Q. How did the Octaves in the Church liturgy develop? Are Christmas and Easter the only two octaves the Church calendar recognizes?
A. Here’s a reply from Father Reginald Martin:
“Octave” comes from the Latin word for “eight,” and in our liturgical life can refer to an eighth-day period or all of the eight days following a liturgical feast. The Church inherited liturgical octaves from our Old Testament ancestors, who enjoyed eight-day celebrations of the Feast of Tabernacles and the dedication of the Temple.
However, octaves go back to the beginning of time, when God rested after the work of creation. This was, to be sure, the “seventh” day, but if we count on our fingers (and include both the first and seventh days in our calculation) we discover the final day is really an “eighth” day. Octave days bring to an end a weeklong celebration of a special event.
The emperor Constantine appears to have introduced an octave of Easter, which served as a retreat for those baptized at the Easter Vigil. By the eighth century the privilege was extended to Christmas, Epiphany and Pentecost. By the Middle Ages, the Church celebrated numerous octaves, throughout which the prayers and readings at Mass did not change. Ponitffs since Pope Pius V (d. 1572) have simplified liturgical rules, and since 1969 we observe octaves only of Easter and Christmas.