Monteverdi composed the music while musician and composer for the Gonzagas, the dukes of Mantua. The libretto is compiled from several Latin Biblical and liturgical texts. The thirteen movements include the introductory "Deus in adiutorium", five Psalms, four "concertato" motets and a vocal sonata on the "Sancta Maria" litany, several differently scored stanzas of the hymn "Ave maris stella", and a choice of two Magnificats. A church performance would have included antiphons in Gregorian chant for the specific feast day. The composition demonstrates Monteverdi's ability to assimilate both the new "seconda pratica", such as in the emerging opera, and the old style of the "prima pratica", building psalms and Magnificat on the traditional plainchant as a cantus firmus. The composition is scored for up to ten vocal parts and instruments including cornettos, violins, viole da braccio, and basso continuo. Monteverdi travelled to Rome to deliver the composition to the Pope in person, and a partbook is held by the Vatican Library.