In the spring of 1787 Mozart had just returned to Vienna from Prague, where his opera Le Nozze di Figaro was a monster hit, and brought back a commission to write another opera (Don Giovanni, as it turned out) for an October Prague premiere. One major opera being not enough to occupy Mozart for half a year, he wrote the C-major String Quintet and much other of instrumental music. Mozart usually composed for specific buyers or performances, but no evidence survives of any such intended market for his mid-1787 works. A year later, he had trouble selling the C -major Quintet, and two others, by subscription, announcing in a June 1788 advertisement that because the number of subscribers was still very small, he had to postpone publishing the quintets until the following January. The market for music may have been already depressed by the outbreak of war between the Austria and Turkey in March 1788, and the recession the war caused.
The C-major Quintet is a confident, expansive work. The first movement’s first theme is explored at unusual length before the second theme makes an appearance, serving notice that this will be a large-scale work. The minuet’s irregular phrasing – its main section alternates phrases of four and six measures – would make it undanceable. Its middle section is more normal rhythmically, if tonally unsettled by 18th-century standards. The Andante’s extended dialog between the first violin and first viola has the atmospheric feel of an operatic duet, which might be expected from a composer in the middle of composing two of the greatest operas ever written. The finale begins as if it were a serenade or divertimento, with the first violin taking the melody and everyone else along for the ride, but the texture constantly changes as the other instruments insist on some share of the limelight, and the counterpoint gets fairly involved.
-- Notes by Howard Posner