And really this is about becoming familiar with the sections of the diurnal dealing with the Propers of the saints, page numbers in square brackets [ ], the Common of Saints, page numbers in normal brackets ( ), and the special supplement for particular places, **.
A lot of this may make more sense once we've taken a look at the specific parts of the Office and each of the hours, but it is still worth getting familiar with now, so I'll use a few examples relating to particular feasts to help you familiarise yourself with it.
Celebrating the saints - rubrics
The propers provided in the Diurnal basically displace the normal 'day of the week' ordering of the Office to a greater or lesser degree, depending on the level of the feast and the texts available for a particular saint.
In working out how the Office is going to be affected on a particular saints day, the first thing to do is look at the rubrics set out in calendar date order in the Proper of the Saints section. So a saint who rates a memorial, such as St George, pg  has the least impact on the Office - in general it only affects Lauds by adding an antiphon, verse and prayer after the prayer set for the day. A higher level feast, though, like that of St Mark, p  affects the choice of texts and even psalms (at Lauds and Vespers).
It is also worth checking the supplement from time to time, since general Ordos may miss feasts particular to your country or diocese - in the case of St George, for example, it is a first class feast in England, and the rubrics are set out on page 24**.
So it works like this. Your starting point is the psalter section of the diurnal. So on St Mark's day in 2009, you would start by looking at texts for a Saturday. But in fact the rubrics direct you to the common of Apostles in Eastertide, which tells you:
- at Lauds to use the 'festal' psalms on page 44 of the psalter instead of the Saturday ones, and use the antiphons and other texts of the common instead of the regular text, and the collect from the Proper of the saint, on ;
- at Prime you would use the first antiphon from the common (Sancti tui) instead of the Saturday antiphon (but with the normal Saturday psalms);
- at Terce, Sext and None you use the hymn and psalms as usual for Saturday, but the antiphon, chapter and versicle of the common, and the collect of the saint;
- Vespers uses the antiphons for Eastertide on (20) and the psalms for apostles on (2), plus the other texts set out instead of the regular Saturday ones, but also adds a commemoration of the Sunday (Magnificat antiphon, verse and collect) after the collect of the saint;
- Compline is as per usual!
As the example above illustrates, the texts that displace those of the day can either be 'proper' to that particular saint (as for example for SS Odo, Majolus, Odilo and Hugh, on page , or from the commons provided for particular classes of saint.
The commons are particularly useful - imagine that in your parish or diocese it is the first class feast of a local saint. Your saint isn't mentioned explicitly in the Diurnal though. Provided you know what type of saint he or she is - an apostle, martyr, confessor, virgin or whatever - you can simply to to the relevant common and use those texts in order to say the appropriate Office for the feast. So it is worth flicking through the commons and becoming familiar with the categories of saints!
The other point to note is that the commons include some particular psalms for the feast. At Lauds, first and second class feasts rate the 'festal' psalms, which can be found in the psalter. There are quite a few different selections of psalms for Vespers though (and for Matins in the breviary if you are attempting to say the full Office), set out in the respective commons.
The diurnal charts
If you want to work out what can and can't change according to the feastday, here is where that chart that comes with the Diurnal comes in handy. On one side of it you can see the summary of Terce, Sext and None. The first column on the table lists the parts of the Office that can change - which for these hours are the antiphons, psalms, chapter and versicle, and collect. The next two show the possible variants - Sundays, ferias and feasts. It shows that feasts never displace the psalms of the day at these hours, but can displace the propers of the season.
In the case of Vespers and Lauds, the tables distinguish between feasts that come with their own specific antiphons, and those without. We will come back to these tables in the context of looking at each hour individually!
For the next part of this series, click here.