The Decretum of Buchard of Worms, compiled between 1008 and 1012, lists the spells and incantations resorted to by women; most of them involve manipulating food -- for example, increasing or decreasing the sexual ardor of a husband by adding to his food such things as menstrual blood, semen, or dough kneaded with a woman's buttocks.

— Holy Feast and Holy Fast by Caroline Walker Bynum (The new historicism : studies in cultural poetics)