During my high school days, I was a pretty decent golfer (about a 2-3 handicap, for you other golfers out there). I was asked by my local club professional if I would help him teach his junior golf clinics that summer. If you have specialized skill in any sport, there are definitely opportunities out there for teaching others the fundamentals (and getting paid).

Essentially the same thing happened in China with clocks: one emperor's decision abolished clocks over China. China was also on the verge of building powerful water-powered machinery before the Industrial Revolution in Britain, but the emperor said "Stop," and so that was the end of the water-powered machinery in China. In contrast, in Europe there were princes who said no to electric lighting, or to printing, or to guns. And, yes, in certain principalities for a while printing was suppressed. But because Europe in the Renaissance was divided among 2,000 principalities, it was never the case that there was one idiot in command of all Europe who could abolish a whole technology. Inventors had lots of chances, there was always competition between different states, and when one state tried something out that proved valuable, the other states saw the opportunity and adopted it. So the real question is, why was China chronically unified, and why was Europe chronically disunified? Why is Europe disunified to this day?