William Sydney Porter (1862-1910) is better known as the great American short story writer O Henry. He was an absolute master of the form, and his work often showed profound insight into human faults and foibles. Some of this was probably due to his own life experience – he had a colourful past, serving time for embezzlement and fleeing to Honduras to evade arrest, where he lived with a notorious train robber and coined the term "banana republic" in a novel he wrote there.

One of O Henry's stories has a Christmas title, and it's guaranteed to reduce even the most stony-hearted reader to tears. The Gift of the Magi tells of Jim and Della, newly married and existing on air. [Spoiler alert! If you don't want to know how it ends, don't read on.]

It's Christmas Eve, and Della has precisely one dollar and 87 cents to spend on Jim's present. But she also has the most beautiful head of hair ("Had the Queen of Sheba lived in the flat across the airshaft, Della would have let her hair hang out the window some day to dry just to depreciate Her Majesty's jewels and gifts.") It's her pride and joy, just as Jim's fine gold watch, handed down from his father and grandfather, is his – and hair had a monetary value. She sells it for 20 dollars to buy Jim a worthy watch chain.

When Jim comes home, he stands shocked at her transformation, but she hands over her gift with love and pride. And he – still stunned – hands over his: a set of beautiful combs for her hair, which he's paid for by selling his treasured watch.

The magi, O Henry notes, were wonderfully wise and no doubt gave wise gifts. "And here I have lamely related to you the uneventful chronicle of two foolish children in a flat who most unwisely sacrificed for each other the greatest treasures of their house. But in a last word to the wise of these days let it be said that of all who give gifts these two were the wisest. Of all who give and receive gifts, such as they are wisest. Everywhere they are wisest. They are the magi."

This isn't a story that claims to be biblical exegesis. But it is about the wisdom of love, that gives without counting the cost, because the beloved is worth it; and in that there's something not just human, but divine.