How does my brain work? Why am I conscious? Where is my memory? Is what I perceive around me reality or just an illusion? We all ask these questions, which we could sum up in a single question: Who am I? How is it that I have memories and that I feel I exist? What does it mean that my mind is free in time and space, and yet I am imprisoned in a body that is doomed to disappear? What happens to my mind when my body disappears? What are the risks of my suffering from a brain disease? Could my whole being eclipse because of a disease in which my body survives but my mind ceases to exist? What remedies are there? What hope does reasearch hold out? Recent discoveries about the brain allow us to ask such questions more pointedly, hoping to define more clearly the relations of the brain with the mind, of man with his body. This book is based on numerous discussions with specialists. It attempts to determine the state of the art. It is organized in chapters that can be read in continuity, but it is equally possible to discover the chapters in a different way.