Also, everyone thinks they know Candide - you hear people described as 'Panglossian'. So if Candide appears on a poster, it feels familiar.

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.

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.

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.

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 .

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.

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.