For years I heard sleigh bells on the roof each Christmas Eve. Once I woke my older sister, who slept in the same room, and told her so.She didn't believe me, though I kneeled on her bed and crossed my heart. I suspect she was jealous. At any rate, I kept the knowledge to myself after that, confident in the superiority of my hearing.

And then, one year, I was humbled. I can't remember how I knew, but I can still feel the awfulness of the realization as I lay in bed that Christmas Eve.

In some ways Christmas was the same. I could still hear the cars passing in the rain on the street outside. I could smell the ham cooking, for my mother always cooked a ham on Christmas Eve. My grandfather ate it the next day because he didn't like turkey.

And I could still hear my mother and father, my uncles and aunts, talking downstairs, slowly, with long pauses, as they always talked when they got together -- a way that made you glad to leave and go to bed.

"Remember Ruth Mitchell? Peter's daughter. No, Ron's daughter. You had a shine on her, Tom. No. No. Married the Davis boy. Lived in Macky's place up on Burnt House Hill. Whatever happened to Macky? That used to be all fields up there, and trees, when I was a small boy coming up."

All that was the same but the next morning I did not rush to the row of stockings in the living room. Instead, I slunk from my room when I was summoned, conscious of knowing something bad that I was not supposed to know. The excitement was replaced by a queasy guilty feeling I never felt before. It was a long time before I told my parents I knew.

So it was for many of us, and the memory clings.

Suddenly Santa -- the real live Santa who touched down on rooftops and squeezed through chimneys -- was gone and Christmas had changed. Whether Santa fell first, and other illusions followed, or whether Santa no longer fit in a universe that was larger and far less perfect than we ever imagined, is impossible to tell. But there was little doubt of the result. A brief, wonderful part of our lives had slipped away and pieces of perverse reality pushed forward to confront us.

It was the first of many such changes within us, in a wider, more confusing universe, that stretched much farther than the North Pole, farther than even a letter to Santa could reach. All sorts of realizations came crowding in that made Santas, Easter bunnies and tooth fairies seem like small fry. What is the loss of Santa compared to the realization that your very own parents are less than perfect? They cannot even tell us, with any precision, why we were born. Or why we will die, possibly violently, probably unexpectedly. The queasy guilty feeling often returns.

We read in the papers that so many Christmas turkeys and trees will be bought and sold. A particular number of people will die on the highways and so many old ladies will eat their dinners alone in cold apartments.

But no one, as far as I know, has tried to calculate the number of children who will stop believing in Santa Claus this Christmas. Their loss, of course, is immeasurable. And try as they will, the simplicity and clarity of that too-short time cannot return.

Our family is scattered now, but we will travel from four different countries to be together this Christmas. And sometime over the next few days, my older sister will remind me of the sleigh bells I heard when I was small. She always does.

And I, once more, will deny I ever heard them. But it will be a lie. Nothing was ever so clear and so certain as the sound of sleigh bells on the roof, on Christmas Eve.