Item from Foundation by Isaac Asimov
A chamber on Terminus where a holographic Hari Seldon appears at each predicted crisis point. He cannot answer questions — he recorded his messages centuries ago. He is always right.
The Seldon Vault is psychohistory made personal. At each predicted crisis — the moments when the Foundation's survival hangs in the balance and only one course of action leads to the plan's continuation — the vault activates and Seldon's hologram explains what just happened, why it happened, and what the Foundation should do next. He is always right because the crises themselves were predicted, and the explanations were written with full foreknowledge of the circumstances. The effect on the Foundation's population is complex. In early crises, Seldon's appearances are galvanizing — proof that the plan works, that their sacrifices have meaning, that someone saw this coming and prepared. In later crises, the vault becomes oppressive. Seldon's certainty implies that free will is an illusion, that every struggle and sacrifice was predetermined, that the Foundation's heroes are characters in a script written by a dead mathematician. When the Mule conquered Terminus, the vault activated and Seldon's hologram described a crisis that wasn't happening — proof that the plan had derailed. This was the most important vault appearance in the series because it confirmed that psychohistory had limits and that the Foundation would need to save itself without a script for the first time.
A nondescript building in Terminus City's old quarter — deliberately unprepossessing, its entrance unmarked. Inside, a single large chamber with curved walls and a raised platform at the center. When activated, the platform generates a life-sized holographic projection of Hari Seldon as he appeared in old age: white-haired, sharp-eyed, seated in a simple chair. The hologram speaks for precisely as long as Seldon recorded, then vanishes. The chamber's acoustics are tuned for a single voice addressing a crowd. There are no other furnishings.
Also known as: the Vault, the Time Vault, Seldon's Vault