Edinburgh Festival; PINA BAUSCH, Playhouse

The stage is covered with carnations (Nelken), which give the piece its title. Richard Tauber reminds us "how beautiful the world is"; several smiling dancers leave the stage and take individual members of the audience outside, briefly. A woman playing her mother, and herself as a child, alternately shouts and cries. A man in black tie holds out a microphone to relay her trauma and to amplify her heartbeats - "reality" becomes art, as her heart measures out a rhythm made for dancing. A dancer in a three-piece suit recites Ira Gershwin's lyrics to "The Man I Love". Then George Gershwin's music sounds and Lutz Forster signs the words, his eloquent hand-movements filled with grace.

The synaesthetic impact is overwhelmingly strong. It demonstrates in microcosm how gesture can enhance meaning. Male dancers, vulnerable in silk dresses that do not meet at the back, bound across the stage on all fours, like blithe, demented rabbits. Handlers bring alsatian dogs to the four corners of the stage and the man in black tie pursues the aerial creatures. He stops each one, asking, "Passport, please."

Pina Bausch has been so influential that this piece is, in a sense, historic. In the 13 years since Nelken was first performed, it has helped to change the language of theatre and of dance. The work of such epigones as Robert Wilson, Peter Sellars and William Forsythe has reached us first. What is clear is just how risky and ambitious is Pina Bausch's pioneering use of this language. Some of these risks are physical. While the dancers engage frantically in passion-filled movements that suggest an act of prayer, and seem born out of the music - a fragment from Schubert's "Death and the Maiden" quartet - men in black suits cramp their space by assembling mountains of brown cardboard boxes at the edge of the stage. These they tie together with tape. They then wheel on huge scaffolding towers and plunge from their tops into the boxes. The same stuntmen perform dramatic death falls on to a table top, which they gradually bring forward from the depths of the stage to the front, where an observer, their audience, watches, horrified. Eventually, they "die" in her lap.

Other risks are moral: Pina Bausch explores that dangerous area of dance where a well-drilled, uniform, choral movement evokes awe mixed with repulsion as individuals are submerged in mass mechanical movement, so thrilling to see, whether at La Bayadere or at a mass march. By the end, when the dancers walk across the stage, performing simple hand-movements that evoke the passage of the four seasons, we seem to have seen hell as well as heaven. The dancers wear wicked, puckish smiles as a reward for survival.

Thirteen years ago I saw Nelken when it was new. Then Jan Minarik, one of the dancers, took me outside, to the bleak portal of the theatre in Wuppertal where the company is based. "Isn't the world beautiful," he said. It was. Now, 13 years later, I'm struck by how poignant Nelken seems: Dominique Mercy now executes his balletic steps with heroic extravagance; Lutz Forster's cheekbones are still more sharply etched, his smile more sad. But the carnations? They're as beautiful as ever.