"One of the chief sources of irritation for the interpreter of fairy tales is the nature of folkloric sources. For nearly every tale, that are at least a dozen versions, in some cases, hundreds of extant variants. In other words, rather than a single, stable literary text in which even the finest points of detail may function as bearers of significance, we have an infinite number of corrupt "texts," spoken and written, each representing one version of a single tale type, and an imperfect version at that. No matter how gifted the transcriber of a tale is, he cannot fully succeed in capturing and recreating the spirit of an oral performance. Much as fairy tales invite interpretation, the facts of their origin and diffusion imply the impossibility of textually grounded interpretation. Even the anthropologist who can go straight to the source, observe the teller, study the community in which a tale flourishes, and record that tale still has nothing more than a single version, one no more and no less authoritative than other oral variants.
. . . "Any attempt to unearth the hidden meaning of fairy tales is bound to fail unless it is preceded by a rigorous, if not exhaustive, analysis of a tale type and its variants. That analysis enables the interpreter to distinguish essential features from random embellishments and to identify culturally determined elements that vary from one regional version of a tale to the next."
Maria Tatar, Hard Facts of the Grimms' Fairy Tales, pp. 42-43