Property and Accident, compare and contrast:
It remains to speak of property and accident, for how property differs from species, difference, and genus, has been stated. It is common then to property and inseparable accident not to subsist without those things in which they are beheld, for as man does not subsist without risible, so neither can Ethiopian subsist without blackness, and as property is present to every, and always, so also is inseparable accident. Nevertheless, they differ, in that property is present to one species alone, as the being risible to man, but inseparable accident, as black, is present not only to an Ethiopian, but also to a crow, to a coal, to ebony, and to certain other things. Moreover, property is reciprocally predicated of that of which it is the property, and is equally (present), but inseparable accident is not reciprocally predicated, besides, the participation of properties is equal, but of accidents one (subject partakes) more, but another less. There are indeed other points of community, and peculiarity of the above-mentioned (predicables), but these are sufficient for their distinction, and the setting forth of their agreement.
There’s nothing really new here; all of these points have been made previously. What it comes down to is this: a property is a necessary consequence of the essence of the thing, and applies only to that species, and is always present, whereas accidents, even inseparable accidents, can be more or less present, and are not a necessary consequence of the essence of the thing.
Now, Porphyry says that a property is a property of one species alone. And yet some species are genera in their own right. In Porphyry’s scheme, for example, man is a genus within which divinity is a species: the gods are immortal men. And surely these gods, being rational, would also be able to laugh. So to say that a property is a property of one species alone is true, but misleading: it is predicated of all individuals that belong to that species, whether directly of through some subspecies.
Anyway, that’s it; we’re done with Porphyry! And there was great rejoicing!