The repetition of events, characters, or tests in groups of three, one of the most fundamental structural devices in fairy tales.
The Rule of Three is perhaps the most pervasive structural pattern in oral storytelling worldwide. Characters appear in threes (three brothers, three wishes, three tasks), events repeat three times with increasing stakes, and tests come in sets of three. This pattern serves multiple functions: it creates rhythm and predictability in oral performance, builds dramatic tension through repetition with variation, and satisfies a deep cognitive preference for triadic structures. The third instance typically breaks the pattern — the youngest brother succeeds where the first two failed, the third wish undoes the damage of the first two, or the third attempt finally succeeds. Examples include Three Little Pigs, Goldilocks and the Three Bears, and the three tasks in countless quest narratives.