The concept of didactic transposition (Chevallard, 1985) comprehends the process by which savoirs, in the large French sense also meant by the Comenian scire (Wissen/Können), is transformed into savoirs to be taught and savoirs really taught. By this process, savoirs in their praxeological sense are transformed following several regularities and enriched in function of the specific needs of teaching and of the aims of the social institutions designed for teaching and scholarly learning. Didactic transposition in this sense is constitutive for teaching. Our contribution will show in a first part the wide use of the concept in different disciplinary didactiques. In a second part we will analyze two examples of didactic transposition in French literature teaching: one illustrating savoirs to be taught, another one illustrating savoirs actually taught. By these examples, we will show some regularities of the transposition process. We will conclude in suggesting that in disciplines like French as a first language (similar observations could be made for instance on history) the transposition process itself acts back on the definition of what is socially considered as literature, or writing, etc. The concept of transposition has to take into account this loop sometimes called “countertransposition”.