Richard Strauss's incidental music for Moliere's play Le bourgeois gentilhomme has a convoluted history. The project was first proposed to him in 1911 by his frequent librettist Hugo von Hofmannsthal, who wanted to modernize the Baroque comedy about the pretensions of the nouveau riche for director Max Reinhardt to stage. Strauss, then fresh from the success of Der Rosenkavalier and at the height of his creative powers, also agreed to contribute a miniature opera in place of the ballet in Moliere's original. The operatic interlude, like the ballet, would tell a mythological story: in this case, the tangled love between Ariadne and Bacchus. The disappointing premiere of Hofmannsthal's adaptation prompted both composer and librettist to make revisions, and first to go was the opera, whose presence had confused audiences. It was spun off and elaborated into a full-fledged opera titled Ariadne auf Naxos, one of Strauss's best. After some tinkering Strauss considered junking the rest of the music but at Hofmannsthal's urging thought better of it, and in 1918 the three-act play Der Burger als Edelmann was presented to the public with a witty, enchanting, Mozartean score. The rather loose adaptation, with English translation by Richard Wilbur, is rarely performed in its entirety, but it will be in this concert version by the Ravinia Festival Orchestra and guests. Conducting the orchestra, a pickup outfit including many Chicago Symphony Orchestra players, is Franz-Paul Decker, a veteran of the Canadian and European Symphony circuits making his Ravinia debut. The three soloists--soprano Kimberly Jones, mezzo-soprano Eleni Matos, and baritone Elias Mokole--are top-flight talents from Lyric Opera's Center for American Artists. Handling the narration duties will be Werner Klemperer, whom you might remember from Hogan's Heroes. Also on the program: Mozart's Symphony no. 29. Thursday, August 26, 8 PM, Murray Theatre, Ravinia Festival, Green Bay and Lake Cook Rds., Highland Park; 728-4642.