No one familiar with the career of Dr Jacques Benveniste will be at a loss to understand why the company founded to support his research should have marked his death with a press release quoting the great French physiologist Claude Bernard: “When the fact that we come up against does not agree with the predominant theory that we have accepted, we must take the fact and abandon the theory.” The facts that Benveniste claimed to have uncovered altered the course of his life. Whether his change of direction was justified—indeed whether the facts really were as he believed them to be—generated a debate that intrigued biomedical scientists for several months during the late 1980s.

At that time Benveniste was head of allergy and inflammation immunology at the French biomedical research agency INSERM (Institut de la Santé et de la Recherche Médicale). The saga began when a member of his staff put a homoeopathically diluted remedy through an allergy test devised by Benveniste, and obtained …