The Dutch music theorist, arranger, and musicologist Clemens Kemme closes the gap in this work by creating a new supplement, creatively and profoundly grounded and giving due respect to the composition, hence fulfilling that part of Mozart’s vow after more than 200 years.

This version is published by Breitkopf, complete with performance material, piano reduction, and study score. The edition is based on a meticulous re-examination of the sources for the completed sections and offers

• Addenda validated by authentic material

• New orchestration of the two “Credo” movements modeled on Handel and Bach as well as on Mozart’s own music, e.g., the aria “Se il padre perdei” (Idomeneo)

• Reconstruction of the “Sanctus” for double chorus from secondary sources and models by Caldara and J. Chr. Bach

• Sections added in the study score clear at first glance from their gray resolution

• Preparation of the edition in close collaboration with Frans Brüggen

• First performance of the version in 2006 by Brüggen with many subsequent performances, such as by the chorus of the Bavarian Radio under Peter Dijkstra (together with CD production)

“Kemme applies the same level of care and diligence shown in his ‘Et incarnates est’ and ‘Osanna’ reconstructions throughout the score, though these two movements truly set this edition apart from its predecessors. Careful awareness of eighteenth-century music theory and practices facilitate skillful and insightful interventions at every stage. The outcome is a highly refined and elegant take on the C-minor mass as Mozart left it.” (Peter Keenan, Eighteenth-Century Music)