A sweet Christmas story, originally told by Maria Montessori:

One day a mom finally decided to let her little boy know that Santa doesn't actually exist. When she told him, he started to laugh and said, "Oh, Mamma! I've known for a long time that Santa Claus didn't exist!" Surprised, the mom asked, "But why didn't you ever tell me?" To which the boy replied, "Because it always made you so happy."

--Maria Montessori, from "The Child in the Family"