The discussion centers on the mathematical interpretation of the term "rest" when describing the relationship between two line segments. It highlights that for one segment to "rest on" another, they must coincide at all shared points, which complicates the definition. The term is often better expressed as "is tangent to," particularly in the context of optimization problems where segments may touch at specific points. In three-dimensional space, segments can rest on each other at a single point, but this is less common in two-dimensional contexts. Ultimately, the conversation emphasizes the need for precise language in mathematical descriptions of geometric relationships.