One of five notable books on Christmas history he discussed with Alec Ash at The Browser:
The Origins of ChristmasRead about another book Forbes tagged at The Browser.
by Joseph Kelly
This is another brief book accessible to general audiences, written by a Catholic religious studies professor in the US. He talks about what the limited Biblical evidence is for Christmas, and where we got some of the other traditions. Much of our Christmas story isn’t really in the Bible – in order to develop a big birthday celebration we’ve added all kinds of traditions. This book looks at the origins of St Nicholas, the Magi, and so on.
What does he say about St Nicholas?
He talks about how St Nicholas is really a legendary figure. It’s difficult to tell what is historical and what is legend, but the legends are I think marvellous. He was a bishop in the 4th century in what’s now Turkey, and gained a reputation for generosity, and for caring for young children and travellers. As a saint he almost became the equivalent of a guardian angel. He became very popular, and his saint’s day, December 6th, at least was in the month leading up to Christmas. So over time he became associated with Christmas celebrations. Then, when the legend got to the States, and especially to New York, St Nicholas morphed into Santa Claus.
Tell me more about how that happened.
Well, New York was founded as New Amsterdam, with Dutch beginnings. And the Dutch kept alive the tradition of St Nicholas where many other countries, influenced by Protestantism, had de-emphasised him. So St Nicholas hopped the waters with the Dutch to New York. Then, in a very complicated story in which you would have to trace five or six steps because of one person or another’s influence, he morphs and becomes de-frocked.
In Washington Irving’s writings, he is a Dutchman who rides a wagon pulled through the air by horses on St Nicholas’s day. Then later on, with the famous  poem “Twas The Night Before Christmas”, he moves to Christmas day and gets reindeer.
In that poem, as you point out in your own book, St Nicholas is an elf.
Yes, which is a complete surprise for most people. If you buy a picture book of that poem, the illustrations are usually of the full-size, jolly, red and white Santa Claus. But if you read the words of the poem, he’s an elf – not just in the phrase “the jolly old elf”, but it talks about “a miniature sleigh”, “tiny reindeer” and his “little round belly”. He’s an elf. So he still has to morph more, through the art of [19th century American cartoonist] Thomas Nast and then the advertisements of Coca Cola, until he becomes our modern image of Santa Claus.
Also see Penne Restad's five best list of books on Christmas traditions.