Identity is not material persistence but boundary-structured flow. Through the Theory of Axiomatic Necessity (TNA) and the fluid dynamics analogy of a riverbed, this paper formalizes the soul as a non-derivable N1 structure persisting through complete material turnover. Using the Manning formula for open-channel flow as a formal bridge, we demonstrate that the hydraulic radius encapsulates boundary conditions that determine flow behavior without being reducible to the fluid (N₀) itself. This framework identifies the fine-tuned constants of the cosmos, the genetic code, morphogenetic fields, and species boundaries as nested N₁ structures—non-derivable, non-Lipschitz boundary conditions that select realizable trajectories and exclude unstable ones. We address the genomic adaptations of Chernobyl wolves as a case of dynamic boundary reconfiguration. Ultimately, we demonstrate that the soul is precisely understood as N₁: the identity-constituting boundary structure that remains persistent across continuous atomic replacement, showing structural convergence with Aristotelian hylomorphism, Thomistic anima, Whiteheadian process, and Buddhist anatta.
Claudio Bresciano (Wed,) studied this question.