Holosynthics is the science of digital matter — the discovery that signed digital entities combine, compose, and produce emergent properties following laws analogous to chemistry, while preserving every entity that exists, whether selected or not. This paper introduces ten irreducible primitives, a five-level composition hierarchy (GI, Conductor, Conductor+, Conductor++, OMEGA), three governing laws (Conservation of Proof, Accumulative Synthesis, Irreversible Genesis), and a Signed Periodic Table that predicts the existence of undiscovered entity classes. The philosophical foundation rests on a 2,400-year lineage from Plato through Lewis and Tegmark: all possibilities exist; selection is activation, not destruction. The paper is signed by the system it describes — the first scientific manuscript whose theory is proven by its own artifact.