This edition represents the culmination of some eleven or so years of extensive research. It brings an exhaustive understanding of eighteenth-century practices and Mozart's stylistic habits to bear on the unfathomable task of replicating Mozart's style without impinging upon the tone of the work. The rigour with which Clemens Kemme has produced this edition of Mozart's abandoned mass is nothing but exceptional.
Mozart left the C minor mass as a torso. Of its twelve existing movements, only eight are fully complete: the Kyrie and the following seven parts that constitute the Gloria section (‘Gloria in excelsis Deo’, ‘Laudamus te’, ‘Gratias’, ‘Domine Deus’, ‘Qui tollis’, ‘Quoniam’ and ‘Jesu Christe – Cum Sancto Spiritu’). Two movements of the Credo section (‘Credo in unum Deum’ and ‘Et incarnatus est’) exist as Hauptstimmensatz drafts in Mozart's hand which give the main melodic lines, counterpoint, bass line and occasional orchestral details. These movements are not realized in their entirety. The sources for the ‘Sanctus’ and ‘Benedictus’ are Mozart's wind and timpani score (for the ‘Sanctus’ only), a set of trombone and organ parts by Hofstätter and Estlinger – two Salzburg copyists with whom the Mozarts worked frequently – and a manuscript copy of the whole work made by Matthäus Fischer. Fischer was an organist and choirmaster in Augsburg, where, following the dispersing of Leopold's estate after his death in 1787, the original performance materials ended up. It is believed this copy was created from the set of parts used in 1783 before they were lost. Only the Benedictus lacks a direct correlation to an existing primary source in Mozart's hand.
Being such an ambitious mass setting even in its incomplete state, it is likely that Mozart initially planned further movements. The reasons these never materialized are unknown: this is one of the work's many opaque facets. Previous examples of Mozart's longer masses (k139 and k66) subdivide both the Gloria and Credo sections into seven parts each. Given the expansive preceding seven-part Gloria section in k427, a similarly balanced Credo may at some stage have been intended. So far as we can glean, there was never an extant Agnus Dei, though a ‘Dona nobis pacem’ sketch exists from this period and is believed to have been destined for the C minor mass. Clearly this was abandoned during the composition process.
In editing a new performing version of the C minor mass, one is therefore faced with a choice between two options: completing only those movements that Mozart left unfinished or completing the mass setting in its entirety. The latter option would involve adding ‘Et resurrexit’, ‘Et in Spiritum Sanctum’, ‘Et unam sanctam catholicam’ and ‘Et vitam venturi saeculi’ movements to complete the Credo part of the mass. The ‘Agnus Dei’ and ‘Dona nobis pacem’ would then follow the ‘Benedictus’ and ‘Osanna’. Kemme has opted to try his hand only at the movements for which we have ‘substantial source material’ (vii). Thus all reconstructive efforts are concentrated on those final four parts: ‘Credo in unum Deum’, ‘Et incarnatus est’, ‘Sanctus’ and ‘Benedictus’. The decision not to flesh out a full mass setting also reflects both liturgical and practical evidence that the performance at St Peter's Abbey Church in Salzburg on 23 October 1783 omitted the Credo altogether – obviating the need to add movements in the name of ‘completion’ (see page viii of Kemme's Preface for a brief overview, and David Black, ‘Mozart and the Practice of Sacred Music, 1781–91’ (PhD dissertation, Harvard University, 2007)). Kemme's new edition therefore embraces both the specific performance history of k427, as well as its existence today as a musical work with its own aesthetic autonomy.
So what does this edition offer which previous editions do not? Over the years, new versions have typically been justified on the basis of recently discovered sources or new attempts to complete the mass setting. Kemme's edition is one of sensitive refinement rather than substantial overhaul. His skill as a professional arranger is brought together with a fastidious study of the styles, influences and practices that Mozart was concerned with around 1782 and 1783. This contrasts with previous versions where movements from early mass settings by Mozart are used to ‘pad out the gaps’, misunderstanding the ambition and grandeur of the C minor mass. The result is a version of the C minor mass which breathes more naturally than any of its predecessors.
For any aspiring completer, perhaps the most exposing moment of the work is the ‘Et incarnatus est’. The two violin and viola parts are a completely blank canvas from bars 19 until 113 (out of 119 bars total). It seems that Kemme believed Mozart must not have planned anything of particular melodic significance for the strings beyond the opening and closing passages. Given the relative completeness of the solo soprano line, the three solo wind parts and the bass line, this seems a credible hypothesis. Whilst certainly understated, Kemme's string accompaniment complements the shape of the ‘Et incarnatus est’, organically articulating the moments of tension and ease in the four solo parts. The subtle variation of rhythmic patterns – sometimes lilting against the regular bass line (bars 25–28 or bars 74–76, for example), at other times just providing harmonic tension on the beat (bars 41–52) – is where Kemme gives the upper strings their expressive range. In no way, however, does this mean that these string parts are dull: each part has character and elements of fleeting countermelody. The muted upper strings and the addition of two horns – both editorial interventions – complete the reflective ambience of this movement.
After ‘Et incarnatus est’, Kemme's crowning achievement is his work on the ‘Osanna’, an eight-part double fugue concluding the Sanctus movement. It is reconstructed with an even distribution of entries across the eight parts, standard practice in most fugues by J. S. Bach, and with each pair of subject entries occurring within the same choir. Kemme cites works by Antonio Caldara and J. C. Bach as models of similar eight-part counterpoint, though the suggestion that Mozart was likely to be familiar with these specific pieces would benefit from more detail, as the brief endnote on page x offers tenuous links rather than documented connections (though, of course, Mozart's relationship with J. C. Bach is well known). Regardless of whether Mozart knew those works, having the subject pairs within each choir makes the writing much neater and more logical than in previous reconstructions, which typically split the pairs between the two choirs. Kemme's method also enables each of the eight parts to have at least one entry of each subject – desirable in a fugue, and something that previous editions had not achieved. This redistribution of the fugal material makes the ‘Osanna’ fugue a much stronger and more convincing piece of counterpoint. It also emulates Mozart's use of the double choir in the ‘Qui tollis’ movement earlier in the mass, where each choir is distinctly defined, as opposed to being an amalgamated eight-part choir. Further, it connects with J. S. Bach's significance to Mozart at this time, as Mozart had recently gained access to a variety of his works (including the B minor mass) through his association with Baron Gottfried van Swieten from 1782 onwards.
Kemme applies the same level of care and diligence shown in his ‘Et incarnatus 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 skilful and insightful interventions at every stage. The outcome is a highly refined and elegant take on the C minor mass as Mozart left it.
The full-score publication comprises a detailed Preface, the score itself and a very valuable Critical Report. The Preface airs a broad range of subjects associated with the work, no doubt distilling Kemme's PhD thesis into the briefest possible essay. The reader is informed on a variety of matters relating to the sources, Kemme's processes, Mozart's stylistic influences, and speculation on the work's origin and why it was unfinished. Kemme also lays out his thoughts on performance issues, as well as general editorial matters. Throughout the score, all editorial changes and reconstructive elements are presented in greyscale, while any material from an original source is in standard black print. This is an elegant editorial solution, marrying practicality of real-life use in performance with immediate separation of material for scholarly perusal. The Critical Report offers detailed information on each of Kemme's sources before providing an index and commentary on every editorial decision made throughout the publication.
It is curious that Mozart's two most celebrated sacred works today are those which he never finished. His many other discarded works do not capture the interest and imagination of musicians, scholars and audiences in quite the same way. We know enough about the Requiem to state confidently how the work came about, what it was for and why it was not completed. By contrast we know very little about the C minor mass. Whatever Mozart's intentions for k427 were – and whatever the cause of its abandonment – Kemme's edition, in its bold embracing of this incomplete knowledge, is a welcome and much-needed addition to a long tradition of approaches to the C minor mass.
