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What’s an ictus?

August 11, 2011

Having titled this blog “The Ictus”, I hereby post an explanation of this subject in an off-the-top-of-my-head sort of fashion. 

From my Latin Dictionary: Ictus, us, m. : stroke, blow, hit; cut; sting, bite; wound; range; (musical or metrical) beat.  In conducting, the word ictus refers the part of your gesture that touches an imaginary horizontal plane (as if you were beating time on an invisible table).  

Side note: quoth Bilbo Baggins to his sword, after killing the spider: “Dabo tibi nomen, et vocabo te Ictus.” 


In the middle ages, the conducting of chant is thought to have been done in such a way as to show, not a metrical beat, but the shapes of the different groupings of notes.  The musical notation used to write down the chant did not show actual pitches, but instead consisted of various signs representing these conducting gestures.   (Side note: the study of these signs as found in old manuscripts or modern editions such as the Graduale Triplex is today known as semiology.)  The monks of the day memorized all their music, thus all the choirmaster needed to do was to consult the manuscripts with the notation to refresh their memories on details which would likely require particular attention.  The rhythm of chant at this time was free and very nuanced, partially out of concern for the distinct pronunciation of the texts. 

Thing went along this way with schola members memorizing the whole Graduale until c. 1000, when Guido d’Arezzo invented the system of solfege, and with it the musical staff.  This allowed the accurate notation of melodies, in such a way that for the first time one could look at a page of music and sing it without previously having learned the melody by heart.  The disadvantage of the revolutionary new system was that it conveyed less of the old rhythmic nuanced style.

In the late middle ages, the reigning pope asked Palestrina and some other Italians to produce a revised edition of the chant books.  Whatever committee that eventually got around to producing the new “Ratisbon” editions changed the melodies quite a bit to bring them in alignment with the current “correct” musical practices.  At this point, chant had gotten to be quite metrical, with different shaped notes having certain time values.  See an example book here.

Around 1850, there was discovered a manuscript which was basically a rosetta stone having old pre-staff notation with solfege written in underneath.  This set off a bunch of scholars on trying to restore Gregorian chant melodies to their older, uncorrupted forms.  Leading this revival were the monks of St. Pierre de Solesmes, France. 

Side note: Dom-this and Dom-that abound at Solesmes.  I think the way it goes is:

Dom Gueranger (1805-1875): refounds or revives the monastery

Dom Pothier (1835-1923: Vatican Graduale

Dom Mocquereau (1849-1930): Solesmes rhythmic method, with ictus, arsis, thesis, etc.

Dom Gajard (?): continues Mocquereau’s work

Dom Cardine (1905-1988): Semiology

The important result of all this new scholarship was that after 1903 when Pius X published his motu proprio Tra le sollecitudini and got the chant revival going officially, a committee was set up to hurry up and publish a Vatican Edition of the Graduale.  Although this committee consisted of a number of the leading chant scholars of the day, their collaboration gradually (pun) become strained, leaving Dom Pothier to pretty much finish things up the way he liked.  The Vatican Edition was published in 1908.

Finally, enter Dom Mocquereau.  He had edited the first Liber Usualis in 1896, and developed a practical rhythmic method informed by his extensive study of old manuscripts.  This rhythmic method utilized signs such as the ictus, horizontal episema, and punctum morae (dot).  With the addition of Mocquereau’s rhythmic signs to the Vatican Graduale, presto: we at last arrive at chant editions adorned with the ictus, such as we generally find them today.  The advantage of Dom Mocquereau’s system is that it provides a consistent interpretation of chant, whereas the unmarked Vatican Edition allowed considerable flexibility of interpretation.    This uniformity enabled chant to be taught easily to anyone interested, thus it became very widespread.  Download the Liber 1961 here.

A Summary of Mocquereau’s theory:

Every note-head gets one pulse, except for ones with the dot (or punctum morae, if you prefer) which get two pulses.  Notes with “expression” such as those under a horizontal episema (like a dash) get just a tiny bit stretched.

Logically, a stream of pulses can be counted as groups of two or of three.  The ictus just marks where you count one.  However, the ictus is only marked in certain places.  The unmarked ictus(es) can be deduced by four rules, as seen below in Fig. 1.

Fig. 1: An exerpt from the Parish Book of Chant

My experience with the ictus:

When I first came across these rules, being somewhat an excitable chap, I immediately began to mark any introit that we were going to sing with this ictus, according to these rules.  Knowing where this ictus was enabled me to conduct myself by making a circular motion with one hand, touching the good old imaginary table at every ictic note.  The interesting thing was, after a few weeks of this it became unnecessary to bother to mark up my scores any more, because I had acquired the knack of doing it on the run. (At least on pieces which I had run over once or twice to get the notes down – may I mention here that the ictus/counting thing is really most useful after one is able to sight read fairly well.) 

Sometime after I had become fluent in the ictus, I finally discovered this handbook of Gregorian Chironomy and got into the arsis/thesis and that sort of conducting, which is the whole point of having an ictus at all.

The ictus and semiology:

Now, the question is: what should I think of this ictus-y stuff given that newer methods don’t bother with it?  Semiology really doesn’t use it at all.

Here are some random thoughts:

  1.  The Mocquereau-style method of doing chant is what got me to the point where I could come up with an intelligent interpretation of any chant, including ones I had never heard, in a short amount of time.  
  2.  There is a clear method for the conductor to follow.
  3.  It helps to achieve smoothness and shaping. 
  4.  The counting does produce a consistent rhythm.
  5.  It also gave me a good default mode. 
  6.  Semiological nuances can be added onto this basic starting point.
  7. The ictus can be a reminder of things which are indicated in the semiology.
  8. Perhaps the ictus is best disregarded in syllabic chants, because it is completely independent of the word accent (known as the textual ictus, as opposed to the musical ictus we have been discussing). 

Thus far an explanation of the ictus, its place within the history of chant, its usefulness, how to place it, how I learned to use it, and some points for consideration.


From → Gregorian Chant

One Comment
  1. Maria permalink

    That was really very informative! Now how on earth do you explain how to sing the ictus? I have read only contradictory explanations. At best I have read it is a sort of landing, at worst it is neither a qualitative change nor a stress nor a lengthening. At its funniest it has been described as an imperceptible emphasis.

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