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.
When death, the cessation of life, reveals the underlying spirit, the conscious essence of a being, which can then manifest as a ghost, an apparition of the deceased that appears to the living.
External reference — all senses of the word “ghost” on Wiktionary. This atlas concept maps to only the slice of meaning relevant to the prerequisite graph.