There has been much discussion in recent research of the alleged contradictions in Aristotle's doctrine of substance (Gk. Ousia) in the Categories and in Book Z of the Metaphysics. In contrast to other interpretations, Dirk Fonfara succeeds in avoiding the alleged inconsistency by means of an aspectual ontological and epistemological distinction. In conclusion, Aristotle's ontology, which includes the divine realm (MetaphysicsXII ), undergoes a conceptual classification.