Augustus Lane Fox Pitt-Rivers (1827-1900) and Édouard Piette (1827-1906) both donated their collections to a museum, submitting their donations to the same strict conditions, in particular concerning the presentation of the objects. They did so because, in both cases, they considered their collections as demonstration tools for their scientific theories. Based on an analysis of the shapes of the objects in his ethnographic collection, Pitt-Rivers proposed a real philosophy of progress: the mental calculations and the shapes that resulted follow the same laws of evolution as those of living organisms. The main goal of geologist and pre-historian Édouard Piette was to establish a chronological synthesis of prehistory based on the juxtaposition of industrial assemblies. We examine these theories, the way the museum displays were conceived and what remains today.