 A theory is empirically adequate, then, if appearances—“the structures which can be described in experimental and measurement reports” (1980, 64)—are isomorphic to the empirical substructures of some model of the theory. Roughly speaking, the theory is empirically adequate if the observable phenomena can “find a home” within the structures described by the theory—that is to say, the observable phenomena can be “embedded” in the theory. See Figure 1 for a graphical illustration of the relations that make a theory empirically adequate on van Fraassen’s view, with the cloud shapes representing the relata of the isomorphism relation.