“Blood: you’ve never heard of it before” - if the phrase weren’t so hackneyed, it would be suitable for the title of this book, since it fully reveals the authors’ intentions. Blood is the life within us. She talks about our heredity, health, lifestyle, about us as a biological species. It is a social network through which organs communicate. This liquid has various meanings and is used in rituals, fine arts and cooking. Diseases and scandals are associated with it. Discover your own inland sea. The authors, specialists in hematology, talk about blood, citing both the latest research data and stories from medical practice. Olivier Garraud is an immunologist and hematologist, professor at the Faculty of Medicine at the University of Saint-Etienne, where he, among other things, , teaches medical ethics. Jean-Daniel Tissot is a physician, hematologist, specialist in laboratory medicine, professor at the Faculty of Biology and Medicine at the University of Lausanne, where he served as dean from 2015 to 2021.