we’re trying to make use of details or patterns, portions of some prior story (or, once you really start thinking like a professor, “prior text,” since everything is a text) to add depth and texture to your story, to bring out a theme, to lend irony to a statement, to play with readers’ deeply ingrained knowledge of fairy tales. So use as much or as little as you want. In fact, you may invoke the whole story simply by a single small reference.
