A singular use is sometimes made of obbligato violins in the serenade (185,,203, 204, 214, 215, 237, 239, 250, K.). After the first allegro, the solo violins lead in three movements, viz.: andante, minuet, and allegro (rondo, 250 K.) which are in a measure complete in themselves, and form, apart from their surroundings, a complete symphony. The expression "finalmusik," which frequently occurs in Mozart's letters, seems to prove that these lengthy compositions, with their concerted solo instruments, formed the conclusion of the concert. The "concertantsymphonie" of the two last serenades belonging to 1774 and 1775 (204, 250, K.), are conspicuous from their peculiar instrumentation. In the other movements the usual oboes, horns, and trumpets are used as accompaniment to the obbligato violins, flutes, horns, and bassoons, and in the last movement especially the combination and treatment are quite modern. These two serenades show altogether a marked improvement on the earlier ones, which do not essentially differ from symphonies. The orchestra is firmly handled, and the orchestral subjects freely elaborated. Each of the many movements of the last serenade is worked out as carefully and lovingly as if it were the only one, and the ideas and motifs are so full of meaning and of jovial good-humour that it is impossible not to feel that Mozart has here put forth his best powers. A short serenata (239 K.), consisting of a march, minuet, and rondo, interrupted by a short adagio, was written in January, 1776, for stringed instruments and drums only. A sort of chorus of two solo violins, accompanied by violas and violoncelli, is opposed to another, composed of two violins, viola, and violoncello, with the drums, all treated as tutti parts. Such admirable use is made of the contrast and combination of the two choruses, of the tutti parts and of varied sound effects, such as _pizzicato, &.c_., and even the drum is so skilfully employed, that this little work has taken a highly original colouring; with true tact the separate movements are made short, in order that the {SERENADES--CASSATIO, 1771.} (303) singular charm of the piece may not suffer from the fatigue of the ear.[36]