The categories of possible both worlds and substances should be unified. The base of that unification can be the concept of possible histories (by the way utilized already in quantum mechanics in order to interpret it as “consistent histories”). Futhermore, one can attempt to describe the set of possible histories metaphysically as a general history of how possible substances as initial elements become gradually, stage by stage different possible worlds clearly distinguishable from each other and therefore disjunctive to each other as different realities.