From 1865 to 1869, on a “government order”, Louis Pasteur tackled a silkworm disease, the pebrine, which was ruining the economy of southern France. Well beyond the scientific results—he was going to highlight a second disease, the flacherie—and the operational results—he installed techniques to limit the progression of one disease and protected the farms from the other—, this sequence opened the door to what would become Pasteur’s working method: a science involved in practice, a great importance given to the team of collaborators and to innovations of all kinds, in this case, microphotography. It also establishes the characteristics of the socialization of the Pasteurian approach: diffusion of methods among all the social actors concerned, networking of scientists and internationalization of research.