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

Optimism and happiness are not the same thing, but they are becoming interchangeable, and it seemed to me that Voltaire's Candide gave me a way into something important happening in modern-day culture.

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 .

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

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

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

Twenty years ago, when you bumped into someone and asked how they were, they would say, 'Mustn't grumble' or 'Getting by': now they feel obliged to say 'Just great!'. In both cases, the reply is just a social nicety, but the framework has changed, it's as if it's become a social duty to express happiness.