Antisemitism, Islamophobia and the Conspiracy Theory of Medical Murder in Early Modern Spain and Portugal

In his antisemitic diatribe entitled Breve discurso contra a heretica perfidia do judaismo, first printed in Lisbon in 1622, the Portuguese author Vicente da Costa Mattos railed against many secret conspiracies. He believed that these conspiracies were being orchestrated by the descendants of Jews—generically known as ‘New Christians’—to achieve the complete destruction of both the Catholic Church and the Iberian monarchies of Spain and Portugal. One of the most striking claims made in the Breve discurso is that the allegedly false converts were systematically infiltrating the medical professions to be able to murder genuine Catholics not descended from Jews—so-called Old Christians—and particularly to assassinate high-status individuals in both the ecclesiastical hierarchy and the secular aristocracy. Vicente da Costa Mattos’ strident warning about the evil deeds of secret Jewish serial-killer doctors was no innovation on his part. The fear of Jewish doctors was widely shared in medieval and early modern Europe and was a recurrent theme in anti-Jewish and antisemitic polemics and propaganda. In the early modern Iberian context, however, the fear of medical murder by doctors from marginalised religious communities acquired a new and sinister dimension.