My 8-year-old son desperately needed a heart transplant, and we were told a young girl who had recently died was a match. The surgery was successful, but two weeks later, the girl’s mother found us and handed me a small music box. She told me her daughter used to play it every night and once said her heart was “too big for her body” because it was always racing. Then she gave the music box to my son, saying, “I need him to have this, so when he can’t sleep, he’ll hear what her heart sounded like before it was his.” I was overwhelmed by the compassion of a mother who had just lost her child yet still wanted to give my son a piece of her daughter’s life. Now he plays the music box every night and says, “Mom, when the music plays, my chest feels warm.” He doesn’t yet understand where his new heart came from, but one day I’ll tell him about the little girl who gave him everything she had—and the mother who made sure that incredible gift came with a song. …