(1) No (2) See (1)

https://snowflakeclockwork.blogspot.ca/2013/05/holy-trinity.html

Sing it to Lauda Sion.

Not liturgical, today. Use it as a communion anthem, maybe.

@Salieri

While I am in favor of the restoration of (some of) the Pre-Tridentine Sequences, I'm curious what your plan is here. You can't (can you?) use this piece as originally intended. Will it be just a choir "anthem."

But it needs to be a sequence in the current approved liturgical books (OF or EF) to count as an optional sequence qua sequence.

Yes, though at least the DI is in current approved liturgical books. The effective rule is whether the pastor will accept or resist the idea. To my mind, if a family requests it, and it can be done, I don't think a pastor would be *wrong* to permit it, as the relevant legislation is ambiguous - reasonable arguments could be presented on either side of it.

I've seen some worship aids where folks just run Latin texts through Google Translate and then print them... I know Salieri would never do this... but for fun I threw the sequence on there to see how it would translate it and the results are pretty fun.

professing unity
Trinity venerate
In the same respect,
Three persons asserting
personal differences
The essential difference.

These things are relative,
Since they are one substantive,
There are three principles.
Whether it is three or three,
But one substance,
There are three essential.

Simply being able to be simple,
A simple desire to know a simple,
All simple.
Not one but two
Or three persons
Minor efficacy.

The Father, Son, and Holy Spirit,
God is one, but they still
They have certain properties.
One power, one deity,
One light, one light,
This one is different.

Father offspring is equal,
Do not take this personal
Both distinction.
Comparable to the Father and the Son,
From both a spiritual
Proceeds connection.

No human reason
These persons can be arrested,
Neither of these made.
This order is not temporary,
Not in this country, or local
The circumscription.

Nothing in God but God,
There is no other cause
Cause of all causality.
Effective or formal
The cause of God, and the final
But no matter;

Touching talk about persons
Transcends reason,
Exceeds characters.
What it is to birth is, that the process,
I confess I do:
But faith is not in doubt.

Who believes this, not in a hurry,
And by the way, did not decline
Ne'er palace.
Keep the faith, customs forms,
Do not turn to errors
And the Church of God.

We take pride in the faith,
We play in one
Consistent:
Praise is threefold,
And Triune
Eternal glory! Amen.

Here is the Prose for Trinity Sunday Os superbum conticescat from the supplement Offices Notés propres au Diocèse de Lyon, 1937.

My comment has disappeared, (and now appeared below)

There are a number of Sequences for the Trinity,

music here for Profitentes Unitatem, https://societyofstbede.files.wordpress.com/2015/05/profitentesunitatem.pdf

The Melody is from “Les Proses d'Adam de Saint-Victor: Texte et Musique, by E. Misset and Pierre Aubry.” this book is on the internet archive, and has all of the melodies, and commentary in french. N.B. this book has abbreviated Latin text

Metrical English translations can be found for all the Adam of St. Victor Sequences, in 3 vol. here, https://archive.org/search.php?query=DIGBY S. WRANGHAM

The Liturgical year, Gueranger has this sequence (Vol. 10 pg. 116.)

Sarum sequences can be found on the Sarum Chant website,
http://hmcwordpress.mcmaster.ca/renwick/missal/ (click link for sequences)

Thanks, Tom: I found the Music for Profitentes in a MS of Hymns, Tropes, & Sequences from S. Gall at e-codices. (What a wonderful resource!) I was afraid I'd have to try to transcribe it, but it seems that has already been done for me.

Missing post finally appeared...

"I am not sure that it is STILL allowed to sing a suitable song before the Gospel in the O.F. but a former sequence would be ideal."

It's not and I don't recall it ever being permitted.

Here's the 1975 GIRM - the reference to another option is not to "another suitable song" but to psalms or tracts from the LEctionary or Graduale:

37. As the season requires, the "Alleluia" or another chant follows the second reading.

a. The "Alleluia" is sung in every season outside Lent. It is begun either by all present or by the choir or cantor; it may then be repeated. The verses are taken from the Lectionary or the "Graduale."

b. The other chant consists of the verse before the gospel or another psalm or tract, as found in the Lectionary or the "Graduale."

38. When there is only one reading before the gospel:

a. during a season calling for the "Alleluia," there is an option to use either the psalm with "Alleluia" as the response, or the responsorial psalm and the "Alleluia" with its verse, or just the psalm, or just the "Alleluia";

b. during the season when the "Alleluia" is not allowed, either the responsorial psalm or the verse before the gospel may be used.

39. If the psalm after the reading is not sung, it is to be recited. If not sung, the "Alleluia" or the verse before the gospel may be omitted.

40. Sequences are optional, except on Easter Sunday and Pentecost.

RC

And I supplied the text of the prior (1975) version of the GIRM as well, which was in accord fwiw.

I would have thought the Vatican would be up to date, but then again...

Efficiency is apparently not a hallmark of the Vatican's telecomm services.

Unfortunately the Vatican website offers documents by language only,
Not by jurisdiction.
The English version happens to be the USA modified doc.
It only applies to the USA.

I like the old old way better.
The USA adaptations were provided in an Appendix.

The following volumes of the Analecta Hymnica are listed as containing sequences, 8, 9, 10, 37, 39, 40, 42, 44, 53, and 54.

I started at 54 and worked forward,
Trinity sequences
1. Laus Deo Patri (4 verses) AH 54 pg 23
2. Profitentes unitatem (18 verses) AH 54 pg 249
3. Patrem datum paracletum (18 verses) AH 54 pg 251
4. Quicunque vult salvus esse (8 verses) AH 54 pg 252
5. Vox clarescat, mens purgetur (6 verses) AH 54 pg 254
6. Jubilemus cordis voce (12 verses) AH 54 pg 255
7. Dulcis amor pax veritas (6 verses) AH 54 pg 256
8. Benedicta semper sancta sit trinitas (20 verses) AH 53 pg 139

Link here to sequence no. 8.
https://archive.org/stream/analectahymnicam5253drev#page/138/mode/2up

Full text (I have tried to correct the OCR typos but may have missed some)

81. De sanctissima Trinitate.

1 . Benedicta semper sancta sit trinitas,
deitas scilicet unica, coaequalis gloria.

2. Pater, filius, sanctus Spiritus
tria sunt nomina, omnia eadem substantia.

3 Deus genitor, Deus genitus,
in utroque sacer Spiritus deitate socius.

4. Non tres tarnen dii sunt ;

5. Deus verus unus est ;

6. Sic pater Dominus, filius
spiritusque Dominus.

7. Proprietas in personis,
unitas est et in essentia,

8. Maiestas par et potestas,
decus, honoraeque per omnia.

9. Sidera, maria continens,
arva simul et universa condita;

10. Quem tremunt impia tartara,
colit quoque quem et abyssus infima.

11. Nunc omnis vox atque lingua fateatur
hunc laude debita,

12. Quem laudat sol atque luna.
dignitas adorat angelica.

13. Et nos voce praecelsa nunc
onines modulemur organica cantica dulci melodia.

14. Eia et eia nunc simul omnes iubilemus
altithrono Domino laudes in excelso.

15. O veneranda trinitas !

16. O adoranda unitas!

17. Per te sumus creati, Vera aeternitas ;

18. Per te sumus redempti, summa tu Caritas.

19. Populum cunctum tu protege,
salva, libera, eripe et emunda.

20. Te adoramus, omnipotens, tibi canimus, tibi laus et gloria.

Oh... I found it!
It's actually way back in the appendix (2nd of 3 chants), listed under the Transfiguration.

Here is also a simple SATB setting that can be saved as pdf through the Print icon.

it didn't survive the Tridentine purge

Oh, goodness! What purge? The pre-tridentine Missal of the Roman Curia contained only two (or three?) sequences. Many other medieval uses were as shy as Rome as to the inclusion of sequences in their books. Other places, in turn, produced great number of this genre of chants, but most of them remained strictly local phenomena.

Thanks, Ney, for sharing that Trinity sequence and for that Franciscan Cantus varii. The CMAA site has an unrelated book by the same title from 1928.

I had a nightmare that I was permitted to be cantor for a Mass this past weekend and suddenly during the Mass I realized that there was a sequence coming up for which I had no music! Glad to wake up, but at least I went to Mass in my dreams.