My original exposure to the existence of the Quantz Sonata in A minor for Viola and Continuo came from a footnote in a history of the viola I read in my early years as a college student. In it, this footnote mentioned that the Breitkopf catalogue of 1762 indeed offered this sonata for sale at that time. Beginning in 1762 the publishing house of Breitkopf und Härtel (still in existence today) published a catalogue of all the music it currently had in print and listed each work in the catalogue with a small fragment of its opening measures. Periodically new supplements to this catalogue were issued up to 1787 and with the publication in facsimile of these, a veritable treasure trove of solo music for all kinds of instruments including of course the viola came to the attention of players and scholars alike. Among these was the A minor Quantz sonata listed as a 3 measure excerpt. All trace of the work was seemingly lost aside from this tantalizing incipit. However, with the publication in 1997 of a complete thematic catalogue of Quantz’s music the possibility of discovering the work’s existence grew. Sadly my initial searches here drew no mention of it, but on a guess I wondered since Quantz wrote largely for the flute and knowing many works of the time started their lives written for other instruments, I wondered if t may have been transposed from a nearby key as was often seen in the works of JS Bach and decided to look afresh in the catalogue for a flute version in G minor. And with this assumption I found it and at once realized that if one read the flute version at sight while imagining it in the alto clef it immediately transposed itself at sight to the key of A minor and in exactly the same register as seen in the Breitkopf excerpt of 1762, so there it was: the sonata could be reconstructed from the flute version and after I got a copy of that original manuscript on microfilm from the Prussian State Library, I was able to transcribe the viola sonata fully, amend the figured bass accidentals for the new key and create my own realization for the harpsichordist to play. It lies very well on the instrument and as we know could be purchased from Breitkopf in 1762.
Why would this work exist at all from a composer of almost exclusively flute music? Two reasons come to mind immediately. Firstly, the court of Frederick the Great where Quantz worked, was a beacon of the Enlightenment and increasingly works were written and played by great virtuosi and for a large variety of different instruments. Frederick had regular evening concerts and much music would have been demanded and consumed. The viola usually had the role of filling out harmonies in an ensemble so the usual viola player of that day did only that. Any solo repertoire would likely have been played by a violinist on the bigger instrument. I can imagine Frederick’s concertmasters, JG Graun or Franz Benda doing this since both composers left us multiple viola works which are quite virtuosic indeed and show techniques only an accomplished violinist could execute. So, one evening a Graun or Benda may have desired playing on the viola for the sake of variety and need something to toss off quickly. Transposing something at sight that may already have been heard might well have presented good possible repertoire choices to the performer and the flute sonata of Quantz in G minor was a fine candidate indeed. For the Keyboardist it is a simple thing to transpose from G minor to A minor at sight and in all likelihood that keyboardist would have been the great CPE Bach who was also employed at Frederick’s court.
My guess is that Quantz therefore did not actually write this viola sonata brand new but suggested a way in which a quick need for variety in an evening concert could be met by one of the virtuoso violinists at the court desiring to play on the viola and eventually, of course, this fine solution found its way into print in the 1762 Breitkopf Catalogue. In any case we now have yet another sonata from the Court of Frederick the Great and a real gem. It has a soulful deep first movement and two very vigorous virtuosic fast movements that follow. These exert considerable bowing and facility challenges to the violist and overall it is a truly virtuosic work. Indeed, with this newly uncovered work and many of the other compositions for viola from the Court of Frederick the Great one sees right from the outset that the tonal and technical peculiarities of the viola, only rediscovered in subsequent centuries, were then fully understood and assimilated into compositions of great beauty and appeal. This new Quantz sonata provides a welcome addition to the baroque repertoire for viola and should become a standard of concert programs in the years to come.