Justify the title "Gift of the Magi"?
In the very last few lines of the story, the narrator justifies the title:
Of all who give gifts, these two were the most wise. Of all who give and receive gifts, such as they are the most wise. Everywhere they are the wise ones. They are the magi.
The title "The Gift of the Magi" is a biblical allusion to the wisemen who visit Christ and bring gifts like gold and spices. The heart of the story by O. Henry is the idea of gift giving at Christmas time. In the final moments of the story, O. Henry clarifies the significance of the title:
The magi, as you know, were wise men—wonderfully wise men—who brought gifts to the Babe in the manger. They invented the art of giving Christmas presents.
O. Henry makes the argument that although Jim and Della may have acted foolishly, their gifts were selfless. In both cases, the character sacrificed what they loved to procure something for the person they cared about most. The title "The Gift of the Magi" reinforces O. Henry's larger theme about gift-giving; the gift itself is not nearly so important as the consideration and love put into it. The Magi brought gifts to honor newborn Jesus; Jim and Della's gifts also pay tribute to their selfless love.