Classical music: Maxim Vengerov, LSO / Mstislav Rostropovich Barbican Centre, London

"We need brave music. I mean brave because it is truthful. Music in which the composer expresses his thoughts truthfully, and does it in such a way that the greatest possible number of decent citizens in this country and other countries will recognise and accept that music, thereby understanding his country and people. That is the meaning of composing music as I see it." Shostakovich, quoted in Solomon Volkov's Testimony.

In a pair of Barbican concerts last Thursday and Sunday, the London Symphony Orchestra, with Mstislav Rostropovich conducting, amply demonstrated Shostakovich's notion of truth. In the first, two of that composer's lesser known works left a large audience transfixed. In the second, truth was shown to be brave in a riveting reading of Tchaikovsky's Symphony No 4, although less brave in the public and private faces of Prokofiev as revealed in his Meeting of the Volga and the Don and Violin Concerto No 2. But truth is not only to be found in the integrity of the composition.

Dominating both concerts was the presence of Maxim Vengerov. It's seldom that a London audience rises to its feet, particularly after a work as bleak and introspective as Shostakovich's Second Violin Concerto, but that's what happened at Thursday's performance by this young Russian violinist. Vengerov's recording with the LSO and Rostropovich of the first concertos of Shostakovich and Prokofiev won the 1995 Gramophone Awards for "best concerto recording" and "record of the year". An attempt is now being made to repeat that achievement with the same team recording the two composers' No 2s, and each was given a concert airing last week (the Shostakovich on Thursday, the Prokofiev on Sunday).

Shostakovich wrote his Second Concerto in 1967 but it has never achieved the recognition accorded the First, written 20 years earlier in the teeth of Stalinist repression. The beauty of the Second Concerto is much more elusive but, in a fine performance of such searing intensity as Vengerov delivered, a complete reassessment of this deeply introspective work is demanded.

This young player is extraordinary. It's as if Heifetz, crossed with Grumiaux, has revisited a mere 22-year-old, so sure is the technique, mature the conception and ravishing the sound. How can such a young man project such unutterable despair?

In Prokofiev's Second, the simplicity of Vengerov's opening solo said it all. This concerto may lack the emotional depth of the Shostakovich but Vengerov captures its changes of mood with a sweetness of tone or a skittish ferocity that almost breathes more life into it than may be there. His unegotistical and sensitive chamber music response to his solo orchestral colleagues is awesome. But all this owes much to the rare chemistry of the relationship between soloist, conductor and orchestra. Rostropovich may not be a great technical conductor, but musically the LSO responds to him in grand measure.

Shostakovich's massive Symphony No 11 and Tchaikovsky's Symphony No 4 received devastating performances, while Prokofiev remained neatly and tidily contained. But both nights belonged to Vengerov.