Here's why:
* The Magi: In the biblical story, the Magi were wise men who traveled a long distance to bring gifts of gold, frankincense, and myrrh to the newborn Jesus. Their gifts were not simply material possessions, but represented profound love and respect.
* Jim and Della's Sacrifice: Jim and Della are portrayed as being incredibly poor, yet they each sacrifice their most prized possessions – Jim's heirloom watch and Della's beautiful hair – in order to buy a gift for the other.
* Love and Wisdom: Their actions demonstrate a deep love and understanding of their partner's needs and desires, even if it means making a great personal sacrifice. Their choices are "wise" in the sense that they prioritize love and giving over material possessions.
Therefore, O. Henry compares Jim and Della to the Magi to highlight the selfless nature of their gifts and the wisdom of their love. The story ultimately emphasizes the value of love and sacrifice over material wealth.