  Robert is responsible for one of the first Latin commentaries on Aristotle's Categories since Boethius' Commentary over six centuries earlier, even though his conception of logic is highly influenced by Boethius.  He developed a doctrine of a twofold consideration of categories: categories are considered in one way in logic and they are considered in another way in metaphysics.  This twofold consideration becomes important for subsequent philosophers, such as Aquinas and Scotus, who maintain that in logic, categories have one set of properties, whereas in metaphysics, they have another set of properties.  