" Only in a national economy that is largely self-contained can a national central bank be a true central bank; with the development of world market, and (especially) of world financial markets, national central banks take a step down, becoming single banks in a worldwide system, not at the 'centre' any longer. Thus the problem that was (partially) solved by the institution of national central banks has reappeared, and it is still unsolved (though we are trying to solve it), on the world level. "

― John Hicks