Medieval theology held that Jewish men menstruated as divine punishment

Evidence

The idea that Jewish males were subject to periodic bleeding similar to women’s menstrual cycles, bizarre though it might appear, was to become an issue of theological debate in the University of Paris in the early fourteenth century, when it was argued that there were ‘natural’ differences between Jews and Christians analogous to those between the sexes. In the 1220s, however, Jacques de Vitry, developing the theme linking the Jews’ unwarlike nature to femininity, and in particular to the monthly effusion of blood, attributed the phenomenon to divine punishment for Cain’s murder of Abel. — James Renton, Ben Gidley (eds.), Antisemitism and Islamophobia in Europe, 205

Categorization

• CANDY: The fact that medieval Paris scholars debated whether Jewish men menstruate is a striking, easily-shared oddity.
• QUESTION: Worth chasing: how widely held was the male-menstruation belief, and how does it map onto the later medieval blood-libel bloods?