Who are the Magi in O. Henry's short story "The Gift of the Magi" and why?

O. Henry intrudes at the end of the narrative of his short story, "The Gift of the Magi," and declares that Della and Jim are the Magi. This young married couple is considered the Magi because, like the three kings who came to see the baby Jesus, they give valuable gifts unselfishly.

Despite the fact that O. Henry states that the Magi gave wise gifts and Jim and Della are "two foolish children who most unwisely sacrificed," he yet compares the young husband and wife to the Magi: 

Of all who give and receive gifts, such as they are wisest....They are the wisest.

While this statement seems paradoxical when considered with the previous one that they "unwisely sacrificed," nevertheless, Jim and Della are wise in the sense that they understand the value of love. For, no material possession is as important as the happiness of the beloved. This Jim and Della understand because they have sacrificed their personal treasures in order to make their beloved spouse happy. In this sense, then, they are "the wisest." Like the magi, they have given valuable treasures up to the beloved.