Pina Bausch, Sadler's Wells, London

Sometime in 1978 a bunch of earnest undergraduates stood huddled in a drama studio and struck an unusual deal with their tutor. The deal was to keep mum about what went on in that locked room during the next two hours. In exchange, the students were promised a taste of some of the most exciting developments in European theatre. Twenty-five years is a long time to keep a secret, but it's taken me the best part of that time to realise that the unclothed humiliation/domination games we played that day - and for the record, our tutor was scrupulous in the way he conducted them - were crudely inspired by the experiments Pina Bausch was conducting in Germany with her then-young company Tanztheater Wuppertal.

Sometime in 1978 a bunch of earnest undergraduates stood huddled in a drama studio and struck an unusual deal with their tutor. The deal was to keep mum about what went on in that locked room during the next two hours. In exchange, the students were promised a taste of some of the most exciting developments in European theatre. Twenty-five years is a long time to keep a secret, but it's taken me the best part of that time to realise that the unclothed humiliation/domination games we played that day - and for the record, our tutor was scrupulous in the way he conducted them - were crudely inspired by the experiments Pina Bausch was conducting in Germany with her then-young company Tanztheater Wuppertal.

Today Bausch is a world brand, her ideas endlessly mimicked and referenced and theorised, and the core performers of her redoubtable troupe are well into their fifties. Yet a work like Nelken (1982) or Palermo Palermo (1989) can still send audiences reeling and floundering in their primal soup of behavioural observation. No one can see Bausch's work and emerge indifferent, and people love or loathe her pieces for identical reasons: their rambling structure, the apparent randomness of events, the infrequency of anything resembling dance, the stiltedness of the spoken text, and the way Bausch inexorably homes in on secret pain and cruelty. Above all, it incenses some, thrills others, to encounter an artist of iconic stature who so implacably refuses to explain.

These same qualities also make a standard review seem pretty pointless, since each successive image or incident - and there can be hundreds of them - will resonate differently for every viewer. Yet a bigger picture does emerge, accruing gradually like pointillist dots, each partially obliterating the last.

And every work starts with a sensation. In Nelken the stage is carpeted with 8,000 artificial carnations, each perfectly set on a long green stalk, innocent and pink and virginally crinkled like the skin under a baby's foot. It's a ravishing sight, yet even before the arrival of the 21 dancers, quartet of stuntmen or team of Alsatian dogs, you're braced for the degradation. At first the performers pick their way gingerly through the stems, careful not to crush them, but soon the scene is scarred like a battlefield. It's what happens to our lives, our growing consciousness. And didn't Bausch grow up in 1940s Germany, a time when the word conscience dropped out of the language? Pop records of the period crackle messages of nostalgia, but when a lugubrious man in a suit spells out the lyrics of Gershwin's "The Man I Love" in sign language, the sentiment is empty and absurd. Well-dressed couples sit on chairs listening to light classical music and wearing smug expressions. The same men then reappear in girls' frocks and play at being rabbits, surveyed by narrow-eyed guards with dogs. Even post-Grayson Perry, the Turner Prize girlie, infantilism combined with cross-dressing leaves us with a deep unease. Is it that we disparage the urge to regress? Or that we dare not re-learn the freedoms of childhood? One of the bunny men is commanded to show his passport. After examining it, the man in the suit concedes: "You may continue to hop." Such humorous reprieves in Bausch, however brief, are always welcome.

Images of childhood rub up hard against images of domination. On one level, it's the authority of the parent forcing the kid to eat up her peas; on another, it's the intimidation of a queue of mature males terrifying a woman by repeatedly flinging themselves off a table. They don't lay a finger on her, but it's rape by another name. Extravagant stage pictures emerge, long lines of bodies rocking mesmerically back and forth on chairs while others frantically assemble cardboard buildings onto which sinister-suited men crash suicidally from a scaffold. Such scenes have the crazy disjointedness of dreams, yet what's distilled is like the moment of waking: something unsayable becomes clear.

If Nelken is about humiliation and stolen personal power, Palermo Palermo is about people trapped in the social tropes of culture and religion. It's a world of collapsing walls, of heat and dust and detritus, a world of mothers and whores, husbands and sons caught in the roles they are allotted. Again, there's cross-dressing - worse, the Virgin Mary intrudes - again the women storm about in perilous heels. A boxer in elaborate drag slices raw steak from his own wrist, fries it on the back of a hot iron and gobbles it up - not cannibalism, surely, so much as a comment on transubstantiation, core tenet of Catholic belief. A radiant and proud young man is confronted by a crabbed old woman who pisses at him from a mineral water bottle held between her knees. What does it mean? That the mother sacrificed her youthful body to create life? That the matriarch scorns male achievement? Bausch doesn't intend there to be a single answer. She demands merely that we open ourselves to our own responses, surrender to the energies of her charismatic performers, and trust her stagecraft to deliver. For me it delivers magnificently.

jenny.gilbert@independent.co.uk

'Palermo Palermo': Sadler's Wells, London EC1 (0870 737 7737), tonight at 6pm, returns only