Myth
From Generative Anthropology
Myths are the narrative explanations which aim to explain failures in ritual.
Origin
In cases where the center fails to fulfill promises made in ritual, myths provide narrative explanations for this failure (maybe the "sacred being" has a lesson to teach, or the community "didn't really" perform to divine instructions) which sharpen the ritual, making it more likely the ritual is performed successfully the next time.
Characteristics
Myths are fundamentally declarative - they are new ostensives generated in response to a failure of a previous ostensive.