The categories then are names signifying things capable of becoming predicates in a proposition.
Primal Life, who is properly speaking the Mandaean god, has the same predicates as the primal spirit, and every prayer, as well as every section of the sacred books, begins by invoking him.
As has been said it classifies universals as predicates of individuals and thus involves the difficulties which gave rise to the controversy between realism and nominalism.
As we advance from the logic to the metaphysics and from that to his ontology, it becomes clear that the concepts are only " categories " or predicates of a reality lying outside of them, and there is an ultimate division between the world as the object or matter of thought and the thinking or moving principle which gives its life.
It follows that Aristotelianism in the Categories and in the Metaphysics is a realism both of individuals and of universals; of individual substances as real subjects, and of universals as real predicates.