What drew you to the tale of Hardy, the maths professor, and Ramanujan, his self-taught Indian protégé?

G. H. Hardy (played by David Annen) saw mathematicians as pattern-makers, like poets or painters. Credit: J. JAN BOS

I grew up in Cambridge, surrounded by academics' stories of brilliant people, including these two. Then, around 1997 I was in Toronto talking to the writer Michael Ondaatje about creativity — in a bowling alley. He said, “The best book I know about creativity is Hardy's The Mathematician's Apology”, and he gave me a copy.

It haunted me. I started to read about how, in 1913, Hardy got a letter from Ramanujan so interesting that Hardy brought him to study at Cambridge University. The pioneering work they did together meant that the frail Ramanujan was made a fellow of the Royal Society before he returned to Tamil Nadu in India. By 1920 he was dead.

After I had made Mnemonic — our play on the discovery of Ötzi, the 5,000-year-old 'iceman' — the book just kept nagging at me. So I did some research with the mathematician and actress Victoria Gould.

We discovered that this almost mythological story of somebody finding somebody else at the beginning of the twentieth century is important on many levels: for the scientific and mathematical ideas that are still being used; for the image of collaboration; for the notion of misunderstanding or accepting another culture, which is still present.

Composer Nitin Sawhney has created tabla lines based on Ramanujan's work, and mathematician Marcus du Sautoy inducted Complicite into primes and hypergeometric series. Even the president of the Royal Society, Martin Rees, advised. What have you discovered through this collaboration?

I learnt that mathematics is a relay race. This provides an important image of human continuity in these egotistical times. In biology or physics or chemistry, people might have an idea that is then completely refuted, but Euclid's proof of the infinity of primes or Pythagoras's proof of the irrationality of the square-root of 2 are immutable.

Likewise, I am constantly in a relay race. Only when somebody gives me an idea can I transform it into something else. If I sit by myself in an office to write down ideas, they vanish. The moment I'm in contact with other people, they seem to flow.

Hardy felt that a mathematician, like a painter or a poet, is a maker of patterns. A director is also a maker of patterns. Theatre is what the audience makes of those patterns. It is an act of communal imagination, of collaboration. It is no coincidence that theatre audiences are about the size of early human communities. Theatre touches on people's fundamental need to connect.

Like a lab, Complicite creates through years of experiment and iteration. How?

I am completely remaking A Disappearing Number for the Barbican Theatre in London from the show that toured Europe earlier this year. Each time you work at something again, you try to make it a little more accurate, to take it another step further, to make it more compelling, more comprehensible.

There is a great freedom in saying “let's just throw this away”. At the same time, when you discard ideas, you have to be careful not to take away what was instinctive and intuitive. You can be left with something much too simplistic. This brings us back to Ramanujan and Hardy. Ramanujan lived with an enormous amount of mystery and, in mathematical terms, roughness. He was constantly guessing and approximating, nonetheless coming up with extraordinary ideas. Hardy was a great deal more disciplined in the way that he created proofs. In the end, some say the mathematics of Ramanujan is much greater than that of Hardy.

The Elephant Vanishes , your 2003 show, investigated the wave–particle duality of light. In 1999, Mnemonic juggled archaeology and neurochemistry. Might audiences be more afraid of maths than any of these topics?

We're addressing that. The play begins with the explanation of the functional equation of the Riemann zeta function — to do with the distribution of primes — and that is as difficult as it gets. Even if the audience doesn't understand the mathematics, they start to get a sense that it can be beautiful, simply for its elegance and economy. Great ideas themselves are touching, in the same way that a human story is touching.

Hardy was the only person who could recognize how incredible Ramanujan's work was, because he could appreciate something enormously, even if it was plain wrong. The pattern of how or why it was wrong fascinated him — as we might be enchanted by any other work of art.

What idea would you like to play with next?

Consciousness. Theatre must always be interested in what we don't know. We still can't explain consciousness — whatever Daniel Dennett might say. Putting things we don't understand on stage is a process of trying to learn about them: you communicate something of what you're learning, and perhaps take the audience on the journey you are in.