Misconception:  Sundays in Lent are part of the Lenten Season and Lent is forty days long

Sundays are neither considered part of the Lenten season nor is Lent forty days in length.  To explain this requires a little history of Lent. 

In the first stage we see that as far back as the year 384 that Lent comprised six weeks and was officially called Quadragesima — literally 40 days.  Quadragesima consisted of the forty consecutive days immediately before the start of the Triduum¹.  This put Lent beginning on the First Sunday of Lent and lasting through Holy Thursday.  Holy Thursday was not part of the Triduum and the Triduum was not part of Lent.  We know all of this to be true because of the writings of St. Leo².  Even though the preceding forty days were all days of Lent, not all of them were fast days so much as they were days of spiritual combat.  Sundays have never been considered days of fast and we can see in the Early Church.   An Apostolic Constitution³ tells us that a man who fasts on the Sabbath is guilty of sin.

The second stage of Lent happens around the time of the fifth century and lasts until Pope Paul VI’s reform of Holy Week in 1969.  In the fifth century we see the development of the Triduum into Holy Thursday - Easter Sunday.  In doing this the character of the forty days was changed and, in an effort to maintain the forty fast days, Lent was reformed to begin on Ash Wednesday, which had previously been not part of Lent but rather a day of preparation, and lasted through Holy Saturday, essentially overlappting with the Triduum.  We can look to the Gelasian Sacramentary of this time as it was the first official text to refer to Lent as beginning on Ash Wednesday.  It is important to note that at this time in History the forty days of fast overlap with the Lenten season, but this has not always been the case and isn’t the case currently.

The third stage of the reform happened by Pope Paul VI in the year 1969.  At this time the season of the Sacred Triddum was restored.  Doing this shortened the Lenten season from 40 days to 38 days, if you count all of Holy Thursday.  The reform of Paul VI stated that the Triduum would begin with the Mass of the Lord’s Supper on Holy Thursday and Last through Evening Prayer on Easter Sunday.  It was also at this time that Pope Paul VI removed the obligatory lenten fast from all days except for Good Friday and Ash Wednesday.  Here we have the nature of the fast removed from the Lenten season.  This revision returns us back to the original calculation and meaning of the Triduum and Lent.  The norms of the Triduum note that on Good Friday and (if possible) and Holy Saturday the Easter fast is to be observed⁴.  So how to we get 40 possible fast days?  You add the 38 days of Lent and Good Friday and Holy Saturday and you end up with 40 possible fast days, though there is no longer an obligation to fast on any those days except for Ash Wednesday and Good Friday.

In Conclusion, Lent is not forty days long but rather 38.  Sundays are not and never have been calcuated as part of Lent. Even the current regulation notes that Lent runs from Ash Wednesday - Holy Thursday, exclusive⁵ (meaning some days in between are not part of Lent, namely the Sundays.)  We also see that from the history that the penitential season of Lent and the 40 days of fast are two separate entities that have not always been one in the same.  This is evident from our current practice where the possible 40 days of fast include the 38 days of Lent and two days of the Triduum.

1. It is important to note also that in the General Norms for the Liturgical Year that the Sundays of Lent and Advent are clearly noted as "Sundays of Lent and Advent" respectively whereas Sunday during Ordinary Time are referred to "Sundays in Ordinary Time."  This is even denoted in the Sacramentary which clearly say "Second Sunday of Lent" and "Second Sunday in Ordinary Time" noting that Sundays of Lent are not in Lent.

2.  See St. Leo the Great’s Sermon #39

3.  250-300 AD Apostolic Constitutions Do you therefore fast, and ask your petitions of God. We enjoin you to fast every fourth day of the week, and every day of the preparation, and the surplusage of your fast bestow upon the needy; every Sabbath-day excepting one, and every Lord’s day, hold your solemn assemblies, and rejoice: for he will be guilty of sin who fasts on the Lord’s day, being the day of the resurrection, or during the time of Pentecost, or, in general, who is sad on a festival day to the Lord For on them we ought to rejoice, and not to mourn. (Constitutions of the Holy Apostles, book 5)

For More information, see Abbot Patrick Regan, O.S.B’s article "The Three Days and the Forty Days" in Worship #54 (1980).  Most of the Information for this article was taken from Abbot Patrick’s article.