Each concept here is mapped to its prerequisites — the ideas you'd need first to understand it — all the way down to four foundations: Space, Time, Energy, Pattern. Click any prerequisite to drill down, or scroll for the chain graph.
The fourth wall is an imaginary barrier separating the stage from the audience, creating the illusion of a realistic scene by using the concept of a wall in a theatrical context.
External reference — all senses of the word “fourth wall” on Wiktionary. This atlas concept maps to only the slice of meaning relevant to the prerequisite graph.