On Roots of the Myth of Jewish Male Menses in Jacques de Vitry's History of Jerusalem
Traces the attempt by Christians to find a "motive" for alleged Jewish ritual murders of Christians from the 12th century, when there were more Christian polemical treatises against Jews than in all previous centuries. The search for an explanation of ritual murder led to a fusion of theological and natural scientific notions. Jewish males were believed to have a flux of blood via hemorrhoids, both due to theological considerations (see Mathew 27:25, "His blood is on us and on our children, " and interpretations of Samuel 5:6-12 and Ps. 77:66) and contemporary medical ideas (that a defective diet and life-style, including melancholy, fear, and idleness, caused bleeding). These were combined in de Vitry's "History of Jerusalem" (ca. 1221), which was apparently the first literary source to state that, like women, Jewish men had monthly flows of blood. The conclusion drawn by Christians was that Jews believed that this ill and others could be cured by using Christian blood, rather than by conversion to Christianity where they might be saved by the blood of Christ. This "explanation" of the Jews' alleged need for Christian blood was actually cited at trials for ritual murder.