Ironically, though Daniel Barenboim's Proms series features Beethoven, its greatest achievement long term may be bringing Boulez to mainstream audiences. Barenboim is a man of courage and principle. He's confronted social injustice, and now he's challenging musical prejudice.

Although the singer (Hilary Summers) sings in only four of the nine sequences of Boulez's Le marteau sans maître , it is a work infused with the concept of voice, a kind of meta-song. "Whereas Pierrot Lunaire is a theatre piece with instrumental accompaniment, the voice always prepondering," said Boulez in a description of the piece. "Le marteau sans maître stems from the cell of a poem which is eventually absorbed in toto". As a young man, Boulez was drawn to the poetry of René Char and wrote three major cycles based on his work. "Le marteau sans maître is thus crucial to any understanding of Boulez's output.

Char was a surrealist In his poetry, images are compressed, as if by homeopathic distillation. The poet's brief phrases don't reveal meaning in the usual sense, but force the reader to respond intuitiuvely. "Sudddenly", said Boulez, "You recognize yourself.... the illuminating paragraph seems simultaneously to take possession of you, and to increase your potential, your grasp and your power beyond anything you had dreamed possible".

In Le marteau sans maître, Char's words are crystalized still further so their very relationship with obvious meaning dissolves into the music itself, like a droplet spreading concentric cirles in a pool of water. Words are used for musical quality, such as alliteration. Boulez specifies that the singer is not a soloist. She sits with the ensemble, so the flow between players is uninterrupted. At the end, she intones abstract sound, almost the sound of body rhythms, and the flute (Guy Eshed) sings on her behalf, as had the viola (Ori Kam) before It's significant that Char was anti-fascist long before the German occupation. On a very deep level, Boulez is reiterating Char's beliefs in the value of the individual against the mass. He uses a strict, almost mathematical structure of three internal cycles within the nine pieces and other more subtle interrelationships. From this almost ritual formality, however, springs freedom of invention. Hence, the concept of hammer without a master.

Yet how that "hammer" is wielded ! Instead of blasts of massed brass and percussion, the "aural violence" of the orchestral palette, Boulez uses a small ensemble, where instruments are carefully balanced in terms of pitch and timbre. Lines are short, with lively traceries of individual notes rather than full tutti. Nor does he demand Lachenmann-esque distortions. These players aren't there to show off, but to co-operate. Boulez also emplys instruments that suggest, but don't copy, instruments from non-western cultures. The guitar (Caroline Delume), suggesting the Japanese koto, xylomarimba (Adrian Salloum) and vibraphone (Pedro Manuel Torrejon Gonzales) suggesting gamelan and the African balafon. They exist, not as exotics, because they can express the non-dogmatic nature of the piece and its sparkling fragments, merrily moving together. Even the percussion (Noya Schleien) employs no heavy timpani but a brushes, a gong, maracas, bongos. On this occasion I was struck by how Le marteau sans maître picks up on Messiaen's concepts. In a dawn chorus, many birds sing, but each is individual, and an astute listener can pick them out. In many ways Le marteau sans maître is also a precursor of Messiaen's Sept Haïkaï.

By choosing to showcase Le marteau sans maître in this Proms series, Barenboim is again making an extra-musical statement. This piece gives the musicians much more room to engage than the more complex Dérive 2 at the start of the series and it much more suited to their strengths. Performance is a journey not an end in itself, as a deep reading of this piece might suggest. François-Xavier Roth is a charismatic, slightly eccentric personality (in the best creative sense). He's sensitive to Boulez's idiom, and his rapport with the players was good. In Le marteau sans maître, everyone's a player if they're listening.

Anne Ozorio