The middle ages invented fine art ... and Britain itself

The medieval world is caricatured as ignorant and filthy, but the strong central state that emerged sponsored art of huge ambition
Durham Cathedral
The royal Norman origins of medieval high art are obvious in masterpieces such as Durham cathedral. Photograph: Alamy

What did the middle ages ever do for us? This week, my Guardian series The Story of British Art enters the age of castles, cathedrals and brightly painted manuscripts. The medieval world is the most misunderstood and underrated of all cultural epochs. It is caricatured as barbarous, ignorant and filthy. In reality, as I think my favourite works of medieval British art like today's Chapel of St John's show, we owe a huge amount to the middle ages. This is the age that truly invented fine art, the worship of beauty and the idea that art can change your soul. It also invented Britain.

I've become aware, looking at early British art, how it was made by many different cultures that came and went on these islands. This place was a cultural football kicked back and forth. No single national identity existed. The islands were full of noises in different languages, not to mention runic inscriptions left by Vikings that look like magic spells out of The Lord of the Rings. But suddenly in 1066 William the Conqueror founded a monarchy that with some twists and turns is still going. England's strong central state sponsored art of huge ambition. Great cathedrals started to rise, like Durham, which goes right back to early Norman times. The royal Norman origins of medieval high art in Britain are obvious in the Chapel of St John's, which dates from just a few years after 1066 and is part of William's White Tower.

Chapel? Cathedral? Aren't those architecture? But this is the fantastic, and very contemporary, thing about medieval art. Knights in armour did not fuss about where art ended and a building began. They created all-encompassing atmospheric environments, installations in stone and glass. In museums, medieval art can seem remote, because it was never made for museums. It was made to be part of life, to illuminate a theatre of worship, war, or love.

Art was incredibly serious in the middle ages. It had to reveal heaven and cleanse the soul. It had to tell stories that illiterate peasants could understand. A lot of Britain's medieval heritage was destroyed in the Reformation by two devastating onslaughts – Henry VIII's ransacking of monasteries and the iconoclastic rage of the Puritans. But choice selections to come in The Story of British Art show how many wonders survive. The middle ages made us who we are.