Trying to prove you’re not a psychopath is even harder than trying to prove you’re not mentally ill,’ said Tony.

It is an awful lot harder, Tony told me, to convince people you're sane than it is to convince them you're crazy.

You can say anything to David Icke and he will accept it and put it into his ideology.

We're living in post-nuance online times.

Suddenly, madness was everywhere, and I was determined to learn about the impact it had on the way society evolves. I've always believed society to be a fundamentally rational thing, but what if it isn't? What if it is built on insanity?

When I asked Robert Spitzer about the possibility that he'd inadvertently created a world in which ordinary behaviours were being labelled mental disorders, he fell silent. I waited for him to answer. But the silence lasted three minutes. Finally he said, 'I don't know.

Obviously, I like to write stories that are page-turners. But I always try my very, very hardest to be as factually true as possible.