The seed must survive the fall. The Vault does not hoard — it encodes, spreading each truth across enough copies that corruption can eat some and the whole still returns. Below the threshold it heals perfectly; one error past it, and the record is lost.
Each bit is stored as an odd number r of copies and recovered by majority vote — a repetition code that provably corrects up to ⌊r/2⌋ errors per bit and fails at ⌊r/2⌋+1. The instrument corrupts random copies at the chosen rate, runs the majority decode, and reports which bits healed and which were lost — the exact threshold behaviour of error-correcting storage, verified against the code's stated correction bound.
'The Vault', 'surviving the fall' is Asimov's Time Vault. The real object is a repetition error-correcting code and majority-vote decoding — genuine, if the simplest, ECC. Real archives use stronger codes (Reed–Solomon); the threshold idea is the same.