This thirteenth volume in the Poincare Seminar Series is devoted to Henri Poincare himself, his manifold contributions to mathematical physics and their continuing importance today. It contains the following chapters: - Olivier Darrigol, Poincare's light; - Alain Chenciner, Poincare and the three-body problem; - Laurent Mazliak, Poincare's odds; - Francois Beguin, Henri Poincare and the uniformisation of Riemann surfaces; - Philippe Worms, Harmony and chaos - on the figure of Henri Poincare. Dating from their origin in lectures to a broad scientific audience these five chapters are of high educational value. This book is of general interest to physicists, mathematicians and historians.