Music review: Gustavo Dudamel conducts Mahler's Third Why Mahler? That's the question in the title of British critic, commentator and classical music gadfly Norman Lebrecht's feistily engaging new book that considers Mahler not just as a composer but a cultural force relevant to our multicultural age. Lebrecht is this week's Mahler scholar for the Los Angeles Philharmonic's Mahler Project. In his packed Upbeat Live talk Tuesday night at Walt Disney Concert Hall, he described Mahler as the first composer to use the symphony as a medium for social protest. Gustavo Dudamel followed that talk with Mahler's sprawling Symphony No. The orchestra was the Simón Bolívar Symphony Orchestra of Venezuela, which is sharing the Mahler Project with the L.A. Phil. The brawny Bolívars were, as they had been two nights earlier in an overpowering Mahler Second, a sonic force to be reckoned with. Their ensemble was, this time though, a bit messier. The Mahler Project -- which began on Jan. 13 but will be really heating up this week and next with six of the nine symphonies -- is going to have its ups and downs. But the Bolívars also happen to be a noted social and cultural force to be reckoned with. An impossibly large orchestra of some 175 young Venezuelan players, many of whom came from economically disadvantaged backgrounds, grappling with the demands of the longest symphony in the standard repertory (Dudamel's timing was 102 minutes) is its own kind of social and cultural statement. Issues of individual and society are paramount in Mahler. In the Third, Mahler spread his net of questions -- his whys -- broadly. He said the symphony was to stand above worldly struggles and cast the work as a summer's midday dream. The season marches in, then in succeeding movements, Mahler quizzes the flowers, the animals in the forest, man and the angels. In an enthrallingly lyrical, long, final slow movement, he reveals what love tells him. That's some summer nap. The symphony opens with a big melody that Mahler set for eight horns, refashioning a buoyant symbol of German nationalism (Brahms used the tune to triumphantly end his First Symphony) in the minor. In his talk, Lebrecht intriguingly interpreted the context as Mahler, a Jew forced to convert to Catholicism in order to be hired by the Vienna State Opera, presenting a warning to history. Mahler's is the voice of the striving minorities in a monolithic society. The Bolívars had a dozen horns blaring that opening march of summer optimistically, almost like a battle cry. And throughout the performance there were any number of instances when the individual took a stand. Solo passages could be showy. The winds were notably aggressive and the brass blew everyone away. In the third movement, an offstage fluegelhorn imitates an old posthorn or valveless coach horn in a melancholy solo. Heard floating off in the distance, it is one of the supreme nostalgic moments in Mahler. The Bolívar player was bold; his was more a reminiscence of Miles Davis and Maynard Ferguson. Dudamel's approach was to supply as much character as he could get away with, and occasionally a bit more. The second movement is a minuet, with Mahler's instruction for a very moderate tempo. But the lilt of the dance was immoderate gaiety. The fourth movement is dark; it sets a text from Nietzsche for mezzo-soprano, which was robustly sung by Christianne Stotijn against intense strings. The fifth movement is light. Bells ring. Children (the Los Angeles Children's Chorus) and women (from the Master Chorale) are the voices of angels. It was triumphant. In the final movement Dudamel went for big-boned rapture. The orchestra was tired and intonation was off. But there was a sense of striving and a sumptuousness of sound that grew bigger and bigger and finally huge. The Bolívars don't have the experience with the Mahler Third that they have with the Second or the Fifth (the latter of which they will play Thursday). But this performance revealed just how much excursion is required for an exceptionally large ensemble of young musicians to master Mahler the way they had with the Second on Sunday. And that alone is an inspiring manifestation of the struggle of a society coming together for a common goal. Photo: The Simón Bolívar Symphony Orchestra of Venezuela at Walt Disney Concert Hall Sunday night.