The features that come out increasingly in the Salzburg divertimenti - the individualization of tone, the chamber-musical refinement of the writing and the expression and the symphonic breadth of the forms - all this is realized in the Vienna serenades in a synthesis of styles and traditions that takes a different shape in each work. The first of the “series” is the Serenade, or, as the autograph manuscript reads, “Gran Partitta” K. 361 (370a). It was followed by K. 375, written in October 1781 for the sister-in-law of the court painter Joseph Hickel for St. Theresa’s Day (15th October). K. 375 returns to the normal serenade plan of five movements as against its predecessor's seven, and is written for a more modest-sized ensemble; in sound, however, it is no less symphonic than the older sister-work, and compensates for the reduced tonality of its scoring by stricter motif work and further refinement of the writing. Mozart was keen that the work should please the valet and personal cellist of the Emperor, Herr von Strack - Mozart knew von Strack himself, who was a frequent guest of Frau Hickel - and it was chiefly for this reason that he wrote it “with a modicum of good sense”, as he termed it. The original version was scored for two clarinets, two bassoons and two horns; the composer added two oboes in July 1782, A ten-part arrangement, which may be even later in date, with two cor anglais, has been lost.
Mozart’s last wind serenade, the “Nacht-Musique”, as he calls it in a letter, belongs absolutely among the most subtle chamber music of the mature composer. K. 388 was written at the end of July 1782 for the private orchestra of either Prince Schwarzenberg or Prince Liechtenstein. It was not without reason that Mozart subsequently (probably in 1787) chose to arrange this work as a string quintet, for the musical substance and design were able to remain almost unchanged: here, instrumentation and tone-colour retain only minimal intrinsic value: they are merged for the most part in the exceptional strictness of the writing. The four-movement form of the work, even moreso the canonic minuet, which is quite out of place in a serenade, is pure chamber music. The most sophisticated and profound territory of Mozart’s music is occupied by the uncompromising, almost overloaded strictness of the musical language and the unrelentingly sombre atmosphere that permeates the entire work (note that the key, C minor, is that of the Mass K. 427 and the Piano Concerto K. 491), only giving way at the last minute, in the coda of the finale, to a cheering C major outlook on to traditional Serenade pastures.