I recently heard a splendid Magnificat by Tomás Luis de Victoria that was said to be in “octavi toni”; I had heard similar phrases (such as “primi toni”) before, and this time I decided to get to the bottom of it. So I did some googling and wound up at Stack Exchange. The questioner asked:

In XVI century, there was a composer called Girolamo Cavazzoni. He wrote (amongst other pieces) a couple of Magnificats – in primi toni, quarti toni, sexti toni and octavi toni. [details and speculation omitted — LH] However, if the assumption above is correct, the octavi toni would end up in Ionian mode. Hence my question – could someone shed some light on the naming conventions of these times, and how is octavi toni different from primi toni?

A long and detailed answer began:

As you’ve probably deduced, the assumption is incorrect. In fact, this question is based on a couple of incorrect assumptions. The first is the identity of the first mode, which is Dorian, not Ionian. Ionian didn’t even exist when the modes were initially numbered and named.

The second is the relationship of the numbering scheme to the tonic notes. There are two modes per tonic, not one. This is possible because each of the modern modes corresponds to an authentic and a plagal mode. The authentic and plagal modes come in pairs that have the same tonic, but they have different ranges and different reciting tones (or “dominants”). In particular, the authentic reciting tone is a fifth above the tonic (sometimes a sixth in Phrygian), while the plagal reciting tone is a third above (sometimes a fourth in Hypophrygian and Hypomixolydian).

Now my attention was diverted to that word plagal, which I was sure I’d seen before, but (unsurprisingly, since I am not a musicologist) whose meaning I could not keep in my head. (For one thing, it reminds me of the Latin verb plangere ‘to strike; to bewail, lament,’ which turns out to be entirely irrelevant.) So I turned to AHD, where I found:


Of or being a medieval mode having a range from the fourth below to the fifth above its final tone.

[Medieval Latin plagālis, from plaga, plagal mode, from plagius, plagal, from Medieval Greek plagios (ēkhos), plagal (mode), from Greek, oblique, from plagos, side; see plāk-¹ in the Appendix of Indo-European roots.]

The definition is basically gibberish to me, but the etymology is interesting, especially when you go to the Appendix and discover that the Greek etymon also gives rise to French plage and Spanish playa ‘beach’! Maybe it will help if I think of the plagal modes as beach music.


  1. J.W. Brewer says

    FWIW, the Latin names for the eight tones are matched up with the Church Slavonic and (Byzantine) Greek names in a chart here:

  2. Jen in Edinburgh says

    A plagal cadence is a kind of ‘alternative ending’ for pieces of music – not as definite as a perfect cadence, which is the standard ending, but more definite than an imperfect one (which usually comes partway through, to finish a section and keep going). That might be where you’ve seen the word – I think it’s the only place I have.

    (Perfect is V – I (e.g. G to C) and plagal is IV – I (e.g. F to C), but I had to look that up!)

  3. That might be where you’ve seen the word

    I imagine you’re right; that phrase is familiar. (And I probably got it confused in my mind with “plangent.”)

  4. Thanks @Jen, yes. @Hat I wouldn’t be mislead by all that “Mediaeval” talk. Plagal cadences are alive and kicking all through the music known as Classical. known as the “Amen” cadence because of its use in many popular hymns.

    Here’s a random set of examples

    (And now I’m playing the Toccata & Fugue D Minor at full blast, waiting for the cadence. Delicious dissonances!)

  5. A detailed and relatvely clear discussion here, on StackExchange, with links to recordings.

  6. Thanks, those are all useful links.

  7. Humbled. All I know is that the notion of cadencia in tango dancing confuses the musicians, being nothing like cadence AND because the dance-specific meaning is missing from the dictionaries (I’m so lucky that tonality plays so tiny role in the dance – indeed, I don’t think a moving human body is even equipped to express pitch – and my handicaps with this side of music pass unnoticed lol)

  8. Plangent comes under plāk-² in the famous appendix.

    Yes, plagal cadences are in common perfunctory use in liturgical music; but they also occur for grandiosity at the end of large impressive “secular” movements. Well after the Baroque even, like Brahms Symphony 4 (first movement) and Tchaikovsky Piano Concerto 1 (first movement).

    Perfect is V – I (e.g. G to C) and plagal is IV – I (e.g. F to C), …

    That’s the standard story. In major keys the IV might be replaced by iv, the minor variant of the subdominant chord (F minor chord, in C major), for added effect. In minor keys i might occasionally be replaced by I, the major variant of the tonic chord (C major chord, in C minor) for an effect resembling the tierce de picardie. I can’t think of a published example of that second case but I’m sure it occurs. (I would use it in my own work, which is proof enough …)

    There are also plagal extensions of perfect cadences:

    VIVI in major, with VivI as a possible variant.

  9. Is it just me then who thought of a relation between “authentic” and “plag(iarism)al”?

  10. Is it just me …

    I’d perhaps be unrepresentative in having known ‘plagal’ as in cadence since school days — probably about the same time I learned of ‘plagiarism’. As per @Hat’s link (or look in etymonline) *plak- is wonderfully protean. In the sense flat: flag(stone), flake, fluke (as in flatfish), placenta, plank, … In the sense calm/subdued: placebo, placate, pleasant, …

    How would a cadence be inauthentic? I guess any musician can steal stuff; but cadences are building blocks like consonant clusters. Can’t copyright them any more than the modes.

  11. How would a cadence be inauthentic?

    Ah, there such a thing as a Deceptive cadence aka ‘suspended’ [**], ‘interrupted’, ‘false’. The composer lulls the ear into a false sense of nearly-resolution; then gallops off for another exposition.

    also frequently used in popular music. For example, the Pink Floyd song “Bring the Boys Back Home” ends with such a cadence (at approximately 0:45–50).
    [which is a kind of sardonic pause before getting properly acerbic certainly not “ends with”]

    “frequently” ? Other than that PinkF, they’re evading my Google-fu.

    [**] not to be confused with a suspended chord, of course. Which is indeed frequent in Jazz/bebop: Miles Davis, Herbie Hancock; Beatles ‘Long and Winding Road’.

  12. David Marjanović says

    The “root” is so “versatile” because it was reconstructed too sloppily. There are several suggestively similar PIE roots involved that may have something to do with each other but can’t be derived from each other by PIE means. Maybe start here

  13. If you’re thinking of the AHD appendix, they don’t reconstruct a single root — that’s why I said Latin plangere “turns out to be entirely irrelevant.”

  14. David Marjanović says

    Both roots, sorry. (And the short-vowel *plak- AntC brought up, if that’s not simply a supposed ablaut grade of one of the two long ones.)

    While I’m at it, I haven’t looked up if Watkins reconstructed any of them himself or if they’re simply taken from the IEW.

  15. ktschwarz says

    Yes, AntC’s “wonderfully protean” referred only to AHD’s *plāk-¹, not including *plāk-². David was saying that *plāk-¹ itself was really several things lumped together. In particular, Latin placēre (> English placate, pleasant, etc.) can’t be shown to belong to this root according to de Vaan, and the OED now follows that view.

    (The “short-vowel *plak-” isn’t meant to be any different from *plāk-¹, it’s just Etymonline dumbing down Watkins, just like he replaced all Watkins’s schwas with e.)

  16. I’m no specialist in his work, but I do have a favourite piece from Victoria. This four-voice Ave Maria motet gives a fine example of plagal cadence extending perfect cadence. The amen is articulated twice. In modern terms (not really appropriate for a Renaissance composition) it ends in E (E minor, but with a tierce de picardie so it finishes on a major harmony):

    [v (presented in fact as i of B minor) –] V IivI

    That spans from 1:12 to 1:24 in this exquisite performance. Sustained and repeated long notes bind the perfect to the plagal and give 12 seconds of cadence a lucent azure transcendence to be treasured in memory.

  17. Thanks for that!

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