If you want to know why Europeans belong in a single community, visit any one of Britain's great medieval cathedrals. Walk in the cloisters at Gloucester or pay homage to William of Sens, the Norman architect of Canterbury. Or just tap the stones of this masterpiece – they come from Caen, France.
The modern dream of European political union is entering its darkest days. Eurosceptics say they are vindicated, and are realists – but nothing is less real than the illusion that any European nation, least of all ours, can lay claim to some inward-turned, singular story outside the larger narrative of the continent. For at least 1,000 years, Europe has been building a common culture.
The first European union called itself "Christendom", and in the 11th century created a shared style of art, architecture and philosophy that transcended the borders of infant states. Gothic architecture radiated like a rose window from its source in Paris and fanned out across Europe. What is more real to us today – the doings of medieval British kings, or the elegance of the gothic flying buttresses of York Minster? The petty histories of national politics that Eurosceptics see as our true island story are dull compared with the still-living glories of our European cultural history.
Europe's next cultural revolution, the Renaissance, was even more cosmopolitan. European intellectuals discovered, in the 15th and 16th centuries, a lost common classical Greco-Roman inheritance. The Renaissance spread like wildfire across the entire region. In Westminster Abbey a Florentine sculptor, Pietro Torrigiano, put golden infants on the tomb of Henry VII while, on the far side of Europe, the Hungarian king Matthias Corvinus received, as a gift from Florence, a bust of Alexander the Great. A traveller such as Erasmus could ride from Rome to Basel to London and everywhere meet friends who understood his jokes. The painting that sums it all up is Titian's Renaissance masterpiece, The Rape of Europa – a vision of the myth that gave Europe its name, painted in Venice for the king of Spain.
The EU fails to draw on the vibrancy of this common cultural history. The EU's website is called Europa, but instead of Titian's painting its opening screen is a void of blue banality. Why not make more of Europe's cultural unity? Perhaps because the very wine of Bacchus that can enthuse us about our shared identity is dangerous. A celebration of Europe's aesthetic glories should, as a matter of accuracy, also include the Muslim heritage that has interacted with Christian and classical sources in European art since the early middle ages. The fan vaulting of England's Gothic cathedrals, for instance, was influenced by Arab mathematics, as was the Renaissance discovery of perspective.
All this may sound too good to be true; as if, under the bloody, day-to-day violence of Europe's past, beneath the divisions of the Reformation and the rise of nationalism, the continent had all along been building a secret community of culture. And a secret rose that, miracle of miracles, embraces all other cultures too. But that is the historical reality. For every divisive political force in European history there has been a unifying cultural force.
All the European movements in art and architecture that we cherish today, which our museums and collections and concert halls live off, are just that, European movements. Baroque and rococo styles, the neo-classical and romantic revolts, realism in the 19th century and modernism at the birth of the 20th – all bonded artists and intellectuals and publics from Poland to Denmark. The history of Europe's common culture was not even ended by the 19th-century vogue for nationhood, for nationalism itself is a common European idea – its Romantic appetite for landscape art and poetry reproduced from one capital to another just as relentlessly as classical myths were translated across Renaissance Europe. Today, this common culture may be on the brink of its greatest achievement since Copernicus (who lived in central Europe; whose observations were tested by Tycho Brahe in Copenhagen; defended by Galileo in Rome; and proven by Britain's Royal Society) when the Large Hadron Collider at Cern makes a momentous discovery.
Some time soon Europeans who believe in a common identity need to stand up and proclaim the unique richness and openness of our culture – the purality-in-unity that means a baroque church in Sicily does not look identical to one in Bavaria. In the UK, the Art Fund is campaigning to keep a painting by Bruegel in the country. Why? Because it's our heritage. Because we are Europeans.
If Euroscepticism were to start by letting go of all the Bruegels and all the Titians, reducing the National Gallery to a room of 18th-century English portraits, its stupidity might become plain. It is not idealism to believe in Europe; still less is it a bureaucratic abstraction. If you see history in its living colours, you see how deeply European we are and how profound are the roots of that common identity.
