The Excellence of the Octave
I've been meaning to post on this subject for some time. The commemoration of the Octave of Sts. Peter and Paul, in 2006, inspired me to write. I thought seriously about it after the Octave of St. Benedict and got closer during the Octave of the Nativity of the BVM. As today is the Octave of Sts. Peter and Paul, 2007, the topic again seems appropriate:
One of the elements of Western Rite worship I most appreciate is the existence of the Octave, the deliberate choice to extend the celebration of a given feast for the following seven days. Fundamentally, the Octave honors the saint or holy day by allowing it to impact the Office or Mass — to one degree or another — long after the clock says the observation has expired. The greatest feasts have a privileged octave, meaning the feast is so important its remembrance displaces the actual commemoration of any other feast that happens to coincide with it. Others interact differently with feasts that occur at any time during the intervening eight days. The fundamental principle, though, is that some events in the life of grace are so significant they should be remembered for more than one day. The kalendar offers a hint of this development, keying certain seasons from the great feasts, e.g., the 12 days of Christmas, the Sundays after Epiphany, Paschaltide, and the long season of Pentecost or Trinity (depending on one's relative position to the English Channel). 
In one sense, the Octave allows the Church's most preeminent saints and festivals to tower over feria days. They have ascended closer to God and from that ethereal perch cast their shadows over the following seven days.
In another sense, this is a triumph of God over the human fiction of time. God, the eternal I AM, is the One (and only) Being to stand "outside time, for time is only a form of limited being...For God, there is neither past nor future; there is only the present."  As Mother Gabriel said, "The Joy of Christ is found only in the Present, in the Eternal Present of God." We continue to offer our devotions in anticipation of the heavenly life, in which we will be occupied with nothing else.
This liturgical observation also serves a practical, pastoral function: it engraves into our consciousness the memories of our most outstanding fathers and mothers in the faith. My grandmother — free of every touch of senility until her death, Deo gratias — repeated things ad infintum, almost inevitably centered on family news or memories; occasionally, these would center around family friends I had not seen since being carried out of the maternity ward. So the kalendar points out the exploits of saints whose names we too often do not know (the much-forgotten Sts. Gervase and Protase [protomartyrs of Milan] or St. Saturninus, for instance). When the kalendar adds an Octave, the Church underscores the importance of remembering their martyria, the testimony of their lives. It is a form of spiritual rote-drill. It is the kalendar's way of telling us, "You can say that again."
This is a more pronounced feature of Western Orthodoxy than its Byzantine complement. There, great feasts have dates of leavetaking (apodosis); however, only four "third class feasts" — saints' days in Western parlance — are in this category, and their apodosis is always the following day. It's literally here today and gone tomorrow. In the West, Sts. Peter and Paul, Benedict , John the Baptist, Stephen the Protomartyr, John the Apostle and Evangelist, the Holy Innocents, Joseph, Laurence, and — as a catchall — "All Saints" receive an Octave.
In a transitory world of planned obsolescence, the Octave grows ever more important. God reminds us our "heart is waxed gross, and their ears are dull of hearing, and their eyes they have closed" (St. Matt. 13:15; see also Acts 28:27 and Hebrews 5:11). We often need more than one day, more than one service, to appreciate the splendor of heavenly virtues and the benevolence of their Author.
May our observation of these sacred feasts, and the intercessions of those they honor, ever cause those virtues to take root in us and flower into the bloom of everlasting life. Amen.
1. The penitential seasons likewise anticipate most of these feasts.
2. Fr. Michael Pomazansky, Orthodox Dogmatic Theology: A Concise Exposition.
3. On his solemnity, July 11th.