##imum - currency - area odyssey ”, journal of international money and mongelli, f. p. ( 2002 ), “'new ’ views on the optimum currency area theory : what is emu telling us? ”, working paper series, no 138, ecb finance, vol. 28 ( 7 ). 3 european commission ( 2019 ), standard eurobarometer 91 – spring 2019. 4 otero - iglesias, miguel ( 2017 ), “ the euro as a social bond : why do eurozone citizens still back the single 4 / 5 bis central bankers'speeches currency? ” real instituto elcano, 25 / iv / 2017. 5 / 5 bis central bankers'speeches

decision. it is the result of successive political decisions and the evolution of the european integration process. the euro is a logical and necessary consequence of the single market. currency fluctuations – even when resulting from the normal functioning of the markets – translate into subsidies / penalties for economic agents and create uncertainty. they distort competition, generate trade reallocations not based on economic fundamentals and cause social discontent. it was evident that the exchange rate mechanism of the european monetary system was not compatible with the degree of openness of the economies participating in the single 1 / 5 bis central bankers'speeches market and the existence of autonomous monetary policies. it was this inconsistency that led to the 1992 – 1993 currency crisis, which clearly showed in practice that an internal market without a single currency is necessarily an unstable equilibrium. the euro has safeguarded the integrity of the single market and has delivered two decades of price stability. the euro has fostered confidence and brought important and tangible benefits to european households, businesses and governments. naturally, it has also introduced new requirements with regard to the behaviour of economic agents as well as new rules and institutions. it made the need for adequate policies, sound public finances and financial discipline of private actors more visible. a single currency implies a single monetary policy and, in a context of markedly heterogeneous national revealed preferences, there is a risk of inconsistency between national economic and fiscal policies and the common monetary policy. it was therefore clear from the outset of emu that it would be necessary to create discipline, rules and institutions that would reduce disparity in order to ensure stability. the emu rests on a comprehensive set of rules and on a non - federal institutional framework based on a sharing of sovereignty between member states and, above all, on mutual trust. this means that its success hinges on its members making every effort to understand each other and to mutually realise their interests. in a nutshell, the euro is the result of a dialectic process between solidarity and responsibility towards a common good. the functioning of emu is based on permanent negotiation and approximation of different starting positions, safeguarding national cultures and identities while guaranteeing a sense of belonging and a “ group identity ”. this implies an institutional framework with a great capacity to understand and manage differences and to facilitate the interaction between the interests of the whole and the specificities of the parts. the principles of collective ownership and consensus must always be kept in mind. the european regulatory framework and the architecture of