Such a theory would obviously be priceless for judging and constructing more specific physical theories. When we understand language as a hierarchical model of reality, i.e. a device which produces predictions, and not as a true static picture of the world, metaphysics is understood as much more valuable than just the "free fantasy" of philosophers. To say that the real nature of the world is a certain way means to propose the construction of a model of the world along those lines. Metaphysics creates a linguistic model (logical or conceptual structure) to serve as a basis for further refinements. Even though a mature physical theory fastidiously distinguishes itself from metaphysics by formalizing its basic notions and introducing verifiable criteria, metaphysics, in a very important sense, is physics.