The article discusses what conditions make a European Monetary Union work well. It says that for the Union to be successful, countries need to have similar policies, small amounts of money, a careful European Central Bank, and national banks that rely on the European Central Bank. It also looks at how a country's policies affect the rest of the Union once the Union is formed. The article suggests that keeping an eye on countries' policies may be important, depending on how money is managed in the Union.