Pierre Denis is almost forgotten. It is pity, since he exploited in an original way the precepts of Vidal de la Blache: as his master, he was sensitive to the weight of natural constraints on human behaviour, but stressed mainly the role of techniques of production and exchange in overpassing these obstacles. As a result the interpretation of human geography he proposed was a dynamic one, as shown by his studies on Latin America, Brazil and Argentina. Unfortunately, he renounced early to geographical research.