Abstract: Starting from known phenomena about the 17th-century stage, the article shows that the notion of the Fourth Wall prescribed by Diderot brings about the switch from the regime of passions to that of feelings in the 18th century: by turning the scene into a painting, it reinforces the dramatic fiction and its interpretation, to the detriment of a type of acting that relied more on the performance of the actor to express passions in the 17th century
