Dan Heath's book Upstream: The Quest to Solve Problems Before They Happen begins with a parable: A couple of guys picknicking next to a river notice a young child floating down the river about to drown. They jump in and rescue the child, but then see another child coming down the river. They rescue this child as well, but then notice a long line of additional children approaching. One of the guys gets out of the river and runs upstream. "Where are you going?" shouts