The often stormy public debates surrounding medically assisted procreation illustrate the difficulties society has in accepting that sterility is an illness and that medically assisted procreation should be regarded as a form of treatment. Ancient taboos have resurfaced and sometimes even been rekindled, while moralisers have put pressure to bear. Old beliefs are far from having been overturned.This is hardly unexpected. Throughout history, relations between the irrational on one hand and scientific and medical knowledge on the other and have been particularly ambiguous. Unravelling them would seem to be a major challenge – yet this is what Claude Humeau has set out to do in this book, which traces the evolution of official knowledge and the knowledge held by philosophers, naturalists, biologists and doctors, who have never ceased trying to understand the questions surrounding reproduction. How does sexual reproduction function? How is gender determined? How can failures and mistakes be explained? At the same time as scientists were trying to find answers to these questions, the techniques for mastering reproduction were evolving. As has generally been the case in medical history, practical techniques have preceded the certainties of theoretical knowledge. The irrational, too, has played its part, sometimes slowing down or complicating the development of scientific knowledge. Although it may now be easier to unravel the irrational from the scientific, the fact remains that they still coexist. It could even be said that the increasingly rapid development of biology and medicine has not altered in the least the burden of irrational beliefs that have accumulated over the centuries.This book traces the long history of human knowledge about reproduction. It shows that attempts to master reproduction and to find ways of treating infertility have been constant preoccupations throughout history. It follows the complex relations between scientific knowledge and the irrational, while demonstrating that the conflict between science and fantasy is far from being resolved.Claude Humeau teaches at the medical school of the University of Montepellier, France, and heads the laboratory of reproductive biology at the University Hospital of Montpellier. He is the co-author (with Françoise Arnal) of Médecines de Procréation, published by Editions Odile Jacob.