Our culture has no concept of stopping. We continue to build motorways and airports for a future in which cars and planes may no longer exist. We're converting our planet from a natural one to an artificial one in which the quantity of man-made objects ? houses, asphalt, cars, plastic, computers and so on ? now exceeds the totality of living matter. And while biomass continues to decline due to deforestation and species extinction, the mass of man-made objects is growing faster than ever. We're on a treadmill to disaster. To get off this treadmill, argues Harald Welzer, we need to learn how to stop: as individuals and as societies, we need to stop doing what we're doing and say 'enough'.