Advent, the period of preparation for Christmas, is, in the Catholic Church at any rate, divided into two parts: the First Sunday of Advent to 16 December inclusive, and 17 December to the afternoon of Christmas Eve. The tone of these two periods can be illustrated by the Prefaces leading into the Eucharistic Prayer. One of these Prefaces is used up to 16 December, and the other thereafter. 

The Fourth Sunday of Advent always falls after 16 December, and the gospels of the Masses are about Mary, the Mother of God. In the first three Sundays the gospel passages are about either the need to be alert and ready for when the Son of Man comes (First Sunday) or they concentrate on the figure and mission of John the Baptist (Second and Third Sundays).

Because of the focus on Our Lady in the latter part of Advent, there used to be the custom, at least in the alpine countries, of having what we call ‘Votive’ Masses in her honour from 17 to 23 December. These were called ‘Rorate’ Masses from the opening words of the Introit “Rorate, caeli, desuper, et nubes pluant justum.” They were also called “gulden mhis” (“Golden Masses”) because the priest wore gold vestments for them rather than the purple of Advent.

The change of emphasis in the days leading immediately to Christmas is also reflected in the Divine Office. This can be seen in the antiphons attached to the Magnificat, which – since at least the time of the Venerable Bede - has formed part of the Church’s Evening Prayer. These antiphons form the climax of the Church’s Advent longing for the coming of the Saviour. 

The images and often the words of these antiphons (which go back to at least the eighth century) are taken mainly from Isaiah, as we shall see shortly. In some monasteries, the custom is (or was) that on 17 December, the abbot – vested in cope and mitre rather than in the monastic cowl – presided at Vespers and solemnly intoned the first of the these special Magnificat antiphons. (Normally it is the Cantor who intones antiphons.)

The antiphons are known as the ‘O’ Antiphons – for the very simple reason that each of them begins with the word ‘O.’ All of them have the same structure. 

Firstly, there is the name – “Wisdom”, “Adonai” (“Lord”), etc. 

Then comes a description of what he/she/it does. 

The antiphon concludes with a plea “Come…”

I’m not sure when the ‘O’ Antiphons first became part of the Advent Office. What I do know is that someone with the love of word-play one often finds in ancient times discovered that if you work backwards from 23 December, the initials of the Latin names spell out the two words “Ero cras” (“Tomorrow I will be”).

Please look at the individual antiphons and try to reflect upon them in a prayerful spirit, seeing how they gradually build up into a crescendo until Vespers on Christmas Eve when the Magnificat Antiphon is:

“When the sun rises in the heavens you will see the king of kings. He comes forth from the Father like a bridegroom coming in splendour from his wedding chamber.”