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

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.

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.

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.

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'.

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.

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.