One axiom. One operation. Zero free parameters. Memory is the persistence of a pattern through time in a substrate that constantly turns over. How does something stay the same while its material changes? This paper gives the fold’s answer. A memory is a held orbit — a fold cycle that perpetually folds into itself. The simplest case is 1/3 ↔ 2/3: under the fold each state maps to the other forever, and the two sum to the One. The pattern persists not by sitting still but by circulating — each state regenerated from the other every fold — so it survives a substrate in flux. And the persistence is structural: an odd-denominator orbit is eternal (never decays), while an orbit whose denominator carries a factor of two is transient (decays away). A memory lasts exactly when held as an eternal odd orbit; forgetting is the orbit going transient. Memory is a self-sustaining loop, permanent because an odd cycle is eternal. Machine-checked; reproduces from one command. A standalone result within the Smithian Fold Theory of Everything (SFTOE). Full corpus, code, and the run-it-yourself VERIFY.md protocol: https://github.com/MettaMazza/Smithian-Fold-Theory
Maria Smith (Mon,) studied this question.
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