This work formulates a fundamental theorem establishing that gravity is neither an interaction nor a curvature of geometry, but a direct manifestation of the identity of space and time through the gradient of the local temporal rate. The theorem unifies ontology, metric geometry, classical mechanics, and quantum field theory into a single axiomatic system. Ten corollaries are proposed, covering the nature of inertial and gravitational mass, the stability of matter, the strength of materials, the mechanism of antigravity, the role of massless particles in the formation of the field, the relational nature of gravity, as well as the temporal interpretation of the periodic table, the essence of life, and death. The work offers a new perspective on the origin of mass, energy, and the space-time continuum. The legal status of the theorem as an objective law of nature, open to fundamental science, is established. Note of the second edition: In this version (dated July 21, 2026), a sign error in the Poisson equation has been corrected, and the proof of the theorem has been rewritten in accordance with the author's approach, where the emphasis is placed on conceptual rather than formal mathematical rigor.