Deep feelings of faith run through Mozart’s Mass in C Minor. Although the work remained unfinished, possibly because of an imperial ban on elaborate church music, its completed movements reveal the composer’s mastery of sacred traditions and inventive genius. John Butt’s recording presents the piece as it might have been heard at its first performance in 1783, with 16 choristers and a chamber orchestra of period instruments, but with the addition of three movements recently finished by the Dutch musicologist Clemens Kemme. Butt chose to record the piece with smaller forces than usually employed today. Mozart, he notes, probably performed Handel oratorios in Vienna with 16 singers, allocating two voices to a part in music for double choir. “This is close to the size of vocal forces adopted for our recording,” Butt tells Apple Music Classical. “The orchestral forces likewise approach Mozart’s norm for choral works in Vienna, with around eight violins.” The Dunedin Consort’s limber choristers, crystal clear and surprisingly weighty for their collective size, magnify the music’s intimate qualities. Butt was aided by what he describes as Kemme’s revelatory new edition. “The crucial thing for us was to have the best possible completion of the existing materials. His experience as an arranger, music theorist and historical musicologist is almost unrivalled for this period of music. He not only provides the most complete and idiomatic working of missing parts, such as the way the vocal parts are paired in the partially surviving ‘Osanna’ fugue [in the ‘Sanctus’ and ‘Benedictus’], but also the missing instrumental parts in the ‘Credo’ and the string parts in the extraordinary ‘Et incarnatus est’.” The work’s set-piece arias, with Anna Dennis on fine form in “Laudamus te” and Lucy Crowe supremely graceful in “Et incarnatus est”, are enhanced here by a raft of orchestral details. The double-choir “Cum sancto spiritu” and “Osanna” fugues, meanwhile, flow with joy, the latter preparing the way for C.P.E. Bach’s Heilig ist Gott, a compelling song of praise for alto and double choir. “Bach’s work was one of the most celebrated choral pieces of its time,” observes Butt. “Its double-choir texture was clearly the most obvious recent influence on Mozart’s composition of the Mass.” Butt directs listeners to sample “Et incarnatus est”, the highpoint of the Mass. “We almost palpably hear the most delicious of divine expressions somehow realised in an earthly context,” he says. “It’s almost as if he captures the divine element of traditional Catholic worship and makes it significant at the individual human level.”