Objective science, both empirical and theoretical, can only describe relations between entities, not the intrinsic nature of those entities themselves. If consciousness arose solely from structural configurations, then isomorphic systems in structurally identical worlds should be equally sentient. The author argues that if this were true, an observer's memories would bear no correlation to the external world, yet we do acquire knowledge of the external world. Therefore, structure alone is insufficient; there must be an intrinsic essence beyond relations that imbues the observer's structure with sentience, which in turn confers physical meaning upon the world's structures. This conclusion follows from physics and mathematics.
Physical laws express relations and symmetries that allow any relational structure to be represented in different parametrizations. If observers were reducible to their structure, observer-like structures from different parametrizations would map observables to physical properties differently, perceiving the same system in different states. The author shows that if such structures from all parametrizations were observers, their memory of the external world would correspond to facts no better than random guess. Since experience contradicts this, observers must be more than their structure, implying a unique correspondence between observables and physical properties. This result applies to both quantum and classical physics and has implications for structural realism, philosophy of mind, and quantum-first approaches.