Definition
An excursus is a detailed discussion or digression within a written work that explores a related, but somewhat separate, topic. It's like taking a scenic detour on a road trip. It provides additional information or context that might not be strictly necessary but adds depth to the main subject. Think of it as a footnote that goes on for several pages. An excursus can be used to clarify a point, offer a counterargument, or simply explore an interesting tangent.