<jats:p>Aristotles Categories are still widely seen as being incompatible with both Aristotles later analysis of ousia (in Metaphysics Z) and Platos ontology. Rainer Thiel shows that the Neoplatonic commentaries on the Categories that go back to Porphyrys reading can be viewed as a valid interpretation of Aristotle which does not contradict Plotinus view, but in fact can be traced back to him.</jats:p>