Richard Rittelmann : MONTEVERDI VESPERS DUO SERAPHIM EMILIANO GONZALEZ TORO R. RITTELMANN REBUT CAPPELLA CLUNIACENSIS
Duo Seraphim (Isaiah 6:2-3; 1 John 5:7): Vocal duet leading into trio
The text Duo Seraphim ("Two angels were calling one to the other...") begins as a duet. When the text (which melds lines from Isaiah and the First Letter of John) mentions the Trinity, a third tenor joins. All three sing in unison at the words, "these three are one."
The position of the motet Duo Seraphim is disputed. The title page of the first print of the score suggests that they are not part of the Vespers, but intended as separate Sacred Concertos. However, their place in between the psalms indicates that they were intended to be part of the Vespers, but could also be performed on other occasions, such as at the court of the Duke of Mantua, Monteverdi's employer. Furthermore, there arise problems as to whether the motets may be antiphon substitutes, or antiphon supplements.