 We should also distinguish between the fundamentality of entities belonging to a certain ontological category and the fundamentality of the ontological category itself. It is one thing to say that certain properties are fundamental; another to say that the category property is a fundamental category. We are mostly concerned with the former issue, but the debate about which ontological categories are fundamental and how many such categories there are has been lively throughout the history of Western philosophy. For instance, Aristotle may have thought that substances are the only category that is separate from and hence more fundamental than other categories, such as the category universals (Aristotle Physics 185a31–32; Metaphysics  1029a27–28).[2]