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.
A hidden door or passage, often used in stagecraft for dramatic effect, emerges from the need to create a controlled passage between spaces within a constructed environment.
External reference — all senses of the word “trap door” on Wiktionary. This atlas concept maps to only the slice of meaning relevant to the prerequisite graph.