Monteverdi’s Setting of Nisi Dominus (1610)
In each of the psalm settings of Montverdi’s 1610 Vespers the varying contexts of the cantus firmus (in each case, the psalm tone) help to define the structure of the psalm itself. The simplest organization is found in the cori spezzati setting of Nisi Dominus, which exhibits a continuous cantus firmus (sixth tone with finalis f) in the tenor part of each of the two five-voice choirs. Each statement of the psalm tone begins with its intonation, offering Monteverdi enhanced opportunities for harmonic variety in setting the chant. Although the cadential organization of each verse is similar, the bass underlying each statement of the pslam tone presents considerable variety.
The chant itself varies rhythmically from long notes to the same shorter notes as appear in the other parts, and a little more than half way through, at Sicut sagittae (verse 5), the tone is transposed up a fourth, allowing harmonzations with B flat minor and G minor chords in contrast to the predominating F major and D minor triads of the preceding verses. At the same point, the meter shifts to triple time, introducing a further variant in both the cantus firmus and its polyphonic content.
The varied context of the cantus firmus depends not only on its harmonization and rhythmic organization, but also on the polychoral patterning of the other four voices. Monteverdi’s opening verse combines both choirs in a densely imitative texture, but thereafter the two choirs alternate as strict cori spezzati (which overlap at verse endings and beginnings) until mideway through verse 6, where the choirs rejoin to end the psalm. The cori spezzati section (verses 2-6) reveals a gradually growing level of rhythmic excitement and ultimately textural density as the two choirs merge.
The doxology of a polyphonic psalm is often set somewhat apart from the psalm proper. In Nisi Dominus, Monteverdi not only returns to the original duple meter, but in the Gloria Patri also transposes the psalm tone down a fifth (from B flat to E flat) allowing for harmonization by E flat major and C minor triads. In many psalms, the Sicut erat in principio (“As it was in the beginning”) is a musical pun, reflecting the first verse in keeping with the meaning of the text, and in Nisi Dominus Monteverdi returns to F and reiterates the opening verse, giving a rounded stucture to the psalm.
[Excerpted from The Monteverdi Vespers of 1610: Music, Context, Performance by Jeffrey Kurtzman. Oxford and New York: Oxford University Press, 1999, pp 207-208.]