There is the question of language. Although the play [Candid] is not written in strict verse form, there is an underlying beat of rhyming couplets, with echoes of Pope and the tradition of eighteenth-century philosophical verse.

The title's so upfront. It gives fair warning about the play's content. I'm writing about a kind of disenchantment, an anger, but quite a cool 90's anger, at a time when we're not very good at openly being angry. . . . I don't think I ever thought the title was titillating. I thought it was incredibly catchy. If the play is about the reduction in human relations down to a consumerist rationale, then thematically, the title is entirely linked into the thesis of the play.

There is a remarkable nimbleness of style, a balancing act of tone, in Voltaire, which is hard to bring off on stage. When you speak the words out loud, the effect is very different from when you read them. So one needs to do something new with a stage performance, not simply 'tell the story'.

Rereading Candide, I was struck by the link between optimism and the optimal, the idea that we have been placed in this optimal world rather than some other.

Voltaire's novel [Candid] offers us parallel universes, the possibility of entering into alternative worlds existing side by side, and this is something quite modern. Nested narratives and parallel universes are popular at the moment in many different art forms.

The financial crisis happened because no-one could actually say out loud how bad things were.

The American journalist Barbara Ehrenreich has written about this in her book Smile or Die: How Positive Thinking Fooled America and the World (2009) . She talks about the happiness industry, the rise of medication to make us happy and of self-help books, and the influence of all this on religion. In many ways religion has become another form of self-help. We all suffer from over-exposure to positive thinking.