The Vienna Philharmonic is a workhorse, occupying both the opera pit and the concert stage. This is true in Salzburg during the summer, and in Vienna during the regular season. James Brown bills himself as “the hardest-working man in show business.” The Vienna Philharmonic may be the hardestworking orchestra in classical music.

Here at the Festival, the orchestra is playing a slew of Mozart operas — there are no one else’s operas this year — under a variety of conductors.And, every few days they take the concert stage for a program of nonoperatic music. This is what they did Tuesday morning (11 o’ clock). Their conductor was Riccardo Muti, who is also leading them in “The Magic Flute.”

The program began with — guess who? — Mozart, of course, specifically his Concerto for Two Pianos in E flat, K.365. At the keyboards were Saleem Abboud Ashkar and Itamar Golan. Now, why would the Salzburg Festival invite virtually unknown pianists, when even celebrated pianists fail to receive an invitation?

A glance at the program booklet made the answer clear: Mr. Ashkar is a “Palestinian,” according to his bio. (He might also be described, I suppose, as an Israeli from Nazareth.) And Mr. Golan is a Lithuanian-born Israeli.

Both pianists played competently, showing some gracefulness and overall style.Their passagework was sometimes not together. But this is often true of a single pianist, working with two hands. We must be lenient when judging the passagework between two pianists, employing four hands!

The second movement of K. 365 is an Andante, and here Maestro Muti was a bit leaden, not achieving a Mozartean, Andante flow. Mr. Ashkar, however, was particularly fine, demonstrating smart rubato (or license with tempo). As for the closing Rondeau, I will use a statement I applied to a Maurizio Pollini performance in a review yesterday: It had a decent zest.

The duo-piano performance was nothing like excellent, but the audience in the Great Festival Hall cheered for Messrs. Ashkar and Golan like they would have for Backhaus at his height. I cannot believe that the reason was musical.

The concert continued with a new work, written by Fabio Vacchi. Who’s he? A Bologna-born composer in his mid-50s. According to Max Nyffeler’s program notes, Mr. Vacchi is “one of the most performed internationally of Italian composers of his generation.” I’m not sure that’s a significant boast.

Mr. Nyffeler further informs us that Mr. Vacchi’s music “demands an alert, attentive listener who is ready to abandon himself to it — and be richly rewarded in return.”Well, if you say so. Moreover, we learn that Mr. Vacchi is a political chap, eager to put music to social and political ends. A word of advice: When you hear that about a composer, watch out.

Mr. Vacchi’s new piece is called “La Giusta Armonia,” or “Just Harmony” (“Just” meaning “Right” or “Righteous”). It uses a text by Franz Heinrich Ziegenhagen, whom Mozart knew. In fact, Mozart used this text — a manifesto — for one of his Masonic cantatas. According to Mr. Nyffeler, Ziegenhagen was “a Pietist and utopian socialist.” And, whereas Mozart treated religious aspects of the text, Mr. Vacchi has taken up “social aspects: the imbalance between rich and poor and the senselessness of excessive property that is an obstacle to man’s happiness and a cause of war.” Etc.

As you might expect from a piece of music that wants to preach to you, “La Giusta Armonia” uses a speaker, and this role was filled by the Austrian actor Peter Simonischek. (He looks a little like Kris Kristofferson.) Mr. Simonischek preached, or orated, ably. But as he did so, I felt a chill, for I was reminded of the horror of political demagoguery. I don’t think Mr. Vacchi intended this effect.He wants to be anti-tyranny; but his piece is so bullying, it might be regarded as slightly tyrannical itself.

Put it this way: If Mr. Simonischek had been on a balcony, he could have been Mussolini.

This was a special pity, because, from a strictly musical point of view,”La Giusta Armonia” is not negligible. And Mr. Muti conducted it keenly.

The program closed with another piece by Mozart, and one of his most frequently performed (and one of his greatest). How many times have you heard the “Jupiter” Symphony in this Mozart anniversary year? Here’s a related question: How many times have the current members of the Vienna Philharmonic played it? Last summer, one of the concertmasters, Werner Hink, said in an interview that he had played “The Marriage of Figaro” over 500 times — and could never tire of it. The same is probably true of the “Jupiter,” for such musicians.

And the Philharmonic played it very well Tuesday morning (afternoon, by this time). Mr. Muti was near the top of his game — allowing the piece to breathe, but maintaining discipline. He wasn’t at all leaden in the Andante, but fresh and singing. (Actually, the full marking is Andante cantabile, or a singing andante.) What was disappointing, however, was the finale, that unparalleled outpouring. It was oddly restrained, without its due robustness and joy.

Still, Mozart triumphed again, even if no one else did.

Salzburg Festival until August 31 (for more information, call 011-43-662-8045-500).