William James Sidis’s 1925 work The Animate and the Inanimate introduced athermodynamically inspired division of the universe into two regions: one obeyingthe conventional second law of thermodynamics (the inanimate) and another whereentropy locally decreases (the animate). Although historically misunderstood anddismissed as speculative philosophy, his framework can be formalized in modernmathematical physics and shown to have conceptual parallels with contemporarytheories in non-equilibrium thermodynamics, information theory, and cosmology.This paper provides a purely mathematical formulation of Sidis’s idea, demon-strates why it is not inherently incompatible with modern physics, and argues forits reconsideration, with worked examples and diagrams connecting his concepts tomodern theory.