Understanding the calendar VIB - The liturgical seasons

In the last post we started looking at the cycle of 'movable feasts' that depend on the date of Easter.

Today a look a look at the key seasons and feasts of the year that are dependent on the Easter cycle.

Easter as the focus of the liturgical year

We are used to thinking of Advent as the start of the liturgical year, but in reality the liturgical year cycle originally centred on Easter, which was the first of all the feasts celebrated by the Church.

In fact Advent only became firmly established as the start of the year in the thirteenth century - indeed in the form given to it by St Gregory the Great in Rome in the late sixth century, Advent had a rather eschatological character, as indeed did the season of Epiphanytide as it developed over the seventh and eighth centuries.

Easter

The calculation of the date of Easter each year has been a source of controversy from the earliest years of the Church, with competing dates still celebrated by Orthodox and Catholics.

Even in the modern Western calendar, though, Easter remains the anchor for most of the liturgical year, with the date of many other feasts and special days, including Ash Wednesday, Ascension, Pentecost, The Most Trinity, Corpus Christi, and the Lent and Pentecost Ember Days, dependent on it.

You can read about the way it is calculated here.

For practical purposes, though, it is worth knowing that Easter can never occur before March 22 or later than April 25.

And for a list of the actual dates, consult the 'table of movable feasts' in the front of your Diurnal.

Counting backwards from Easter (1) - Septuagesima 

For Ordo purposes, it is easiest to think of the Sunday cycle as starting with the lead up seasons to Easter rather than Advent.

The traditional calendar has two pre-Easter seasons.

The first, Septuagesimatide, consists of the three weeks before Lent.

It's Sundays - Septaugesima (the ninth before Easter), Sexagesima (eighth before Easter) and Quinquagesima (seventh before Easter) can be traced back to the sixth century.

It was abolished in the 1970 calendar, but was retained in the 1962 calendar to provide a clear end point to the festive season, and soften the transition to Lent.

In the Office it is marked in several key ways:

• the Alleluia not used, with an alternative formula used in the opening prayers of the hours;
• the Scriptural reading cycle at Matins starts at the beginning of the Bible, with Genesis; 
• the collect of the Sunday is used each day at Matins and Lauds and Terce to Vespers, unless displaced by a feast; and 
• there are Magnificat antiphons at Vespers for each day of the week.

The rest of the Office though, remains as for 'throughout the year' during this time, with the ordinary days of the week being Class IV, and the Sundays Class II.

Counting backwards from Easter (2) - Lent

Like Septuagesima Sunday, the start of Lent - Ash Wednesday, a Class I 'day' - is also calculated by counting back the number of days/weeks from Easter.

In the Office, Lent has several phases:

• the days after Ash Wednesday but before the first Sunday of Lent, which are Class III days each with their own canticle antiphons and collects (one for Matins, Lauds, and Terce to None; another for Vespers), but otherwise continues to use the 'throughout the year' texts';
• from the First Sunday of Lent up to 'First' Passion Sunday, where each Sunday is Class I, and the 'Ordinary' of Lent provides the antiphons, hymns and other texts for the hours during the week';
• the two weeks of Passiontide (up to Palm Sunday) which has its own 'Ordinary' texts;
• Monday to Wednesday of Holy Week, which are Class I days with their own antiphons and special texts.  No other feasts can be celebrated during Holy Week; and
• the Sacred Triduum, where a special form of the Roman Office us used for Maundy Thursday to Holy Saturday.

During Lent, Class III feasts that occur on weekdays are reduced to commemorations.

The first week of Lent also includes the first set of 'Ember Days' of the year.

You can read more on the Office during Lent here for the period up to Passiontide, here for Passiontide, and here for Holy Week.

Counting forward from Easter (1) - the Easter Octave to the Octave of Pentecost

The feast of Easter itself is celebrated for seven days, by virtue of its Octave, all of the days of which are considered Class I of Our Lord, and so preclude the celebration of any other feasts.

This means that any first class feasts that occur in this period are transferred to the next available date.

In the modern calendar, the Scriptural number symbolism of Christ's ascension on the fortieth day after Easter (always a Thursday) has subverted in many places by shifting the feast to the Sunday.

In the 1962 calendar though, the Office is governed by the 'ordinary of Eastertide' up to the fortieth day after Easter, and then the ordinary of 'Ascensiontide' for the days up to the fiftith day after Easter, the Feast of Pentecost.

Like Easter, Pentecost also has a Class I Octave when no other feasts can be celebrated.

Counting forward from Easter (2) - Sundays and feasts after the Octave of Pentecost

The first Sunday after the Octave of Pentecost, the Feast of the Most Holy Trinity, marks the start of a new cycle of feasts and Sundays tied to the date of Easter.

Apart from Trinity Sunday, these include Corpus Christi (the Thursday after Trinity Sunday) and the Most Sacred Heart of Jesus (Friday after the Second Sunday after Pentecost).

The Sundays after the Octave of Pentecost are Class II, and are numbered for their distance from that feast, and mark the start of a new cycle of readings at Matins.

For the first weeks after Pentecost (ie up to August), those readings centre on the books of Kings.

From August, though, the monthly reading cycle cuts in and means that the I Vespers Magnificat canticle, the First and Second Nocturn readings for Matins, and the responsories for Matins are determined by the week of the calendar month.

The collect of the week though, as well as the Third Nocturn and Gospel readings for Matins, collects for the week and Sunday canticle antiphons are determined by the number of the Sunday after the Octave of Pentecost.

This means you need to look in two different parts of your 'of the time' section of the Diurnal to find the texts you need each week.

The last Sundays after Pentecost, and Epiphanytide

The final twist to the annual cycle that you need to be aware of is the variable number of Sundays after Pentecost (and Epiphany).

There are twenty-four sets of texts for the Sundays after Pentecost, and six for the Sundays after Epiphany.

But if you consult the table of movable feasts in the Diurnal, you will find that, depending on the date of Easter, there can actually be anything between twenty three and twenty eight Sundays after the Octave of Pentecost.

This happens because Septuagesima can cut short the cycle of six Sundays after Epiphany, while the start of Advent (determined by the date of the Sunday nearest to November 30) can push the start of Advent back as far as November 27 or forward as far as December 3.

The pragmatic solution is to use the Sunday readings, canticle antiphons and collects not used earlier in the year during Epiphanytide to fill in the gap if necessary.

The formula for which Epiphanytide Sunday's texts are used after Pentecost depends on the number of Sundays in that particular year:

• if there are 25 Sundays after Pentecost, the 24th uses the texts for the 6th Sunday after Epiphany;
• if there are 26, the 24th is the 5th after Epiphany, the 25th is the 6th;
• if there are 27,  the 24th is 4th after Epiphany, and so forth; and 
• if there are 28, the 24th is 3rd after Epiphany.

The texts for the 'twenty-fourth' Sunday are always used on the last last Sunday of the liturgical year, no matter what number that Sunday is in any particular year.

In summary....

The table below summarises the level of days (feasts aside) for the key liturgical seasons of the year.

Season	Start/date  determined by	Sundays	Weekdays
Septuagesimatide	Easter	Class II	Class IV
Lent and Passiontide	Easter	Class I	Class III (Class III feasts commemorations only; if a Class I&II feast displaces, commemoration of the Lent day at Lauds and Vespers)
Holy Week and Easter Octave	Easter	Class I	Class I
Eastertide and Ascensiontide	Easter	Class II	Class IV (Vigil of the Ascension, Class II, Ascension Class I)
Octave of Pentecost	Easter	Class I	Class I
Weeks after the Octave of Pentecost	Easter	Class II	Class IV
Advent	Sunday nearest to 30 November	Class I	Class III to 16 December (if Advent day displaced by a Class I, II or III feast, commemoration at Lauds and Vespers); Class I 17-23 November
Christmastide	Fixed date feasts and ferias, December 24-Jan 5	Class II	Vigil and Octave Day Class I; Class II Octave; otherwise Class IV
Epiphanytide	Feast of the Epiphany (Jan 6) and Sundays after; Feast of the Purification (Feb 2); note that end date determined by Easter (Septuagesima Sunday).	Class II	Class IV

And with this we have pretty much covered the calendar!

I plan on one more post, just to bring all of this material together in the sample Ordo have been constructing as we've gone along for August 2018. 

So if you have any questions on any of the material covered in this series, or on things that haven't been answered in it, please do speak up now and I'll try and include the answers in the next (and last) post in this series.