In his early youth, Mozart had been extraordinarily clever at mimicking different musical styles; he could find the right idiom for an opera seria just as easily as for a Viennese symphony. By 1788 his composing technique had become so superb, his intellectual grasp of the musical material so sharp, that he was able to introduce all sorts of unexpected procedures into his chosen style without compromising its integrity. So, in K563 he adopts the light, engaging divertimento manner as a starting point for all six movements, but in each case introduces some surprises that have the effect of enriching and deepening the music.
In the first movement, the opening theme and the regular, balanced second subject, with violin and cello singing sweetly in parallel sixths, both suggest a popular style, as do the alternating passages of brilliant passagework. But the way these passages are shared out among the three instruments, creating constant variations of texture, the way even this passagework is composed of salient motifs, and the constant flow of subsidiary ideas, give to the music a rich inner life. It was this plethora of invention that many of Mozart’s contemporaries found difficult to follow, and the development section of this movement can still sound startling, beginning with a series of remote modulations that deeply disturb the tonal equilibrium, and continuing with the most intense three-part counterpoint.
The ‘Adagio’ has the atmosphere of a nocturnal serenade, with its elegant melodic lines and rich textures created by violin or viola double-stopping. After the first movement, with its large number of different motifs, we notice how the opening cello figure, rising through the notes of an A flat major chord, dominates the discourse. On its second appearance, transferred to the violin, it is ornamented with the range of its second phrase extravagantly increased. This elaborated version, returning for one last time in the extended coda, provides the movement’s climax.
The first of the two minuets is an energetic piece, beginning with emphatic cross-rhythms, and, like the first two movements, it is based on an idea that features the notes of the tonic chord. Mozart is both systematic and imaginative in the way he shares out evenly the role of the leading voice; K563, indeed, initiates a democratic style of string writing of which he was to make use in the three ‘Prussian’ quartets and the two late quintets.
The Divertimento’s three final movements have a lighter, more popular tone than the first three: the ‘Andante’ variations based on a simple, rather old-fashioned theme; the second minuet, with its hunting-horn motif; and the folk-like melody of the rondo finale. Yet in each case, Mozart’s sophistication breaks through almost immediately. In the ‘Andante’ the theme, with its two repeated sections, is played alternately in two-voice and three-voice settings; this initiates a movement in which, instead of the usual note-for-note repeats, we constantly alternate between different variations. Especially beautiful and noteworthy is the minor-key variation, composed throughout in three-part invertible counterpoint (three melodic lines that will fit together whichever of them is the top, middle, or bass). The second minuet is provided with two trios (so that the form is ABACA rather than the customary ABA) and a coda. The first trio is a memorable waltz-like episode featuring solo viola and including a dreamy section where the harmonic movement comes to an almost complete standstill.
If the Divertimento as a whole seems to sum up the state of Mozart’s compositional art in 1788, the final ‘Allegro’ points towards the brief future that remained for him. It’s not the first appearance of this type of simple pastoral melody (earlier examples include the Divertimento K334, the Oboe Quartet K370, and the G minor Quintet K516), but the style becomes more important and more strongly defined in the finales of his last years—in the Piano Concerto K595 and the Clarinet Concerto K622, for instance. Like the string trio movement, these suggest a romantic atmosphere of space and openness. But Mozart hasn’t finished with contrapuntal fun and games, either; the contrasting rhythmic motif, sounding quite trivial on its first appearance just after the opening melody, later appears in elaborate and witty canonic form, giving the whole movement a powerful injection of high spirits.
from notes by Duncan Druce © 2001