What is the main conflict in A Life in the Theatre by David Mamet?

The two-character drama/comedy has hallmarks of Mamet's later work: intense characters; taut, revealing dialogue; and a mentor/teacher relationship. Describing life in the footlights from an actor's point of view, A Life in the Theatre focuses on the relationship between two thespians: Robert, an older, experienced performer; and John, a relative newcomer. Though Robert's guidance is welcomed by John at first, as the play progresses Robert falters as an actor and mentor, and John emerges as a mature actor.