What is an octave? (Glad you asked: Q&A on church teaching).

"Octave" has its linguistic roots in the Latin word for eight, octo. Musicians speak of octaves when they refer to the eight-note distance between matching tones, but the church's liturgical calendar has its own use for the word as well. In effect, the octave is a way of making an especially important liturgical celebration last for a complete eight-day cycle, beginning and ending on the same day of the week. Thus, the Octave of Easter begins on Easter Sunday and ends seven days later, on the Second Sunday of Easter.

Throughout the history of Western Christianity, numerous feasts have been raised to the status of an octave, but reforms since the 1950s have seen all liturgical octaves suppressed except for Christmas and Easter. There is also a traditional "great octave," comprising the eight weeks following Easter and concluding on Pentecost Sunday.

Historians disagree on the roots for this church practice. Some point to Jewish celebrations that lasted for eight days, like the Feast of Tabernacles or the Feast of the Dedication of the Temple. When the Roman emperor Constantine legalized Christianity, he donated numerous basilicas (public buildings) to the church, and these were consecrated to their new use as Christian "temples." As these Roman basilicas were consecrated to Christian worship, the similarity to ancient Jewish celebrations of the Temple's dedication may have been strong enough to suggest that the new Christian places of worship also be celebrated for eight days.

Today, by limiting the number of octaves to two, the church demonstrates the primary importance we place upon Christmas and Easter.

Liturgically speaking, the commemoration of Jesus' birth is not just a single celebration. It is actually a series of eight celebrations that begins on Christmas and ends a week later, with the Feast of the Holy Family on January 1. Though most parishes keep their weekly Masses simple to allow working parishioners to get to work, the church actually calls us to celebrate every day in the octave with the same spirit with which we celebrate Christmas Day itself. If the parish owns special Christmas vestments, they should be worn each day. Ideally, Christmas hymns should be sung every day of the octave, and the Gloria should be sung or at least recited.

In today's world with its secular celebrations and feasts, it is easy to forget that the idea of a "holiday" is actually rooted in our Christian notion of a "holy day." The time-honored tradition of the octave indicates the special character of a liturgical celebration, extending it from one holy day into eight.

By JOHN SWITZER, a doctoral candidate in religious education at Boston College, where his research centers on interreligious learning.