According to stylisticians, transition from the Belles-lettres to littérature during the 19th century is characterised by the abandonment of the rhetorical model in favour of a new langue littéraire, placing the author more at the centre. We try to operationalise this theory, by measuring the pressure exerted by two opposing forces: (i) that of respecting the rules of the genre on the one hand, (ii) and that of the personal signature of the author on the other.