Differentiation and singularity of style are considered, over the long run, to be a revolution better understood by taking into account the global changes of a literary space in which other concomitant mutations take place : the biographical marking of literature, the anointing of the writer, the autonomous empowerment of literature, the questioning of genre and form, and so forth. Thus it is a question of considering Buffon’s remark through a historical lens. This study follows the different phases of the differentiation and singularity of style, from the Encyclopedia up to Hugo’s William Shakespeare, and includes Marmontel, Mercier, Mme de Staël, and the theoreticians of the Second Cenacle. This study will show that, after 1830, this differentiation and singularity are seconded by a more technical consideration of the formal variables that constitute an author’s style, but also by a critique of stylistic idiosyncrasies that are too systematic.