In Edinburgh last night I was watching people skating around St Andrew's Square.

Some wobbled, some fell over, some glided elegantly through the ice. There was even the odd couple swapping cold-lipped kisses as they wheeled around in perfect synchronicity. In the darkness, with the Christmas lights twinkling merrily it looked like the ideal festive scene.

I don't need to tell you it wasn't real, do I? A few feet away I stood on a soggy wooden platform, my coat buttoned up against the wind. But there was no falling snow prettifying the view, no ice to worry about slipping on. It was a cold, slightly wet, pretty drab December evening. But that's all it was. The winter signifiers - lights and ice and Christmas tunes - were all artificial additives.

Our idea of Christmas is swaddled in snow. We send cards that glitter and twinkle with visions of winter wonderlands; either Hallmark visions of Santa and his reindeer or robins on the snowy branch or reproductions of wintry paintings such as Raeburn's The Reverend Robert Walker Skating on Duddingston Loch or Pieter Bruegel the elder's The Hunters in the Snow. And yet how many white Christmases have I actually seen in my life? In 50 years and counting, maybe four or five.

Our vision of winter is the medieval vision of winter, a species memory of the little ice age that stretched from 1300 or so until around the middle of the nineteenth century (when the industrial revolution began to make its own impact on climate change). In 1565, the year Bruegel would paint his great canvas, the world froze. Queen Elizabeth I and her court even played games on the frozen River Thames at Westminster.

Bruegel's painting is full of the joy and horror of that bitter winter. Men play games on the ice and children skate happily on frozen fields as the hunters of the title and their hounds trudge wearily home with little sign of success. "Darkness stalks the hunters," the American poet Joseph Langland wrote in response to the painting, "Slowly sliding down,/ Falling in beating rings and soft diagonals." The dark is closing in. That's the story winter tells every year.

The first time I saw it the painting Vienna's Kunsthistorisches Museum years ago now it took my breath away. Just looking at it I could hear the snap and crackle of the fire off to the left of the painting, almost see my breath smoke out of my mouth and feel my lungs fur with ice.

As you look at it your eyes sweep down the valley like a bird in flight, veering away from the dangerous glassy spikes of the mountains towards the sea that looks as solid and unyielding as the icy fields. It's a perfect painting, one of those all-too-few things that makes you proud to be human.

We claim now that Charles Dickens invented Christmas as we know it and there's a truth in that. His celebration of the Victorian white Christmas is the one that we are still trying to recapture every year, a vision of food and family, happiness and a warm hearth. The Cratchits on Christmas Day.

But you can see the same things in Bruegel's painting. Here are the hunters home from the hunt wanting the warmth of the fire, the succour of a hot meal. At some level even now, more than 400 years later, we are all hunters in the snow. What is the vision of Christmas we desire? It's a vision of home. It always has been.