The soprano begins alone with a descending and then ascending open fifth. This is followed, on the word ‘mysterium’ in the second part of the melody, by a recurring sequence of semitones, also moving up and down. The alto has already joined in canonically with the same melody. The fifth still lingers in the ear as the melody continues in semitone steps. Harmonised in a modally ambiguous manner and without a single third in the melody, this opening has something fascinating about it, even in the sub-sequent prolonged two-part texture. Every good melody simultaneously connects the past in im-mediate memory, the present in the sound at hand, and the future in the anticipated possibility.
Finally, the tenor and bass join in with the same imitative pattern. A four-part texture emerges. One briefly thinks one hears major chords, yet the harmony oscillates towards darker tones. The interval of up to two octaves between the soprano and bass creates a sense of mysterious expansiveness. Spiritual expansiveness allows one not to dwell too narrowly on what is evoked by religious symbols such as ‘incarnation’ or ‘virgin birth’ (a new beginning) here.
With ‘ut animalia’, a new, simple ascending melodic motif begins, first in the male voices, then in the female voices. Even the animals look up to see what has just happened and honour the ‘Dominum natum’.
In the polyphonic texture, the distinct fourth-note upbeat to the ‘iacentem in presepio’ theme also stands out. This upbeat fades away in the lulling setting of the word ‘presepio’ (manger).
A reverent pause draws attention to the Blessed Virgin and to a mysterious new beginning that surpasses all other births in wonder. In homophonic texture and with long note values, all voices begin together, taking up motifs that were already hinted at in the opening melody ‘O magnum mysterium’. At the musical climax, ‘Dominum’, one can hear in the soprano the symbolic setting of God’s descent into the world through the birth of Jesus Christ.
After the name of Jesus Christ is heard for the first time – the birth and coming of whom are, of course, being celebrated – the Alleluia follows in a completely new time signature (three-four instead of the previous four-four). Only a reversal and a new tempo can change the world. Yet even this mystically beautiful motet returns at the end to the old four-four festive rhythm, even though, musically concealed, the fifth from the beginning and the semitone sequences can still be heard as a reminder.
