He introduces this notion in the epigraph to the essay, taken from Honoré de Balzac's story Sarrasine in which a male protagonist mistakes a castrato for a woman and falls in love with him.
"Vespasian's axiom" is referred to in passing in the Balzac short story Sarrasine in connection with the mysterious origins of the wealth of a Parisian family.
A text can be reversible by avoiding the restrictive devices that Sarrasine suffered from such as strict timelines and exact definitions of events.
•
In his S/Z (1970), Barthes applies this notion in an analysis of a short story by Balzac called Sarrasine.