An excursus (from Latin excurrere, "to run out of") is a short episode or anecdote in a work of literature (External Link). 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, similar to the role of satyr plays in Greek theatre. Sometimes they are used to provide backstory to the matter being discussed at hand, as in Pseudo-Apollodorus' Bibliotheke. Furthermore, an excursus is often applied to a piece of acade… (More on Excursus)