Stories are alive. The ones that last, Gaiman said, outcompete other stories by changing over time. They make it from medium to medium—from oral to written to film and beyond. They lose uninteresting elements but hold on to the most compelling bits or even add some. The most popular version of the Cinderella story (which may have originated long ago in China) has kept the gloriously unlikely glass slipper introduced by a careless French telling.