The diversity of Europe is its strength. But for a single currency to work, over a region with enormous economic and political diversity, is not easy. A single currency entails a fixed interest rate, which means countries can't manage their own currency to suit their needs. You need a variety of institutions to help nations for which the policies aren't well-suited. Europe introduced the euro without providing those structures.

In the wake of the global financial crisis, there is a consensus that the world needs good regulators to ensure that the financial sector serves society in a way that it should and does not wreak havoc. But it is not an easy task. Regulators need to be smart enough to to understand the market's complexities and not be captured by its easy nostrums, devoted enough to public service that they accept earning a pittance compared with what someone of their talents could make in the private sector, strong enough to resist its enticements, and politically astute enough to manage a politics charged with money. Hong Kong has been lucky to have such a regulator in the form of Andrew Sheng.