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Pope Saint Paul VI (3 April 1969): “Although the text of the Roman Gradual—at least that which concerns the singing—has not been changed, the Entrance antiphons and Communions antiphons have been revised for Masses without singing.”

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Views from the Choir Loft

Rehearsal Videos • “O Magnum Mysterium” (Victoria)

Jeff Ostrowski · December 7, 2015

953 O Magnum Mysterium Victoria IKE MANY of his fellow composers, TOMÁS LUIS DE VICTORIA (†1611) was a Roman Catholic priest. 1 His distinctive religious sensibility was apparent in his compositions, and a striking example is his setting of the Responsory for the Octave Day of Christmas:

    * *  O Magnum Mysterium (PDF)

I’ve created rehearsal videos for each voice to help amateur choirs. It can be a bit frightening to tackle such a masterpiece—and sometimes feels like “rushing in where angels fear to tread”—but hopefully these practice videos help:

EQUAL VOICES : YouTube   •   Mp3 Audio

SOPRANO : YouTube   •   Audio

ALTO : YouTube   •   Audio

TENOR : YouTube   •   Audio

BASS : YouTube   •   Audio

Renaissance composers frequently (but not always) left it up to the singers to add the sharps and flats. The rules for “musica ficta” are fairly straightforward, but—as many Renaissance theorists pointed out—problems arise when the various rules conflict.

Many editions of Victoria’s O Magnum Mysterium have a sharp for the Sopranos in measure 21 but a natural for Tenors in measure 20, even though they sing the exact same phrase. Here’s the Tenor line in a 1582 manuscript:

959 TENOR 1583b


There are reasons why Tenors might not sing a sharp—while the Sopranos do—but there are more compelling reasons why they ought to match. When I looked at a 1572 manuscript, I found that missing sharp for the Tenors:

958 O Magnum Mysterium Victoria 1572


Now I will reveal the “dirty little secret” about musica ficta: we prefer it how we learned it. In other words, we tend to prefer a piece the way we sang it the first time. For example, some editions have the Sopranos in measure 42 singing a natural—not a sharp—and there are compelling reasons for this; but in my edition, I keep the “traditional” way.

For those of you who know this piece, have you ever sung directly from the part book? Here’s how the TENOR would have been sung in the 16th century.



NOTES FROM THIS ARTICLE:

1   Cristóbal de Morales (†1553), Costanzo Porta (†1601), Lodovico Viadana (†1627), and Gregorio Allegri (†1652) were all clerics, and many more composers could be mentioned.

Opinions by blog authors do not necessarily represent the views of Corpus Christi Watershed.

Filed Under: Articles Tagged With: Tomas Luis de Victoria Composer Last Updated: January 1, 2020

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About Jeff Ostrowski

Jeff Ostrowski holds his B.M. in Music Theory from the University of Kansas (2004). He resides with his wife and children in Michigan. —(Read full biography).

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President’s Corner

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    Dom Pothier • Photo from 1904
    Dom Paul Cagin, in a 1904 publication (L’oeuvre de Solesmes dans la restauration du chant grégorien) made sure to include a beautiful image of Dom Pothier, the legendary abbot of St-Wandrille. Also shown is a very young Dom André Mocquereau. Auguste Pécoul—considered the spiritual “son” of Abbat Prosper Guéranger of Solesmes—wrote as follows on 24 June 1901: “To forestall any confusion, let us remember that there is just one Gregorian notation—that restored, according to the ancient manuscripts, by the eminent Abbot of Saint-Wandrille, Dom Pothier.” ✠
    —Jeff Ostrowski
    PDF • “3-Voice Motet” (Father De Laet)
    I believe 99% of our readers will recognize this hymn tune. Perhaps Father Edgard De Laet should have called it a ‘hymn’ instead of a ‘motet for three voices’—but he’s technically correct, since MOTET is defined as: “a short piece of sacred choral music, typically polyphonic and unaccompanied.” The even verses are for three voices, as you will see if you download the PDF score at #20245. The odd verses may be song a cappella SATB or unison with organ.
    —Jeff Ostrowski

Quick Thoughts

    PDF Chart • “Plainsong Rhythm”
    I will go to my grave without understanding the lack of curiosity so many people have about the rhythmic modifications made by Dom André Mocquereau. For example, how can someone examine this single sheet comparison chart and at a minimum not be curious about the differences? Dom Mocquereau basically creates a LONG-SHORT LONG-SHORT rhythmic pattern—in spite of enormous and overwhelming manuscript evidence to the contrary. That’s why some scholars referred to his method as “Neo-Mensuralist” or “Neo-Mensuralism.”
    —Jeff Ostrowski
    “Reminder” — Month of January (2026)
    On a daily basis, I speak to people who don’t realize we publish a free newsletter (although they’ve followed our blog for years). We have no endowment, no major donors, no savings, and refuse to run annoying ads. As a result, our mailing list is crucial to our survival. Signing up couldn’t be easier: simply scroll to the bottom of any blog article and enter your email address.
    —Jeff Ostrowski
    PDF • “O Come All Ye Faithful” (Simplified)
    I admire the harmonization of “Adeste Fideles” by David Willcocks (d. 2015), who served as director of the Royal College of Music (London, England). In 2025, I was challenged to create a simplified arrangement for organists incapable of playing the authentic version at tempo. The result was this simplified keyboard arrangement (PDF download) based on the David Willcocks version of “O Come All Ye Faithful.” Feel free to play through it and let me know what you think.
    —Jeff Ostrowski

Random Quote

“The Catholic liturgy has been overthrown under the pretext of rendering it more acceptable to the secularised masses.”

— Professor Louis Bouyer (writing in 1975)

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  • Dom Pothier • Photo from 1904
  • PDF Chart • “Plainsong Rhythm”
  • PDF • “3-Voice Motet” (Father De Laet)
  • PDF Download • “Hymn for 2 Voices”

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Corpus Christi Watershed is a 501(c)3 public charity dedicated to exploring and embodying as our calling the relationship of religion, culture, and the arts. This non-profit organization employs the creative media in service of theology, the Church, and Christian culture for the enrichment and enjoyment of the public.