van Helmont's proposal for a randomised comparison of treating fevers with or without bloodletting and purging.

Around the year 1643, Joan Baptista van Helmont, a Flemish chemist, alchemist and physician who had devised what he claimed to be a new form of medicine, proposed a 'challenge' to traditional Galenic physicians to compare treatment of fever by traditional methods and by a regime which did not involve bloodletting and purging. Two groups of patients were to be treated and 'casting of lots' was to be used - in some way not specified in detail - to decide who received which treatment. This 'challenge' has been regarded as the first proposal for the use of randomisation in a clinical trial. This paper explains the background to the challenge and discusses what can be deduced from Helmont's text about the details of how he proposed that the 'trial' was to be carried out. It concludes that internal evidence in Helmont's writings makes it certain that no such 'trial' was ever conducted. It seems that the 'challenge' was probably a rhetorical device to support Helmont's vehement criticism of traditional Galenic medicine and its practitioners, and, in particular, toemphasise his absolute opposition to the use of bloodletting as a medicaltreatment. An appendix includes a short summary of Helmont's theories of the origins of disease and transcriptions of the passages of Helmont's Latin text translated in the article.