Symphony No. 20 in D major, K. 133, was composed by Wolfgang Amadeus Mozart in July, 1772, when Mozart was sixteen years old. This symphony is one of many written during the period Mozart stayed in Salzburg, between two trips to Italy.
Compared to other symphonies Mozart wrote in this period, the scoring is extravagant, featuring two trumpets in addition to the standard oboes, horns, and strings. The key of D major, which is a key often reserved for triumphant or pompous music, is well suited to the presence of these trumpets.
The symphony has four movements: Allegro, Andante, Menuetto (Trio)
Though Mozart himself did not label the tempo of the fourth movement, it can be safely assumed by the character of the piece and the standard symphonic form of the time that Mozart intended the piece to go at an “allegro” tempo.
The first movement, in D major, is written in sonata-allegro form, with a twist. It uses a trick which Mozart used sparingly, but very effectively, during his career. The recapitulation is the mirror image of the exposition. That is, the recapitulation starts with the second theme, and Mozart waits until the very end to unveil the return of the first theme. He does so to great effect, first bringing the theme in softly with the strings, and then once again, gloriously doubled by the trumpets. This movement is full of grand flourishes, trills, and tutti chords; that is, it is filled with the pomp one would expect of an 18th century allegro symphony movement with trumpets.
The second movement, in A major, features strings with a solo flute, which typically doubles the first violin one octave higher. The violins play with mutes throughout the movement, and the bass part is played pizzicato. These features, in combination, give the movement a delicately thin texture that allows a beautiful melody to develop.
The third movement is a triumphant minuet in D major, featuring a more subdued trio written primarily for strings (with a bit of oboe).
The fourth movement, also in D major, is a long dance in 12/8 time cast in sonata-allegro form.