“‘Twas the night before Christmas and all through the house, not a creature was stirring, not even a mouse…”

You probably know what happens next. But do you know who wrote this poem, and when? Do you know where the tradition of the Christmas tree comes from? Lights on the Christmas tree? Stockings? Even the idea of gift-giving?

No holiday has a richer and more varied tradition than Christmas. So let’s look into its history and see if we can uncover some of that richness and tradition. And if you don’t celebrate Christmas—well, at least you’ll have a better appreciation of why so many people do.

Here’s what everybody knows:

Christmas is when Christians celebrate the birthday of Jesus Christ. That in itself is a very big deal. Christianity, in all its many iterations, remains the most popular religion in the world. Two billion people follow it.

Aside from its obvious religious significance, the first Christmas stands as the great divide for the recording of human history. Until recently, history was divided between BC (Before Christ) and AD (Anno Domini, which is Latin for “Year of Our Lord”). Now you’ll often see BCE (Before the Common Era) and CE (Common Era). No matter. The divide is still Jesus’s birth.

The great kings of the first millennium recognized the significance of the day and attached themselves to it. Charlemagne, Alfred the Great, and William the Conqueror, among many others, were either baptized or coronated on December 25.

The idea of Christmas as a time of gift-giving also goes back to the earliest days of Christianity. The story is told that a third-century church bishop, Nicholas, would anonymously throw bags of gold coins into the windows of the poor. The coins supposedly landed in the shoes or stockings that were drying by the fireplace. Thus, was the stocking stuffer born. After Nicholas died and was declared a saint, his popularity and positive Christmas message spread across Europe, each nation adding its own distinct contribution.

In Germany, the winter tradition of placing evergreens in their homes took on a new significance in the 16th century when Protestant reformer Martin Luther put candles in the branches. He told his children the lights were like the sky above Bethlehem on the night of Christ’s birth.

The idea that St. Nicholas would judge whether you’ve been good or bad during the year stems from the Book of Revelation in the New Testament, which depicts Christ returning to Earth riding a white horse. In the Middle Ages, the legend sprang up that Saint Nicholas had been chosen as the Savior’s advance guard. He wouldn’t come at the end of the world, but every year to check things out and give a report.

When this notion arrived in Norway, it encountered a problem: there were no horses in Norway. But they did have plenty of reindeer. And, of course, Norway abuts the Arctic Circle and the North Pole, so St. Nick found himself with a new domicile.

All these various European traditions came together in the great melting pot of America.

In New York in 1823, a professor at the Protestant Episcopal Seminary, Clement Moore, wrote a poem for his children, 'Twas the night before Christmas:

“…The stockings were hung by the chimney with care,

In hopes that St. Nicholas soon would be there…”

The poem caught on and became a Christmas staple every school child could recite.

The holiday got another push in 1843, when the great British writer, Charles Dickens, published his short novel, A Christmas Carol. The redemption of Ebenezer Scrooge perfectly captured what we now refer to as “the Christmas spirit”: the idea that the holiday brings out the best in all of us.

As the new century turned, Hollywood got into the act. Almost as soon as there were movies, there were movies celebrating Christmas. To this day, a year doesn’t go by without a new one.

Madison Avenue saw a big opportunity, too. In 1931, Coca-Cola hired artist Haddon Sundblom to create a Christmas ad of Santa Claus (which is Dutch for St. Nicholas) drinking Coke. The jolly white-bearded fellow in a bright red suit remains the personification of Old St. Nick.

And, in perfect melting-pot fashion, Irving Berlin, the son of a rabbi, wrote the definitive yuletide song, “White Christmas.”

Many complain today that the religious aspect of Christmas has been overwhelmed by commerce. Retail sales between Thanksgiving and Christmas are now $1 trillion. This is not a new complaint. The Puritans refused to celebrate Christmas because they thought it trivialized the holiday’s religious message.

But this remains the minority view. Most people love Christmas and all the things—the lights, the tree, the songs, the movies, and, yes, the gifts—that come with it. And who can deny that people tend to act a little nicer, a little happier, as the special day draws near?

In a world that feels so divided, Christmas still unites us. For that, we should all be grateful.

I’m William Federer, author of There Really Is a Santa Claus, for Prager University.