Juliette Binoche: My step into the unknown

The actress Juliette Binoche reveals why she's turned to dance, what it's like to work with Akram Khan, and how much she misses Anthony Minghella

So why should I start dancing? I never really asked myself that question. I always felt, anyway, that I was dancing. To act is to dance. Isadora Duncan is an important artist for me. I read everything I could about her when I was playing Nina in Chekhov's The Seagull a very long time ago, when I was 21 in France. Isadora had Sarah Bernhardt as an icon, and this feeling infected me, too, so I was very Isadora when I played in Konstantin's over-heated play-within-a-play.

My work on this new theatre piece with Akram Khan, in-i at the National Theatre, which then goes on a big international tour, is nothing to do with trying to force a new stage in my career. With Akram, I felt that we could confront and share new desires, hopes and visions through our respective arts by inventing a common language. I don't know the result yet, but I know the path that we're taking is changing me radically. I never know what I'm capable of before I do it.

I may not have danced all that much before, but I'm aware of my body through doing Pilates. I'm 44 now, and I have two growing children, so I try to keep my energy levels as high as possible. With this new theatre piece, I know where we're going when we enter the theatre, and it's nothing to do with being a work in progress – everything is a work in progress. I'm changing all the time.

How can I say what my new performance will be about? It's impossible, and there can be no diagnosis until the audience takes what they get, the medicine on the spoon. I don't think that "show" is the right word. It is, I hope, an experience. I really don't see art as being an expression of something outside of myself. Whether it's writing, or painting, or dancing – which I have never done before on a stage – the medium changes because of what it is you are trying to express.

I secretly hope that faith will take over. I don't want to be an actress, as a point of principle, why should I? It just happens that I'm acting because I'm in the process of meeting someone, myself, on the way back. But if you told me tomorrow that I wouldn't be acting any more, then I'd be fine with that. Art is not about hanging on to things – it's all about inventing.

It is the same thing whether I'm painting or acting. The common denominator is in the movement. I don't dance but I paint in the air. Or I don't paint, but I dance on the paper. My portraits of directors that are on show in the BFI alongside my film retrospective are impressions of people I've worked with at moments of reflection, or crisis, or creativity. And the portraits of myself are critical, and I think – I hope – revealing.

It's very strange to be here in London without Anthony Minghella, whom I loved very much, and very painful. I was so frightened in the first week of shooting The English Patient, I was trembling, but he was trying to find a way to win my trust, and he just said to me, "Well, fly..." and I did and it changed my life. The poems that I've written in both French and English – they just came as they came, in French or English – complement my portraits, and the one for Anthony is very special to me:

searching in the battle of being

we attempted to glimpse the other side

dance took us in its arms

bliss of green nature in the land of oil and vine

your ideas became real to me

jumping to the hopscotch in the night

ascending to the paintings of your imagination

I grew by leaps and bounds

oil perfume mingled with hair

we traced our lives

your call came with silence

I was your angel as you opened my wings

I would jump forever

in the most sacred place

yearning for the sensation of trust

of love beyond ourselves

you taught me to be more human

lifted like a gift to myself

feet arms heads and hearts

we walked together as if life was happening

somewhere else

with joy with joy

I hope that conveys something of his talent as a human being, let alone as a film director. The two things are the same in my book. And that's what the show is about, perhaps – it's not about the answers, but the questions. Do we dare to love? Is emotion really love? I don't register any difference in my relationship with Akram as a person or as an artist. We discover things about each other as we do it. I didn't know him well to start with... we were diving off a high board without knowing where the water was.

But now we know each other really well. We have been through a lot of improvisation, starting with emotion and what emotion can do to the body, and that creates the movement. It's a question of unlocking that emotion within ourselves and seeing how it moves, how it is animated. It was the same process, really, when I played in Pirandello's Naked directed by Jonathan Kent at the Almeida 10 years ago and later in Pinter's Betrayal, directed by David Leveaux, in New York.

It's not a question of my being desperate to get back on to the stage. Even on a film set there are lots of people watching you. It's the same kind of involvement; it's just moving from an intimate to a more exposed space in the theatre. But the terror is the same.

Juliette Binoche was talking to Michael Coveney. 'in-i' will be at the National Theatre, London SE1 (020-7452 3000), from 6 September to 20 October; 'Jubilations', the retrospective of Juliette Binoche's 25-year film career and an exhibition of her paintings, takes place at BFI Southbank, London SE1 (020-7928 2525) to 15 October; Binoche's poems are published by Culturesfrance