The myth of inexhaustible African forest resources was constructed at the beginning of the XXth century and lasted for years. It promoted the view of a very rich forest, over vast surfaces, easily renewing itself through strong, spontaneous vegetation dynamics. This exageration comes from a great number of factors that we propose to highlight. If the lack of knowledge of field realities can partially account for the period 1900-1920, the late persistence of such a stereotyped view is the result of a well orchestrated lobbying which is at the origin of great human and financial hardships. The understanding of this gives perspective to the contemporary concern of scientists for the conservation of global forest resources.