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The “Liber Generationis” from Trent CODEX 91

Project leader: Amina Fiallo

The Liber generationis is a three-voice polyphonic piece based on the opening of the Gospel according to Matthew (Matthew 1:1-16), which outlines the genealogy of Christ. It is contained in the Trent Codex 91 (Trento, Castello del Buonconsiglio. Monumenti e collezioni provinciali, ms. 1378, ff. 107v-111r), compiled by Johannes Wiser, chapel master at the cathedral of Trento in the 1460s.

The piece is part of a repertoire characterized by the cantus firmus written in equal notes, known as monorhythmic cantus firmus or per notulas notation, widespread from the late 15th century in many Germanic manuscripts. This repertoire is a very simple and formulaic liturgical polyphony, adaptable to various occasions. The genres most commonly notated with this technique are especially Introitus, Kyrie, Sanctus, and sequences—versatile genres that could be used in both canonical and votive masses. This repertoire is frequently copied in “usage” codices, personal miscellaneous manuscripts that chapel masters or students used to note music for various occasions (including the Trent codices).

The Liber is unique within this repertoire; there are no other polyphonic intonations on Gospel tones in the manuscript, nor in other codices of the same period from the same typology and geographic area. Additionally, unlike other genres with monorhythmic cantus firmus, this piece was sung on a specific occasion—the Christmas Matins.

The piece is highly formulaic, and the polyphony built upon it is very simple, almost always homorhythmic. The voices of Superius and Contra are constructed on the Tenor voice, which carries the cantus firmus. The piece consists of forty phrases that narrate the genealogy of Christ from Abraham to Jesus, characterized by four melodic formulas (α, β, γ, δ) that always follow the same order.

A complete performance of the piece would last about 25-30 minutes. It was therefore decided to compress it following this scheme, grouping the phrases with the same melodic module and overlapping their texts. Each of the three sections of singers is divided into three subsections, each pronouncing a different text—or more accurately, pronouncing the genealogy text from a different point, as shown in the scheme. The choir is further divided into a semichorus (which performs the parts indicated in blue in the figure) and the schola (which performs the parts in red, in plainchant, in response to the semichorus). The phrases beginning with “Iosias,” “Et post transmigrationem,” and “Iacob autem” are presented without textual overlaps, to preserve the key points of the narrative.

The piece is written in tactus alla breve: however, in the transcription, the note values have been divided, using a semibreve per measure, to make reading in modern notation easier. The ligaturae indicated in the manuscript have been preserved, with consideration given to how the text is applied. Medieval and Renaissance theory, deriving from the neuma-syllable relationship (typical of Gregorian chant), posits that each ligatura corresponds to a melisma. In later repertoires, especially those notated in manuscripts like Trent 91, ligaturae were often used as a means to expedite writing and clarify rhythmic notation; additionally, the text was frequently applied only to the voice carrying the cantus firmus, not to the added voices. Consequently, in the edition process, it may occur that the ligatures were not considered in applying the text to the notes in the Superius and Bassus parts.

The result of this project is a transcription firmly grounded in the analysis and critical study of the source, while addressing the needs of concert performance. The “concert version” proposed by the ITER Research Ensemble clarifies the structure and constructive logic of the piece, emphasizing its formulaic structure. It also addresses the challenge of presenting a piece that is difficult to perform in its original form, using a “cinematic” technique to compress the time without compromising the narrative flow.

In this version, the piece was first performed in Milan (Church of St. Ambrogio) on December 15, 2022, during the first public concert of the ITER Research Ensemble. Since then, it has been an integral part of the multimedia performance Chants, Places, Sources. Microhistories in Vocal Polyphony.

Media

An introduction to the piece by Amina Fiallo.
ITER Research Ensemble at work on the concert version of Liber generationis.