Octave (liturgy)

In Christian liturgy, the eighth day after a feast
"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 liturgical calendar of the Lutheran Churches may have octaves for the following feasts: "The Nativity of Our Lord, The Epiphany of Our Lord, The Resurrection of Our Lord, All Saints, Ascension Day, Pentecost and Trinity Sunday."

Churches within the Anglican Communion traditionally observed octaves associated with the feasts of Christmas, Corpus Christi, Epiphany, Michaelmas, Easter, and All Saints' Day. Many provinces have followed the Catholic Church and altered the practice of observing octaves. In the Church of England, the only octave that remains in some form is that of Easter: no other feasts may be celebrated in the six days following Easter Sunday, and only a Dedication Festival or Patronal Festival may be celebrated on the Second Sunday of Easter.

Among the Eastern Orthodox and Byzantine Rite Eastern Catholic Churches, what in the West would be called an Octave is referred to as an Afterfeast. The celebration of the Great Feasts of the church year are extended for a number days, depending upon the particular Feast. Each day of an Afterfeast will have particular hymns assigned to it, continuing the theme of the Feast being celebrated. Most of these Great Feasts (except Feasts within the moveable Paschal Cycle) also have a day or more of preparation called a Forefeast. Forefeasts and Afterfeasts will affect the structure of the services during the Canonical Hours. The last day of an Afterfeast is called the Apodosis (lit. "giving back") of the Feast. On the Apodosis, most of the hymns that were chanted on the first day of the Feast are repeated. On the Apodoses of Feasts of the Theotokos, the Epistle and Gospel of the Feast are repeated again at the Divine Liturgy.

The term "octave" is applied to some church observances that are not strictly liturgical. For example, many churches observe an annual "Octave of Prayer for Christian Unity", which runs from 18 January to 25 January. The octave was established in 1895 by Pope Leo XIII for the period between Ascension and Pentecost. In 1909, Pope Pius X approved the transfer of this octave to the period between the former feast of the Chair of St. Peter (then on January 18) and the feast of the Conversion of St. Paul (January 25). In 1968, the World Council of Churches and the Vatican's Pontifical Council for Promoting Christian Unity agreed to jointly publish prayer materials for the occasion under the title "Week of Prayer for Christian Unity", but it is still often referred to as an octave, especially within the Roman Catholic, Lutheran and Anglo Catholic traditions. The Week of Prayer is observed at various times around the world, especially in the Southern Hemisphere where it is commonly observed from Ascension to Pentecost. Each year, Luxembourg holds what is called the octave celebration from the 3rd to the 5th Sunday after Easter, making it 15 instead of 8 days, in honour of Our Lady of Luxembourg, patroness of the city.