Chapter 12

Difference and quality and property are all the same thing in relation to their subject, but in relation to their operation they are different. Thus, rationality is said to be both a quality and a property and a difference of man, but it is these, in different ways. Thus, on the one hand, in so far as it makes and, as it were, forms the substance, it is said to be a quality. Then, in so far as it becomes peculiar to this substance, it is said to be a property. But, in comparison with the irrational—an ox, say, or a mule, or a dog—then it is said to be a difference, because in it man diffe