One thing was proved by Friday's Prom. Pierre Boulez will never get to the heart of Janácek. His conducting and temperament are too clinical. He's too wrapped up in making everything crystal-clear. Normally that's an admirable quality. With Janácek, however, the notes make no sense without the passion.

That was a pity, because the BBC Symphony Orchestra (hugely brass- augmented for the Sinfonietta) and the giant choir assembled for the Glagolitic Mass (BBC Symphony Chorus and London Symphony Chorus) both sounded magnificent. So did Simon Preston, thundering out the Mass's spine-shuddering organ interlude. There was musicological interest, too. The Mass was performed in its wild, rhythmically fiendish original version; Boulez is probably one of the few conductors with the technique, intellect and patience to sort out the polymetric complexities.

It was preceded by a rare performance of the Capriccio for pianist's left hand, brass and flute. What an odd little work it is, too: rhapsodic in places, then lurching into lugubrious park-bandstand reminiscences. Jean-Efflam Bavouzet brought an eloquent four fingers and thumb to his singular task.

No shortage of passion the previous night, when Daniel Barenboim and his West-Eastern Divan Orchestra played to a packed Albert Hall. “Usually when we come to the Proms,” Barenboim said at the end, “I am encouraged to say what's wrong with the Middle East. But you've just heard what's right with the Middle East.” The roar of approval that greeted those words said everything.

This Prom emphatically reminded us that Barenboim has not only brought young Israelis and Arabs together, but melded them into a wonderfully responsive instrument. That was made clear in a transfixing performance of Brahms's Fourth Symphony. At first, I was worried that Barenboim's enthusiasm for the “long line” would smooth away too many angularities. Not so. The opening movement and Scherzo had a Beethovenian sense of drama. There was heart-stopping beauty in the slow movement's wind solos and everywhere a masterly elasticity in the phrasing. This was music-making by people who know the meaning of turbulence - and, consequently, the value of serenity.

Introducing the sumptuously played encore, Wagner's Meistersinger Overture, the conductor quipped that he loved putting Brahms and Wagner together with Schoenberg (his Variations for Orchestra was also in the concert), because it was instructive to see how Schoenberg “made a synthesis out of two people who hated each other”. Barenboim must have reflected that he has pulled off much the same sort of miracle.

Hear Pierre Boulez talk about Janácek, his memories of the Proms and his hopes for the future of concert life on our Proms podcast: timesonline.co.uk/proms

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