1This book is a set of papers from a conference held in 2013 at France’s National Academy of Medicine; the aim was to better apprehend the many facets of a curious man, the Academician Charles Richet, awarded the Nobel Prize in Physiology or Medicine in 1913 for his discovery of anaphylaxis. While Richet was chosen for his major contributions to immunology, the contributors are careful not to overlook either the originality or contradictions of the man: a pioneer in aviation, a specialist of somnambulism, a staunch eugenicist, a scholar but also a litterateur, a positivist but also a believer in metempsychosis and the racist ideas of his time. Studying his trajectory, his failures, his “non-contributions” and self-contradictions is a means of reflecting more generally here on the complex nature of the knowledge and prejudices of his time. Charles Richet was undeniably curious, but Raymond Ardaillou shows how little he knew of contemporaneous scientific advances, particularly in statistics, and how inattentive he was to innovative research by such important scholars and scientists of his time as Darwin and Gregor Mendel. As an eminent physician and physiologist, Richet’s embracing of eugenics makes him a particularly interesting subject for demographers and population historians. Strongly influenced by Francis Galton’s writings on heredity and open to radical policies, Richet developed a variety of eugenics based on the exclusion of “unfit” individuals – i.e., so-called “negative” eugenics – but also a positive variety, more marginal in France, aimed at improving the “race” through hygiene and education measures – a fact that echoes Paul-André Rosental’s findings in a recently published work reassessing the supposed marginality of such positions. [1] Anne Carol stresses the originality of this unusual personality: the constancy with which he defended his convictions, even after World War I, when the “demographic hemorrhage” had led other French eugenicists to tone down their discourse given the threat of depopulation. In sum, a highly paradoxical trajectory that the contributors are at pains to account for.