“In talking about sustainability I like to use a metaphor of sport, of a game. When you are in a sustainability exercise it is possible to lose. You can be unsustainable. But the converse doesn't hold. There is no point at which you can say that you have won. Sustainability consists of staying in the game; that is, continuing with the ability to solve problems. It is like a dance where you must be constantly in motion. There is no point where you can rest and say "Aha! We are sustainable!" It is something that always requires adjustment.”