Some remarks on rhythm in the compositions with poetic texts in the Liber Sancti Jacobi
The notation of the polyphonic repertories of the 12th century, Saint Martial and the Liber Sancti Jacobi, as far as we know, does not express rhythm. Consequently, studies and editions of the repertories by Brian Gillingham, Theodore Karp and others do not agree as to their rhythmic interpretation.
This paper deals with the pieces with Latin poetic texts in the Liber Sancti Jacobi, focusing on pieces which exist in the manuscripts in different versions. Closer examination of these and of the setting of the text of the conductus “Jacobe sancte tuum”, the only piece of the repertory with text not in syllable counting or rhythmic poetry, but in metric form, that is, in dactylic hexameters, lead to the conclusion that most likely the lower, main voice of such pieces in the Liber Sancti Jacobi should be sung in roughly equal values. The additional upper voice, if, as in most pieces, in florid counterpoint, should be coordinated to the main voice in a rhythmical free, not modal, manner, holding the concordant notes slightly longer, while the discordant ones should be treated as quicker passing notes. Such rhythmic differentiation within the ligatures might have lead to modal notation.