My highest compliment is when someone comes up to me to say, "My 14-year-old daughter, or my 12-year-old son read your book and loved it." I cannot conceive of a greater compliment than that - to write something that as an adult I find satisfying, but also that manages to reach a curious 13- or 14-year-old.

We prematurely write off people as failures. We are too much in awe of those who succeed and far too dismissive of those who fail.

As human beings, we always expect everyday change to happen slowly and steadily, and for there to be some relationship between cause and effect.

Re-reading is much underrated. I've read The Spy Who Came in from the Cold once every five years since I was 15. I only started to understand it the third time.

It is those who are successful, in other words, who are most likely to be given the kinds of special opportunities that lead to further success.

Six degrees of separation doesn't mean that everyone is linked to everyone else in just six steps. It means that a very small number of people are linked to everyone else in a few steps, and the rest of us are linked to the world through those special few.

That is the paradox of the epidemic: that in order to create one contagious movement, you often have to create many small movements first.