Organistrum / Symphonia  keyboard  in Santiago de Compostela cathedral.

Organistrum / Symphonia keyboard in Santiago de Compostela cathedral.

Symphonia / Organistrum


in Santiago de Compostela cathedral.


(Inquiry into a troubling problem of interpretation.

Analysis of possible solutions.)



In former articles I wrote both about different aspects of this problem and about practical means to build a replica of the instrument in order to make it work the best way. My aim is to match  not only with organological and technical subjects, but to  discuss musical ideas connected to them, in the way Music was considered as an art and as part of the mathematical knowledge of Nature, since Pythagoras to the Middle Ages and further.


Several researchers have already carefully examined the few witnesses related to this instrument. I am not going to repeat the whole list, I just want to offer here a short survey.

The sound box consists as usual in two oval parts plus the neck, there are three strings, 6 to 8 keys  within the half of the diapason, sound holes often in D shape. The keyboard mechanism  appears only once, in a 18th century copy (Gerbert) of a 13th c. deperditum  manuscript: 8 revolving keys and the list of the notes, from C to c (including Bb and B) are clearly visible. Three letters below the wheel might indicate a tuning: d, D, a

 A 13th century manuscript entitled “Quomodo organistrum construatur” illustrates the method to divide the monochord  into the eight stops of a diatonic scale starting from Ut.

No information about the use of the instrument is available. We can only guess it was played mainly for sacred music along the 12th century. Christopher Page, the only scholar who faced the problem of  the name: Symhonia / Organistrum, has several doubts and no definite answer.


We know that almost all depictions and witnesses belong to the 12th century, but  the year and the decade are mainly unknown.  Since it is impossible to follow an exact chronology it’s absurd to define an evolution of the instrument through these witnesses. I can just study carefully the features.

In Ahedo de  Butron (Burgos) sculpture, one of the musicians might be turning a crank with his right hand, while with his left hand forefinger he is actually touching the second string; the second musician is touching the third string with his right hand forefinger and with the other hand is turning the corresponding tuning key. There is no evidence of a keyboard (as in  Hortus deliciarum manuscript), and I guess the two musicians are just  tuning a large viella, since no crank and no wheel are there.

In Soria sculpture (Spain) we see only one string (?), no bridge, no wheel, no keys. The musicians look as they were actually turning a wheel and pulling the keys, but the damages suffered by this sculpture do preclude a clear observation of details. On the contrary  the similarly shaped instrument in Boscherville capital (France) presents  crank, tailpiece, wheel and  keys.

What was this wheel  intended to do, but to produce a continuous sound? This is the first observation with musical relevance in our description. Now, suppose we have built a large Viella, about twice the size of an usual one, with a wheel in it: one of the two musicians can stop the strings all along the neck with his fingers, but he is not at ease  cause his fingers interfere accidentally with the closest strings. To have a system of keys might be suggested. In some depictions they appear, 6 to 8 within the half of the diapason. They look like little bars passing beneath the strings (Boscherville and Vercelli) or simply protruding from a box that hides the mechanism. It is reasonable to think about a simple diatonic scale, but we can’t state the keys are touching either only one or more than one string.

The structure of the keyboard depends on which kind of music we are going to play.

Suppose we’ve got a musical instrument which can produce a continuous sound and we want to perform a simple melodic line with it, with drones accompaniment and at a moderate speed, the following sort of keyboard would be

Type 1:

Type 2: you want to play a melody in organum with drone accompaniment. You will provide the keys with double tangents to stop the treble and middle strings tuned a fifth or a fourth apart, leaving the bass string free, tuned an octave under the treble.

Type 3:  according to Gerbert’s drawing:

keys acting on the three strings simultaneously: a) to play in organum prallelum (?) b) to play very loudly a simple melody on  three strings tuned at the same pitch (?).

Type 4:  all strings tuned at the same pitch,  the tangents acting on different strings in order to play double stops within the octave:

Type 5: strings tuned in unison and octave, keys which can be lifted and revolved with tangents on three different positions at 90° around the axe in order to play double stops within two diatonic octaves:

 A tuning is more suitable in my opinion  because it respects both the guidonian gamut and the exachordal system, starting correctly from Protus plagalis.

Which of these  types is the best  has to be determined only considering what we know about 12th century music.

Geographic area includes Spain and France mainly, then England, Germany and Italy. We can guess that his instrument served the sacred music composed and performed in Benedictine monasteries. In fact the monks were developing a new technique in polyphonic singing:  the vox organalis   was no longer in parallelum,  disattending the rules given by Musica enchiriadis and Micrologus,  and became more free.  An instrument like the described “Two men lyre” could fit this kind of music, provided it is equipped with the suitable keyboard: a new instrument for a new repertory. In any case a very limited one, with a rather short life too: at the end of 12th century composers began writing sacred music for three and four voices, a repertory  that can be performed only by organs.


At the top of the Gate of Glory in Santiago de Compostela cathedral  magister Mateus sculpted a wheel instrument in the middle of the range of  24 Elders all around the Lamb, depicting a scene taken from the book of Revelation. This gate is dated precisely the year 1188. This sculpture differs from all others we have examined

  1. In the general shape
  2. In quantity and quality of decorations
  3. Having 11 keys within the octave.

The sound box consists in two perfect circles connected through  lobes and a rectangular box containing the keys. The length of diapason is equal to the circumference of circles. Four triangular sound holes with little holes at the edges are cut in the first circle. A large quadripartite rosette with vegetable decoration is carved in the second circle. A long interlace made of 11 knots and 12 spaces is cut all along the rectangular keyboard lid.

All these features are unique among all depictions of the instrument. In other articles I examined these characteristics in the light of musical theory, astronomy and cosmology of the time. In this paper I would like to focus on the interpretation of the keyboard with 11 keys within the octave, describing a possible reconstruction of it.

Many important scholars stated that this number indicates a chromatic division of the keyboard. They pointed out that no chromatic scale was in use during the 12th century, nevertheless they accepted the number as an absolute evidence concluding that this instrument could have been invented for transposition.

Actually, some other chances are conceivable.

Keeping the 11 keys as they are, we can design

  • a chromatic keyboard for melodic playing, as follows:

  • a different  solution allowing us to play discant –like polyphony: double stops within one diatonic  octave + a fifth

  • another mechanism allows to play double stops within two octaves chromatic scale, using keys which can be lifted and revolved, with tangents on three different positions at 90° around the axe. This could be an instrument actually able to transpose whatever two voices polyphony into any desired mode:

 We are performing XII century sacred music using thie former key mechanism, but  with  an  A, d, a tuning, with good results:

Please listen to musical example:

Read more on: 


This report gives rise to more doubts than certainties.

Santiago instrument looks as the more complicated version of the wheel instrument documented for few decades during the 12th century, whose main relevance was due primarily to the continuous sound produced by the wheel , secondarily to the keyboard mechanism. 

Anyone  is problematic.

For example, we use to make wooden wheels covered with colophony, but this is actually characteristic of baroque and modern instruments. Was it the same in 12th century?

Some of the 12th century “Two men wheel  lyres” might even lack the keyboard.

Keyboard can be melodic or polyphonic, using the diatonic guidonian gamut.  In a very special depiction, the Santiago de Compostela one, we can imagine an unusual chromatic scale being adopted. This could be the last step of experimentation.

Then, at the beginning of 13th century,  vocal compositions in sacred music became so complex  that the Organ only could provide the appropriate accompaniment.

Like many other instruments the “Two men lyre”  left the churches to assume a new role in secular music, becoming smaller, equipped with a more practical (melodic or polyphonic) keyboard and playable by one performer.





El 2 de julio ha sido reabierto el Pórtico de la Gloria a Santiago de Compostela.  Este extraordinario documento non para de nos maravillar. Fue evidenciada la POLICROMIA del portal aportando a todo el edificio una nueva luz resplandeciente.

Al mismo tiempo, NUEVOS estudios ha descubierto el concepto de POLIFONIA leÍble en las representaciones con istrumentos musicales de los venticuatro ancianos de Apocalipsis.

Los instrumentos están rapresentados en parejas de dos (dos arpas, dos laúdes) y esto puede referirse a ejecuciones musicales duplices, y el teclado cromático del así llamado Organistrum, a la cumbre del pórtico, sugiere un progreso muy avanzado de la teoría musical a Compostela al final del siglo XII.

Por otro lado, las composiciones a dos voces del Codex Calixtinus testifican el trabajo hecho para el desarrollo de  la polifonía en la misma época.

En nuestros estudios hemos demostrado que el instrumento en la cumbre del Pórtico es verdaderamente singular, DIFERENTE de cualquier otro que conocemos. Su gama cromática, inútil por la música sagrada da la época, nos sugirió la creacion de una TECLA POLIFONICA que sirve al repertorio especifico del siglo XII. Si las viejas  "Lyras a dos hombres" con su escala diatónica, podían quizás acompañar las polifonias simples describidas en "Musica enchiriadis" y "Micrologus", el instrumento de Santiago representa una mejora, un heraldo de una música nueva: Conductus y Motetus , asi come el "canto nuevo" de la Apocalypsis).  Esta prospectiva nos enseña debajo de una luz nueva todos los instrumentos del Pórtico: el hecho que sean representados en parejas no responden simplemente a necesidades de naturaleza coreográfica, indican en realidad un pensamiento polifónico nuevo.

De manera similar la nueva restauración restituyó al Pórtico los colores originales, aportando una luz nueva a la intera obra.

(Thanks to Alejandro Gangui for original pictures of the Portico)

Para ahondar estos temas miren los blogs :








On 2018, July 12th the famous Gate of Glory in Santiago de Compostela has been re-opened. This extraordinary document of art and thinking still leaves us astonished and admired. The many colours of the original gate have been partially restored, giving a new look,a new surprising light to the monument.

At the same time NEW researches have revealed that a polyphonic experience lies behind the depictions of musical instruments in the hands of the 24 Elders of the Apocalypse, all around the arch.

All instruments are depicted in couples (2 harps, 2 lauds ...etc.) suggesting they can be played in duet. The so-called Organistrum, at the top of the arch, played by two musicians, shows a chromatic scale, thus indicating a possible extraordinary evolution in musical thinking at Santiago de Compostela during the 12th century.

Then, two-voices compositions in Codex calixtinus witness the developement of Polyphony at Santiago in the same age.

In our studies we have clearly demonstrated that Portico de la Gloria top instrument is a SPECIAL ONE, different from any other "two men lyre" known. In fact, its chromatic scale, quite useless for sacred music at that age, has suggested us the creation of a POLYPHONIC KEYBOARD that serves perfectly 12th century  new polyphonic repertory. If the first "two men lyre" with its diatonic scale could help may be accompanying simple polyphonies such as those discribed by "Musica enchiriadis" and "Micrologus", SANTIAGO's INSTRUMENT is the improvement of it, the herald of a new musical world.

This shed a new light over the whole Portico della Gloria music instruments setting: the couples are actually showing a polyphonic idea, not following only a sort of scenical arrangement.

Such as nowadys "chromatic restoration" of the gate: everything there shines in a better light !


please watch to our videos: 









Subscribe to this RSS feed