Handel's Alexander's Feast and Henze's Voices were both written in the belief that music is a radical force with the power to change people's lives, and to hear them consecutively is to be reminded just how uncannily each illuminates the other.

Handel's setting of Dryden envisions the guests at one of Alexander the Great's victory banquets being moved to desire, grief and bellicosity in turn by the singing of a court musician. Henze's explosive song cycle, composed at the end of the Vietnam war, rages at the atrocities of contemporary imperialism, to which revolution seems the only response. Both works, however, eventually reach an ambiguous close. Henze dissolves political urgency into a love duet of Monteverdian beauty. Handel demands that we turn away from music's pagan glamour and consider it a reflection of the divine. Yet the score turns staid at this point, as if religious safety necessitated a fundamental loss of vision.

Andrew Manze and the English Concert performed Alexander's Feast in the edition Mozart prepared for a Vienna performance in 1790 - a controversial choice, though Manze makes a forceful case for the sensuousness of Mozart's reorchestrations and the heightened sense of drama that ensues. The choral singing, by turns exultant and reflective, was thrilling in its precision. Tenor Paul Agnew was not quite at his best, though soprano Sally Matthews was astonishing: at once angel and seductress, she embodied the ambivalent vision of music at the work's heart.

Voices, meanwhile, was given a blistering performance by the London Sinfonietta under Oliver Knussen. Christopher Gillett was the elegant tenor soloist, Mary King the formidable alto, traversing a vast range of personae from cabaret diseuse to iconic diva. Time has dented Henze's Marxist certainties a bit, and the piece itself now seems over-long, though the best of it is electrifying.

· The Proms continue until September 9. Box office: 020-7589 8212.

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