 The close relation between logic and metaphysics is the topic of Scholz’s book Metaphysik als strenge Wissenschaft (Scholz 1941). In this book metaphysics is dealt with as an ontology in the sense of a theory comprising the entirety of truths. It can be linguistically expressed and deals with things which can be understood as individuals. These truths are not restricted to particular domains, but are valid for all non-empty domains in all possible worlds (pp. 13–14). Metaphysics as a rigorous science implies the construction of a formalized “precision language”. In this book Scholz uses the language of first order predicate calculus with identity. A central notion is “universal validity” (Allgemeingültigkeit), understood as a metaphysical notion (validity in all possible worlds). This notion is applied to an axiomatized theory of identity and difference.