Pan-European identity is the sense of personal identification with Europe, in a cultural or political sense. The concept is discussed in the context of European integration, historically in connection with hypothetical proposals, but since the formation of the European Union (EU) in the 1990s increasingly with regard to the project of ever-increasing federalisation of the EU. The model of a "pan-European" union is the Carolingian Empire, which first defined "Europe" as a cultural entity as the areas ruled by the Roman Catholic Church, later known as "Medieval Western Christendom" (which extended its scope further eastwards to the shores of the Baltic Sea during the course of the Middle Ages). The original proposal for a Paneuropean Union was made in 1922 by Count Richard von Coudenhove-Kalergi, who defined the term "pan-European" as referring to this historical sense of the western and central parts of continental Europe encompassing the cultures that evolved from medieval Western Christendom (ie: Catholic and Protestant Europe, with the exception of the British Isles) instead of the modern geographic definition of the continent of Europe. Coudenhove-Kalergi saw the pan-European state as a future "fifth great power", in explicit opposition to the Soviet Union, "Asia", Great Britain and the United States (as such explicitly excluding both the British Isles and the areas that were influenced by Byzantine Christendom, which are usually considered a part of geographical Europe, from his notion of "pan-European"). After 1948, an accelerating process of European integration culminated in the formation of the EU in 1993. In the period from 1995–2020, the EU has been enlarged from 12 to 27 member states, far beyond the area originally envisaged for the "pan-European" state by Coudenhove-Kalergi (with the exception of Switzerland), its member states accounting for a population of some 447 million, or three-fifths of the population of the entire continent. In the 1990s to 2000s, there was an active movement towards further consolidation of the European Union, with the introduction of symbols and institutions usually reserved for sovereign states, such as citizenship, a common currency (used by 20 out of 27 members), a flag, an anthem and a motto (In Varietate Concordia, "United in Diversity"). An attempt to introduce a European Constitution was made in 2004, but it failed to be ratified; instead, the Treaty of Lisbon was signed in 2007 in order to salvage some of the reforms that had been envisaged in the constitution. A