Mozart loved the theater in every form, but wrote incidental music for only one play. The distinguished playwright Baron Tobias Philipp von Gebler asked Mozart to write music for performances of his five-act drama Thamos, König in Ägypten in Vienna in April 1774. This was to replace other music that did not please the Baron, and Mozart apparently was able to complete only two choruses for those performances. When the play was given in Salzburg in January 1776, Mozart added orchestral interludes. He revised this music yet again in 1779, for performances in Salzburg by Johann Heinrich Böhm’s company. None of this gave the play any enduring popularity, and Mozart later allowed Böhm to reuse some of the music in another play.

Gebler’s play is a Masonic allegory, and though not yet a Mason himself, Mozart gave it much of the expressive symbolism he later lavished on The Magic Flute. This is particularly apparent in the first Interlude, with its richly rhetorical chords, slippery chromaticism, muscular tension, and its contrast of light and dark.

The woodwinds and horns come to the foreground in the second Interlude, with muted violins. In the autograph score, Leopold Mozart indicated that the early little transition with the off-beat bassoons and sudden shift from E-flat major to E-flat minor represented the falsity of the traitor prince Pheron, and that the immediately following forthright oboe tune in B-flat portrayed the honesty of King Thamos.

Act IV ends in great confusion, and the ensuing Interlude begins off kilter, in turbulent D minor with fierce accents on the fourth beat in each measure. The brilliantly scored movement is one of motivic bustle and dynamic rhythmic verve. It switches to triumphant D major, ending with one of those “Mannheim rocket” crescendos Mozart favored at the time and the same big offbeat chords as the opening bars.

John Henken is Director of Publications for the Los Angeles Philharmonic Association.