DE&E: Chapter 5:7

Continuing yesterday’s thought on the nature of genus an difference for immaterial substances, Thomas says:

Similarly, in immaterial things the genus is taken from the whole essence, though not in the same way as the difference is. One separated substance is like another with respect to their immateriality, but they differ one from another with respect to their grade of perfection according to how far each recedes from potentiality and approaches pure act.

Right, we’ve been through that.

And so, in such substances, the genus is taken from that which arises in these substances insofar as they are immaterial, as intellectuality and such things; the difference, however, is taken from that which arises in these substances from their grade of perfection, although these differences are unknown to us.

How do they differ? In terms of how perfect they are, how much in act and how much in potency. Their genus, I gather, depends on their properties, i.e., all immaterial substances are, apparently, intellectual, but some may have properties others do not, and this would lead to distinct genera.

Nor are these differences accidental because they arise from greater and lesser perfection, which do not diversify the species. For, while the grade of perfection in receiving the same form does not diversify the species (as whiter and less white in participating in whiteness of the same type),….

My son and I belong to the same species. Presumably, as he’s 11 and I’m, ahem, rather older than that, I’ve more act and less potency than he does when it comes to being a man. We both participate in the same form to a lesser or greater degree, and that does not make us different species. But immaterial substances are different.

….nevertheless, a different grade of perfection in these participated forms or natures does diversify the species, just as nature proceeds by grades from plants to animals through those things that are median between plants and animals, as the Philosopher says in VIII De Historia Animalium cap. 1 (588b4-12).

I take this to mean that there needs to be a qualitative difference in the degree of perfection, not merely a quantitative difference. (I’m sure that the terms “qualitative” and “quantitative” aren’t exactly right, here, but you get the idea.)

Nor is it necessary that the division of intellectual substances always be made through two true differences, for it is impossible that this happen in all things, as the Philosopher says in I De Partibus Animalium cap. 2 (642b5-7).

OK, this is completely opaque. I’m not sure how much it matters, but it’s completely opaque.

Comments are closed.