Organum

Organum[a] (/ˈɔːrɡənəm/) is, in general, a plainchant melody with at least one added voice to enhance the harmony, developed in the Middle Ages.

Over time, composers began to write added parts that were not just simple transpositions, thus creating true polyphony.

The first document to describe organum specifically, and give rules for its performance, was the Musica enchiriadis (c. 895), a treatise traditionally (and probably incorrectly) attributed to Hucbald of St. Amand.

As key-concept behind the creative outburst that manifested in the 11th and 12th centuries is the vertical and harmonic expansion of dimension, as the strongly resonant harmony of organum magnified the splendour of the celebration and heightened its solemnity.

It is the composers' love for cantus firmus that caused the notation of the tenor line to stay the same, even when the methods of penning music were changing.

Cultural and intellectual life flourished in Paris during the 12th century with the University of the Sorbonne having become a reputed institution that attracted many students, not all of them French.

[citation needed] The construction of Notre-Dame Cathedral on the Île de la Cité took place between 1163 and 1238 and this period coincides with the various phases of development of the Paris style of organum.

The presence of Léonin and Pérotin at the Notre-Dame School made Paris the centre of the musical world in the 12th century.

Léonin, magister cantus of Notre-Dame, compiled the Magnus Liber Organi de Gradali et Antiphonario.

Léonin wrote organa dupla based on existing chants like the Alleluia and the gradual of the mass and responsory and Benedicamus Domino of Vespers for the major liturgical ceremonies in the yearly cycle.

Not only is it a compilation for practical use during mass and office compassing the ecclesiastic year, the first of its kind; it also introduces the use of the rhythmic modes as a creative principle.

Thus, in organum duplum of Léonin these compositional idioms alternate throughout the complete polyphonic setting, which is concluded in monophonic chant for the last phrase.

Note that organum purum is not possible in three-part organa, all three parts are modal and need to be organized according to the rhythmic modes.

Pérotin even went as far as composing two four-part organa (quadrupla), "Viderunt omnes" and "Sederunt principes" which were performed in Notre-Dame in 1198 on New Year's Day and in 1199 on the feast of St Stephen (a decree of Odon de Sully, Bishop of Paris, exists which stipulates the performance of 'organa tripla vel quadrupla') Apart from organa, Pérotin extended the form of the Aquitanian versus which was henceforth called conductus.

As the tenor in organa dupla in discant sections proceeds always in the 5th mode (all longs in a rhythmic group ordine), Pérotin, who was a generation removed from Léonin, saw fit to improve them by introducing different modes for the tenor and new melodic lines for the dupla, increasing the rhythmic organization and diversity of the section.

In turn, the motellus gave birth to the motet which is a poly-textual piece in discant, which obviously sparked a lot a creativity as it soon became a prolific form of composition.

There are arguments that support a relative freedom of rhythm in organa dupla but others who say that the interpretation of the music should always be according to modal or Franconian principles.

[full citation needed] In the range of forms of compositions found in the later two manuscripts that contain the Notre-Dame repertory (F and W2) one class of distinction can be made: that which is (strictly) modal and that which is not.

In monophonic song, be it chant or a conductus simplex by Perotin, there is no need to vary from the classical standards for declamation that were a rooted tradition at the time, going back to St. Augustine's De Musica.

As Parisian Organum is rooted in Gregorian chant tradition, it is categorized under Ars antiqua which is thus called in contrast to the Ars nova which embarked on new forms that were in every sense original and no longer based on Gregorian chant and as such constituted a break with the musical practice of the ancients.