On December 24, 1920, J.R.R. Tolkien sat down in his study and wrote a letter to his three-year-old son, John, who had recently asked about Father Christmas. In spidery handwriting, in red ink, Tolkien replied as Father Christmas (the English folkloric figure now widely equated with Santa Claus), addressed from “Christmas House, North Pole.”

The accompanying picture that he drew is charmingly Tolkien-esque. A red-coated figure with a long white beard and a rosy red nose walks through the snow. His dome-shaped house glows from a wintery hillside, at the end of a staircase lit with lanterns.

For the next 23 years, every Christmas Eve, Tolkien wrote a letter to his four children from Father Christmas. What began as short, informative letters—“I am just now off to Oxford with a bundle of toys”—evolved into longer tales about life at the North Pole. The 1932 letter begins, “Dear Children, There is alot to tell you. First of all a Merry Christmas! But there have been lots of adventures you will want to hear about. It all began with the funny noises underground … ”

Drawing of the aurora borealis, 1926. © The Tolkien Estate Ltd 1976

What follows is a tale of a beloved polar bear, mysterious caves filled with goblins, and their heroic counterparts, the Red Gnomes. As with The Hobbit, which Tolkien wrote and published in this period, the letters contain entire worlds, with invented languages and histories, alongside detailed illustrations.

Even the methods of delivery for the letters were as authentic as possible. They were presented to his children in envelopes with North Pole postage stamps—two kisses per letter—and later Tolkien persuaded the postman to include them in his mail deliveries.

Next year, you will be able to see these letters at Oxford’s Bodleiean Libraries exhibition Tolkien: The Maker of Middle-Earth, along with a trove of other Tolkien artifacts. Atlas Obscura has some images of the letters, which will be on view from June 1 through to October 28, 2018.

Drawing, 1932. © The Tolkien Estate Ltd 1976

First page from Father Christmas letter, 1932. © The Tolkien Trust 2012