From the Glossary of the Catechism of the Catholic Church:*
PENTECOST: The “fiftieth” day at the end of the seven weeks following Passover (Easter in the Christian dispensation). At the first Pentecost after the Resurrection and Ascension of Jesus, the Holy Spirit was manifested, given and communicated as a divine person to the Church, fulfilling the paschal mystery of Christ according to His promise (CCC paragraphs 726, 731; cf. 1287). Annually the Church celebrates the memory of the Pentecost event as the beginning of the new “age of the Church,” when Christ lives and acts in and with His Church (para. 1076).
Awhile back we started looking at the similarities, and the differences, between the new Liturgical Calendar - which was promulgated in 1969 according Paul VI’s Motu proprio MYSTERII PASCHALIS - and the Liturgical Calendar which had been in use prior to MYSTERII PASCHALIS, the so called “1962 Calendar” which is followed by the Extraordinary Form (the EF, or the “Traditional Latin Mass”). This new calendar was part of the overall revision of the Mass with the promulgation of the 1969 Edition of the Roman Missal – the Novus ordo missae (also known as the OF or “Ordinary Form”)**. I promised, back then, to point out some of the differences in the calendars as we come across them in our journey through the Liturgical Year. We find ourselves at another difference.
Let us jog our memories. In the 1962 Calendar, there were only two main parts, or “Cycles”, to the Liturgical Year: The Christmas Cycle and the Easter Cycle. In the 1969 Calendar, things are broken up a bit differently: There’s Advent, Christmas Time (Christmas Vigil up to the Sunday after Epiphany or after January 6th), the first Ordinary Time, Lent/Triduum/Easter (ending on Pentecost Sunday), and the second ordinary Time.
In the 1962 Calendar, the Christmas Cycle had a season after Epiphany (January 6th) known, cleverly enough, as The Season after Epiphany, and it had up to six Sundays depending on the location of Ash Wednesday. This Season After Epiphany (and, the entire Christmas Cycle) ended the Saturday before Septuagesima Sunday, thus allowing one to sort of slide out of Christmas without abrupt jolts. Likewise, Septuagesima Sunday began the second half of the Liturgical year, the Easter Cycle, as the first of the three pre-Lenten Sundays whose purpose was to help us get ready for the period of Fast and Abstinence known as Lent. My simple-minder way of viewing this was that they allowed a sort of winding down of Christmas, and a gearing up for Lent. These transition periods were eliminated in the 1969 Calendar; right after Epiphany (which may or may not fall on Epiphany, January 6th) we are thrust into the first of the two periods of “Ordinary Time”. This first Ordinary Time ends abruptly on Ash Wednesday.
A similar thing happens with Pentecost. In the 1962 Calendar, and in my Baronius Press 1962 Daily Missal, Pentecost Sunday is also referred to as Whitsunday, referring to the white garments of those baptised during the vigil. Whitsun was, in the 1962 Calendar, a First Class Feast with an Octave week, meaning that there was a unique liturgy for each day of the Octave. Now, the kind and number of feasts and Octaves in the liturgical year have gone up and down through the centuries; suffice it to say that by the 1950’s things were pretty complicated and confusing, and Pope Pius XII simplified things greatly with his General Roman Calendar of 1954, where (among other things) he reduced the number of Octaves from some fifteen or so to three: Christmas, Easter and Pentecost. These three Octaves were carried forward by Pope Paul VI in his General Roman Calendar of 1960, which in turn came from his motu proprio Rubricarum instructum. As it is the 1960 General Roman Calendar that forms the 1962 Missal which is used by Summorum pontificum, we have, in our 1962 Missal Whitsunday, a.k.a. Pentecost, as well as the Octave week of Pentecost.
Thusly, in the 1962 Calendar (and Missal) we have Pentecost, or Whitsunday, followed by the Octave (there are Ember Days during this Octave; one day, but not today, we will discuss Ember Days). The Sunday after Pentecost is Trinity Sunday; this Sunday begins the third part of the Easter Cycle: the Season After Pentecost, which runs up to the First Sunday of Advent.
In the 1969 Calendar (and Missal), Easter Season ends with Pentecost, the Octave of Pentecost is suppressed. Badda bing, badda boom. Thus, there are only two Octaves in the 1969 calendar: Christmas and Easter. The second Ordinary Time begins the Monday after Pentecost, although the Sunday after Pentecost remains Trinity Sunday. Ordinary Time II, of course, runs up until the First Sunday of Advent, when we begin the new liturgical year.
There it is.
* A short post on the development of the current Catechism is here.
** From an older post I offer up this clarification on names for the Rites: “One of the first things one comes up against regarding the Extraordinary Form is the problem of what to call it. It goes by many names, although in this blog I tend to use EF (“Extraordinary Form”) for the Vetus ordo – Old order of the Mass, and OF (Ordinary Form) for the Novus ordo – New order. I do this because that’s how Summorum Pontificum refers to them. Simply calling it "the Latin Mass" is, though widely practiced, not truly accurate, as much of the OF is actually supposed to be said in Latin (and in some parishes in other Dioceses, this is done.)”