 The other side of the coin of each “price to pay” is the lesson we might gather from the empirical success of quantum theory: for the Many Worlds interpretation, for instance, the lesson is the real existence of other branches, for Bohm theory is the real existence of unobservable variables that pick a preferred reference frame, and so on. For RQM, the lesson of quantum theory is that the description of the way distinct physical systems affect each other when they interact (and not the way physical systems ‘are’) exhausts all that can be said about the physical world. The physical world must be described as a net of interacting components, where there is no meaning to ‘the state of an isolated system’, or the value of the variables of an isolated system. The state of a physical system is the net of the relations it entertains with the surrounding systems. The physical structure of the world is identified as this net of relationships. The notion of substance that plays a major role in western philosophy might be inappropriate to account for this science; perhaps the idea of a “mutual dependency” [Nāgārjuna 1995] may offer a relevant philosophical cadre.