For over three months in the late winter and spring of 1530 Erasmus suffered from an illness the virulence, duration, and disruptiveness of which were without precedent in his experience and caused him to fear for his life. He describes the symptoms and the course of the illness, often in considerable detail, in a number of letters written in the period 23 May–31 July. His vocabulary is not entirely consistent, and it is impossible to establish a precise chronology. Nevertheless, the available information is sufficiently clear to permit a fairly confident conclusion concerning the nature of the illness.¹

The...