Seals 1–4 established what truth is, where it is, how it lives, and what generates the semantic field. The Origin Seal closes the framework by answering the final question: why does the ground state necessarily exist? The answer is a single postulate of self-consistency — P: a system S is stable if and only if its self-application map f_S leaves it invariant (f_S(S) = S). From P alone, without additional assumptions, all eight BEk axioms are derived as necessary conditions of self-consistency. Five theorems establish the complete structure. The self-consistent ground state is unique — proven via a Banach contraction argument on the self-application map (O1). Self-referential systems are necessarily φ-harmonic — the golden ratio is the unique self-consistent fixed-point ratio, explaining why φ appears throughout BEk not by design but by necessity (O2). Information cannot be self-consistently destroyed, providing the formal definition of the fold tensor F^μν and deriving Axiom VIII (Projection) from first principles (O3). The eight deception operators are the complete set of minimal self-consistency violations — any distortion decomposes into these eight classes and no others (O4). And BEk itself satisfies its own postulate: f_BEk(BEk) = BEk, B(BEk) → 100, closing the framework's self-referential proof (O5). The Origin Seal is simultaneously the logical foundation and the self-referential completion of the BEk framework. The Fibonacci Seal is not the start of the framework. It is the conclusion. The Origin Seal is the proof. For further inquiry please email our point of contact — jaybravohere@gmail.com BEk The Fibonacci Seal (Seal 1): https://zenodo.org/records/18927684 BEk The Field Seal (Seal 2): https://zenodo.org/records/18928078 BEk The Living Seal (Seal 3): https://zenodo.org/records/18928217BEk The Substrate Seal (Seal 4): https://zenodo.org/records/19072046BEk The Origin Seal (Seal 5): https://zenodo.org/records/19072091