To prove her point, she sprang up to demonstrate the difference between the light, puffy lift-off of Western ballet and the deep-grounded profile of the Indian dance style, Bharata Natyam. It is an eloquent showing. It is made more impressive by knowing that Mrinalini Sarabhai is somewhere around 75 years old.
She is currently in Britain as the jewel in a comprehensive Indian dance season, "Chakra: Cycle of Indian Dance Theatre", at the Bloomsbury Theatre. But she is more than a centrepiece. Mrinalini Sarabhai is a living history lesson. In her 70 years of dance, she has been part of an extraordinary cultural sweep that has seen Indian dance go from disrepute to international status, from margin to mainstream. She has seen the greats of dance, and helped change the face of her country's cultural history. Sitting on a sofa in a borrowed Maida Vale flat, she seems decorous and as poised as a peacock, her moss-green and coral sari carefully arranged and pressed, her antique jewellery glinting. But underneath the restraint lies an unmistakable single-mindedness. Only the blind and foolish would not respect it.
Her utter certainty took her parents - sober folk with not a scrap of the arts in their background - aback. At the age of three, she told them firmly not that she wished to dance, but that she was a dancer. ("I must have started in my previous life.") What were they to do with her? Her father was a lawyer ("very, very brilliant"), her mother was deeply involved in politics, the anti-British movement and the Congress Party. Dance had toppled from its ancient 3,000-year supremacy and was then not de rigueur. Its associations with temple prostitution made it impossible for girls of good families. And there were, unlike today, no dancing schools. Indeed, Anna Pavlova, visiting the country at the time and hoping to see some real Indian dance, was told by her hosts complacently that it had virtually gone.
In fact, it was underground, being carried on by great traditional gurus, who were teaching dynasties of fine temple dancers. Fortunately for Mrinalini, she was born when a few intrepid people were starting to reclaim dance and to brave social disapproval. And so she had her way, learning the sculptural Bharata Natyam style with great masters. Formidable men, she nevertheless was loved by them, despite her habit of arguing. "I used to tell them: 'My body doesn't want to do that.' My body would simply not betray me, something I think one is born with."
It is not hard to see why she won them over. Mrinalini was, as they were, driven. Her quality of focus is unremitting and clear to see even today. She had to dance. "It was," she said, "a compulsion." From the age of 10, she practised 18 hours a day. Later, learning the South's second great dance style, Kathakali, with its deep lunges, powerful martial kicks and, yes, the grinding, incessant plie stance, she began at 4am each day. Dance was a hard, implacable master, insisting that it be put first. There was to be no tennis, no riding, none of the other things she loved. Just dance.
At 16, she had a stroke of luck. Her mother, realising her daughter would never go to college (unlike her brothers, both of whom went to Oxford), enrolled her in Rabindranath Tagore's visionary arts school in Shantiniketan. "With Tagore, I really found my home. He was quite old, but the most attractive man I'd ever met."
Tagore returned the approval and immediately cast her as the lead in his latest dance-drama. But instead of telling her what to do, he gave her licence to create her own choreography, completely reversing the principle of her traditional training. Shantiniketan in the 1930s was a cauldron of change and creativity. It approved of exploring the barriers between the different classical dance forms - the grand austerities of Bharata Natyam could meet the lilting dance from Manipur and the supercharged, traditionally all-male power of Kathakali.
"I loved Kathakali but Bharata Natyam is still my favourite... its strengths and its lines. Why? Kathakali and Manipuri are group dances, but in Bharata Natyam, you're on your own. It's very much an inward dance and that is its strength."
She demonstrated. "The arms have to be like this - with a squareness and yet a curve, and with the palms facing forwards." Straighten the arms and the careful line is lost. "It's very hard. Even now, when I do it, it hurts." And then there is the other side of all the Indian dance styles, the expressive aspect, or abhinaya. "You can teach Kathakali abhinaya because it's all in the muscles of the cheeks and eyes. But Bharata Natyam is all mental, and students find it very difficult. That is why you have to be more mature to do it."
The hours of chipping away at the dance styles and working to perfect the lines of torso, arms and hands were slow and meticulous. But they inevitably brought their rewards. Her reputation slowly spread among the small but growing dance fraternity in India and she was summoned to join the troupe of the great dancer Ram Gopal. It was here that her life changed. A bright young scientist arrived at the studio one day looking for dancers for a workers' theatre. "I never wanted to get married. Nor did my husband. But when I danced for him, he noticed me as a very serious person too, and we started meeting." A year later, they married.
Marriage with Vikram Sarabhai was a double-edged blessing. Since he was a scion of a wealthy mill-owning family, it meant comfort, status and security. He also understood and supported her need to dance. But at the same time, it brought problems. They settled in his family home in Ahmedabad in the more northerly state of Gujarat. Overnight, she found herself amid a new language and a new culture. In many ways, it was a change for the worse. While the South had begun to be sensitised to dance, Gujarat was still locked in old-fashioned hostility. Her natural mode of expression was not in a language that society approved.
Start your own school, her husband urged her, after a time in which she surrounded herself with South Indian dancers and musicians. It was wise advice - it led to the establishment of Darpana in 1948. Today, the school, which has trained over 15,000 students, created over 400 productions and given over 22,000 performances in 45 countries, is part of the region's rapidly increasing cultural profile. "Lots of things I had in my favour. I came from eminent families, so they knew I didn't have to dance. But I worked damn hard." And local society capitulated. "The whole of Gujarat now wants to dance. When boys ask for a bride, they specify she has to dance. And what's more, she must have learnt at Darpana," she says triumphantly.
To any other woman, this would have been enough. Mrinalini Sarabhai, however, has never cared much for boundaries and limitations. Years before the more general development of a contemporary issue-based dance work, she is at pains to point out, she was making work that experimented with both form and subject matter. Discrimination against women stirred her concern back in the Sixties and led to a work that will be performed in the Chakra season by her Darpana company this week.
She is not a maverick, though, unlike some modernists. Mrinalini has managed to steer a complex and skilful path, combining tradition with innovation, shock with reassurance, privilege with protest. Using the diplomatic skills of her politician mother, she laid down a careful blueprint for her early programmes: first some highly virtuoso classical work in Bharata Natyam and Kathakali; and then, once the audience had been awed into silence, came the modern work. In that way, no one could write her off with the common claim that she only danced "modern" because she couldn't handle the rigours of classical dance.
But with the shrewdness has gone an openness and a curiosity that continue, in her 70s, to stand her in good stead, for life is still bringing changes. Increasingly, she has been drawn away from teaching by her dancer daughter Mallika (Draupadi in Peter Brook's Mahabharata). She has toured with Mallika's work for Pan Project, in Australia and now here, and is absorbed in her daughter's own experiments with the form. "Mallika has given me a new lease of life.Young people today are so much more alert. They have much wider vision in the sense of thinking. We had to grope for thought. I know I have made my contribution, but," she adds with a rare edge of ruefulness, "I often wish I could live 100 years more." On her present record, that doesn't seem impossible. And who can swear she wouldn't still be dancing?
n 'Chakra: Cycle of Indian Dance Theatre' at the Bloomsbury Theatre, Gordon St, London WC1 (0171-388 8822) to 4 Nov. Includes: Mallika Sarabhai (Bharata Natyam and Kuchipudi) 7.30pm tonight; Mrinalini Sarabhai lecture 6pm, dance 7.30pm tomorrow