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Quote :Morphology of the Folktale
"Functions of character serve as stable, constant elements in a tale, independent of how and by whom they are fulfilled. They constitute the fundamental components of a tale.
The number of functions known to a fairy tale is limited."
Characters take certain actions in tales (folktales, fairy tales, you name it). A bad guy, for instance, will deceive a good guy. A prince will rescue a princess. These actions or functions will recur again and again in fairy tales, regardless of which character takes them. The good guy can also deceive the bad guy (and win in the end!). Or a princess can rescue a prince (in a feminist fairy tale). Even if the characters who take these actions change, the actions themselves don't change from tale to tale.
The number of functions that appear in fairy tales, according to the calculations of Mr. Propp, is precisely 31.
Propp's study of folktales was pretty revolutionary because it was the first time that someone tried to analyze the structure of narratives that seemed totally different on the surface. It was also the first time that someone tried applying structuralist ideas to literature.