This is because a monetary union is stable only if each country keeps its own house in order; this has been made abundantly clear by the repeated discussions on financial assistance for Greece. This was something that was pointed out in a speech delivered here at your club, La Redoute, more than 25 years ago.
The former Bundesbank President Hans Tietmeyer was already aware of the pitfalls back then and said that “Without sufficient stability policy convergence and, above all, greater budgetary discipline in a number of European countries, economic and monetary union will be unable to gain a sustainable foundation.