An excursus (from Latin excurrere, 'to run out of') is a short episode or anecdote in a work of literature.
[1] Often excursuses have nothing to do with the matter being discussed by the work, and are used to lighten the atmosphere in a tragic story, a similar function to that of satyr plays in Greek theatre.
In the Middle Ages, the excursus is a favourite rhetorical device to allow the narrator to comment or to suspend the action for reflection.
[2] Furthermore, an excursus is often applied to a piece of academic writing to provide digressive information, which does not contribute directly to the line of argument but can still be linked with the overall topic of the text.
The most famous case of etymologies being used as excursuses is in the Golden Legend (ca.