Why do the rural dead beg for food?

There is a custom of offering sacrifices to the seventh person in the mourning ceremony for the elderly in France. According to the lunar calendar, if a person dies within 7749 days of the seventh, seventeenth and twenty-seventh day of the first lunar month, it means that the deceased is guilty and the descendants will suffer for it, and begging for food for three days is also called begging for filial piety. When the dutiful son wants to be filial to rice, he wears mourning clothes and holds a rice bag in his hand. Every time he went to a house, he knelt on the ground and asked others to give him filial piety. On this day, the host family is also very generous, generally giving him a liter and a half.