Does it make sense to place hallucinogens and hard drugs in the same category and to regard them all as addictive? Should tobacco and alcohol be put on the same plane as heroin, cocaine and crack ? With the assistance of Carlos Parada, his collaborator at the Centre Médical de Marmottan, Claude Olievenstein offers the reader his latest thoughts and ideas on the highly distinctive world of substance abusers, which is characterised by pleasure, withdrawal, the need for warmth and haste and, above all, by instability and chaos. Claude Olievenstein is the head doctor at the Centre Médical de Marmottan, in Paris, and a senior research fellow at the University of Lyon-II. Carlos Parada, a physician specialising in drug addiction, works at the Centre Médical de Marmottan.