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.

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

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.

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.

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.

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 .

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.