I have adapted the whole book [Candid] into tweets of 140 characters, and these are being sent out daily, at the rate of eight tweets per day .

Candide is one of those books I read when I was young and that I come back to regularly.

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.

We are now so far advanced in our denial of evil that we want to rationalise it away.

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.

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.

Translating Candide into tweets has really deepened my appreciation of his writing - it wouldn't work so well with nineteenth-century authors. Every single sentence in Voltaire seems to advance the story, and yet stand alone as a sound-bite.