We propose Intrinsic Quality Theory (IQT), a framework identifying phenomenal quality with the intrinsic physical state of bounded spacetime regions. Unlike functionalist theories, IQT treats quality as an identity, not an emergent property of information processing. The theory is formalized using Algebraic Quantum Field Theory (AQFT) on causal sets, defining a region’s quality as the local algebra–state pair, up to physically induced isomorphism. A constraint-based argument shows this pair is the unique mathematical object satisfying the requirements any candidate for “intrinsic nature” must meet. Central commitments include the perspectival relativity of quality (no privileged “view from nowhere”) and an effective-theory framework bridging fundamental and neural scales. The geometry of effective causal diamonds generates temporal phenomenology — including the asymmetry between panoramic spatial and fleeting temporal experience — without additional postulates. The theory dissolves the subject-selection debate by separating universal quality from narrative selfhood, and provides a non-ad-hoc mechanism for composition of experience grounded in correlation structure. The paper presents three concrete empirical protocols (titrated propofol anesthesia, within-hemisphere parcellation, psychedelic temporal phenomenology) that generate distinct predictions separating IQT from Integrated Information Theory and Global Neuronal Workspace theory.