The Psalms of Matins for feasts**

Although some have argued otherwise, the special sets of psalms used for feasts - the Commons, and special sets for particular feasts - are in my view, almost certainly a Roman import to the Benedictine Office.

The Roman Office of nine psalms for feasts

St Benedict, after all, insisted that all 150 psalms be said each week, and use of special psalm sets to displace the twelve he set for Matins each day interferes with this principle, as assorted Carolingian commentators noted in the ninth century.

Unlike the Roman Office, the Benedictine, even now, does not use the Sunday psalms for feasts for example.

And it is certainly generally accepted that the two Lauds 'festal psalms' are a Roman import; their adoption into the Benedictine Office was relatively early, but clearly documented as a change.

Moreover the first hard reference we have to the Commons for Matins as far as I am aware actually comes from an eighth century letter from the abbot of Monte Cassino defending a number of romanizations of the Benedictine Office, including maintaining three readings even on summer weekdays (when St Benedict specified only one short reading).  The letter makes clear that no tradition of twelve psalms had been handed down in the Benedictine tradition - instead they divided some of the nine to get to twelve!

Nonetheless, the tradition of special psalms for feasts is well-embedded in the Office now, so I thought it might be interesting to provide a listing of the psalms of the commons and feasts so you can see which are used for most or all feasts; which are identified with a particular type of feasts or saint.

The psalms of the Commons

The 'Commons' for feasts for types of saints/feasts for Matins include an invitatory antiphon, hymn, antiphons, psalms, canticles, versicles, readings and responsories.

All of these elements bar the psalms though, can be displaced for feasts that have come to be more elaborated, with special sets of antiphons and so forth for the feast.  A good example of this is the feast of the Assumption, which retains only the psalms and canticles of the Common.

Table 1 shows the psalms used in the Commons. The bolding indicates psalms unique to that particular Common.

Table 1: Psalms of the Commons

Apostles	BVM/ Female saints	Confessors	One martyr	Several martyrs	Dedication of a Church
		1	1	1
		2	2	2
		4	4
		5	5		5
	8	8	8
		10	10	10	10
		14	14	14
				15
18	18
		20	20
	23	23	23	23	23
					28
				32
33				33
44	44
	45			45	45
46
	47				47
60				60
63			63	63
			64
74
				78
					83
	84
	86				86
					87
					90
			91
95	95	95			95
96	96	96
97	97	97
98	98				98
100

All up there are 34 psalms usd in the Commons, with the most commonly used being Psalm 23, featured in all of the sets except for Apostles

It shows that the Commons of apostles and for the Dedication of a Church have the most unique psalms (three in each case), while the psalms for confessors are all shared with other sets of Commons.

Psalms for other feasts

Table 2 shows the psalms used for other major feasts of the year.  The highlighting indicates the most frequently used psalms. Six of the psalms of the Commons (64, 74, 78, 90, 91 and 100) are not used for any of these feasts.

Nativity	Epiphany	Easter	Ascension	Pentecost	Trinity	All Saints
		1		1		1
2
						4
						5
		8	8	8	8	8
						14
			10	18	18
		15
18			18
			20
23		23	23	23	23	23
				26
		27
	28			28	28
		29	29
						30
						31
				32	32
						33
44
	45		45	45	45
	46		46	46	46
47	47			47	47
						60
		63
	65	65
71	71				71
		75
						83
84
	85
	86
		87
88
95	95		95	95	95
96	96		96		96	96
97	97			97	97
	98		98
			102
		107

Corpus Christi	Sacred heart	Transfiguration	Holy Cross	Christ the king
1			1
			2	2
4			4
			5
		8	8	8
			10
15
		18
19
			20
22			22
				23
				28
	32
	33
	35
	40
41
42
		44		44
		45
	46	46		46
		47		47
	60
				71
		75
80
83		83
84	84
	85
86		86
		88
	93
			95	95
	96	96	96	96
	97		97	97
98			98	98
		103
	107