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.

Even within single sentences, there are sudden changes of register. And when the travellers go to Venice, they see a play by Voltaire! This is a novel [Candid] which has narratives within narratives, such as when Cunégonde recounts her story.

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.

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 .

It's a book that makes me laugh and think - it would be very hard to like someone who didn't enjoy Candide!

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

In the business world, the idea of positive thinking is absolutely entrenched.