This occurred in the fourth century and served as a period of time for the newly baptized to take a joyful retreat.

The development of octaves occurred slowly. From the 4th century to the 7th century, Christians observed octaves with a celebration on the eighth day, with little development of the liturgies of the intervening days. Christmas was the next feast to receive an octave. By the 8th century, Rome had developed liturgical octaves not only for Easter, Pentecost, and Christmas, but also for the Epiphany and the feast of the dedication of a church. From the seventh century, saints' feasts also began to have octaves (an eighth-day feast, not eight days of feasts), among the oldest being the feasts of Saints Peter and Paul, Saint Lawrence and Saint Agnes. From the twelfth century, the custom developed of liturgical observance of the days between the first and the eighth day, as well as the eighth day. During the Middle Ages, octaves for various other feasts and saints were celebrated depending upon the diocese or religious order.

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