Brush up your rubrics - what changes and what doesn't on major feasts

One of the things that can trip people up when saying the office is which parts of the Office do and don't change on feast days.

Levels of days

The first thing you need to know is that in the 1963 calendar used in the Ordo on this blog there are basically four levels of days - Class I (class one), Class II (class two), Class III (class three) and Class IV (class four).

Class IV means an ordinary day, with no feasts on it, so the Office is said as set out in the psalter section of the Diurnal, using any texts appropriate for the day/season/time of year.

Days that are Class III or higher will displace some or all of the normal day of the week/season texts used.  Which texts are affected and used instead depends on the hour of the Office being said, and the level of the feast.

Days vs feasts

A key distinction to be aware of is between 'days' (ferias) and feasts.  This coming Friday and Saturday for example, are Ember Days and are Class II, however only the collect (at the day hours other than Prime and Compline) and NT canticle antiphons change.

By contrast, on a second class feast like that of St Matthew on Wednesday, many more of the texts will change at some of the hours.

Chant tones vs texts

The other thing to note is that if you are listening to a podcast of the Office, or attending it in person in a monastery, it might all sound different even when the texts are actually mostly not changed.

At Prime, for example, the only text that changes on a feast is the antiphon.  However, where it is sung using Gregorian chant (rather than just recto tono, or on one note), a different hymn tune will normally be used to reflect the level of the feast, and the psalm tone used will reflect the antiphon for the feast.

What changes and what doesn't on Class I&II feasts?

The table below summarises whether or not the relevant part of the Office changes on a Class I or II feast.  In general:

• the opening and closing prayers (other than the collect) do not change (but the opening prayers might have a more elaborate chant tone);
• Compline is not affected by feasts (except that the solemn tone for the Marian antiphon might be used);
• at Prime, the only thing that changes is the antiphon for the psalms.

Affected by Class I&II feasts?	Matins	Lauds	Prime	Terce, Sext & None	Vespers	Compline
Opening prayers	No
Hymn	Yes	Yes	No	No	Yes	No
Antiphon(s)	Yes	Yes	Yes	Yes	Yes	Not applicable
Psalms	Yes	Some	No	No	Yes	No
OT canticle(s)	Yes	Yes (optional festal)	na	na	na	na
Chapter	Yes	Yes	No	Yes	Yes	No
Versicle	Yes	Yes	No	Yes	Yes	No
Responsory	Yes	Yes	No	na	Yes	na
Antiphon for NT canticle	na	Yes	na	na	Yes	na
NT canticle	Yes	No	na	na	No	na
Reading(s)	Yes	na	na	na	na	No
Collect	Yes	Yes	No	Yes	Yes	No
Closing prayers other than collect	No

Hope this helps a bit, but do ask if you have any questions, or let me know if I've made a mistake!