The symbolic logic of the fairy tale
Fairy tales operate according to a symbolic logic that is different from realistic narrative: the rule of three, the prohibition that must be violated, the helper who appears when the protagonist is lost, the impossible task that is accomplished through the right quality of heart or the right alliance. Writing fairy-tale retellings requires understanding this symbolic logic well enough to use it intentionally — to know which elements of the tale are operating symbolically, what they are symbolizing, and what it means to change them. The retelling that changes the rule of three without understanding what the three repetitions accomplish (the escalating test, the two failures that make the third success meaningful) has changed a formal element without understanding its function.