The old nation-states of Europe, and those who lead movements that aspire to become new European nation-states, live in the contradiction of proclaiming their sovereignty but at the same time having accepted decisions in the recent decades that imply the transfer of their sovereignty to the European level. This is most clear in the Eurozone, where member states have transferred monetary sovereigty to the European Central Bank, and fiscal sovereignty to the fiscal rules associated to the zone. The increasingly consensus view is that this transfer of sovereignty is insufficient, and that it should be accompanied by a European Treasury with a large budget and taxation powers, accompanied by some legislative mechanism that complements the European Parliament. But also countries that are not members of the Eurozone live under the myth of sovereignty. British voters were called to vote in a referendum some weeks ago under the premise that the decision to leave the European Union was in their hands that day. Their "independence" and their "freedom" was at stake that day. Their surprise came the very day after the vote, when they heard their government, and the leaders of the Brexit campaign, argue that, contrary to what had been said during the campaign, they would delay the official request to leave the Union, because to leave, a negotiation that would last at least for two years would be necessary. They also learned that the decision to leave was subject to many constraints: you couldn't just leave and cherry pick some aspects of the relationship with the rest of Europe. In particular, they could not pick free trade and abandon free movement of citizens at the same time. The EU will not accept it. The British voters are not as sovereign as to cherry pick which aspects of Europe to retain and which to discard. At the same time, below the UK level, some sub-national levels began to claim some degree of sovereignty. It turns out that the fact that the Brexiteers had not won in Scotland, London, Gibraltar or Northern Ireland is a very significant fact that complicates the decision to leave for a variety of reasons. Whose is the sovereignty? Which is the relevant "demos"? These are old questions, questions that the evolution of Europe in the last decades, with all its problems, has made obsolete. Sovereignty is shared. If the UK, an old imperial nation with a consolidated democracy, is not fully sovereign, the implication for member states of the Eurozone and for aspiring new nation-states is obvious.