Children are bought and sold like animals, sometimes at a lower price than animals. 168 million children work as child labourers, more than 200 million children who should be in education are not at school.

I often describe a Grand Slam as a marathon, not a sprint. It involves enduring extremely long matches, seven times over two weeks. In tennis, those who sprint don't make it to the finish line.

There's an innate tendency in human-beings to sort ourselves by how much we want power. Some of us don't want it at all, some of us are absolutely obsessed with it. The interaction between the individual and the system is therefore critical.

Rationality applies whether you believe in it or not. One idea follows from another – or it doesn't – and if you want some of your beliefs to lead to other beliefs, you have no choice but to be rational. We're committed to it by the very act of discussing, arguing, debating, persuading and convincing.

Just as you wouldn't want a surgeon to go from one operating theater to the next without having washed their hands, you don't want a manager to go from one context to the next without being in a position where they can actually do some good—or at least do no harm.