The 14th-Century German Cleric Who Argued the Black Death Was Not the Jews' Fault

Konrad of Megenberg (1309–1374) was a Bavarian cleric and natural philosopher of the second rank — a former Paris-trained theologian, the cathedral schoolmaster at Vienna in the 1330s, and from 1342 a canon of the Regensburg cathedral chapter. He is principally remembered today for his German translation of Thomas of Cantimpré’s Liber de natura rerum (the Buch der Natur, 1349-1350), which is one of the foundational texts of German vernacular natural philosophy.

He also wrote a small Latin treatise during the 1349 Black Death — Concerning Mortality and Earthquake in the City of Vienna — that argued the well-poisoning accusations against European Jews were factually false on medical and theological grounds.

The accusations

The substantial European Jewish communities had been substantially accused since approximately autumn 1348 of having poisoned Christian water sources as the cause of the advancing Black Death pandemic. The accusations had spread rapidly through the trade routes from the first documented cases (Provence, autumn 1348) into the Rhineland and South German urban centres through winter 1348-1349. Pope Clement VI had issued two papal bulls (in July 1348 and September 1348) reissuing the protective principles of the recurring Sicut Judaeis tradition and explicitly declaring the well-poisoning accusations false.

The papal interventions failed to prevent the massacres. The Strasbourg massacre of 14 February 1349 killed approximately 2,000 Jews; the Basel massacre of 9 January 1349 killed approximately 600; the Cologne, Frankfurt, Mainz, Worms, and Augsburg massacres of February-August 1349 killed approximately a further 8,000-12,000 across the Rhineland-South German axis.

What Konrad argued

Konrad’s Concerning Mortality treatise was short (approximately 4,000 Latin words) and organised around three empirical arguments.

The first was chronology. The plague had reached Vienna and Regensburg in approximately the same chronological window as it had reached the Christian populations of the neighbouring towns; the Jewish populations of Vienna and Regensburg had died of the plague at the same rates as the Christian populations. If the Jews had poisoned the wells with a pathogen against which they themselves were immune, the Jewish populations should have survived at higher rates than they did. The empirical data showed they did not.

The second was geography. The well-poisoning accusations required coordinated action across the European Jewish population. The geographical pattern of the plague advance — the classical north-northwest progression from the Mediterranean ports — did not correspond to the known geographical distribution of the European Jewish populations. The plague was spreading by the known mechanisms of commercial-shipping contagion, not by the conspiratorial-coordinated mechanism the accusations required.

The third was medical. The plague produced clinical signs (the bubonic swellings, the cyanotic skin colour, the rapid mortality) that were the same as those produced by the recorded Mediterranean plague outbreaks of the classical period. The classical sources (Galen, Avicenna) described the disease as a atmospheric-miasmatic phenomenon produced by planetary-conjunction events. The 1345 astronomical conjunction of Mars, Jupiter, and Saturn matched the classical medical framework better than the well-poisoning accusation did.

What it produced

The treatise circulated in fewer than two dozen surviving manuscript copies, all in Latin, all in cathedral-chapter and monastic-library contexts. It had no documented popular circulation through the vernacular German urban-political contexts where the accusations and the massacres were occurring.

The massacres continued through 1349. Konrad’s empirical-medical arguments had no documented effect on the outcomes. The European Jewish population lost between approximately 10% and 30% of its pre-1349 numbers across the massacre-affected regions; the subsequent demographic recovery required the subsequent century and a half.

The Konrad treatise remains in the documentary record as evidence that the medical-empirical falsity of the well-poisoning accusation was known and articulated in 14th-century Latin Christian scholarship — without the subsequent capacity to prevent the actions the accusations produced.