In the Greco-Roman world, the bean belonged to Hades, the realm of the dead. It was the food of the dead. In the Pythagorean communities, the eating of beans was strictly forbidden; beans were taboo because they belonged to the ancestral spirits.
Von Franz establishes the bean’s primary symbolic register as chthonic and funerary, drawing on Greco-Roman and Pythagorean traditions to ground its underworld significance in the fairy-tale context.
, Archetypal Patterns in Fairy Tales, 1997thesis