Technological revolutions are very hard to predict. My favourite example is someone in 1850 taking care of horses as a farrier. They would have said, "Look, horses have been part of human existence for 5,000 years. We are horse people. It's permanent." But all of a sudden, the internal combustion engine comes along and, with it, oil fields and automobiles, which basically replace the horse completely. So we often have these long periods of stability and then a sudden inflection point.