DE&E: Chapter 1:4

Reverting back, momentarily, to the first paragraph of Chapter 1, recall that Thomas describes two different senses of the word “being”: being as divided into the ten categories, and being as the truth of propositions. “Light” is a being in the first sense, and “Darkness”, being a privation, is a being only in the second sense. It occurred to me that we might refer to the first sort of being as a being proper, and the second sort as a being by courtesy.

Anyway, let us move along to the fourth paragraph of the chapter.

But because being is absolutely and primarily said of substances, and only secondarily and in a certain sense said of accidents, essence too is properly and truly in substances and is in accidents only in a certain way and in a certain sense.

Recall that substance is the first of the ten categories; which implies, now I come to think of it, that the other nine categories are all accidents. So a substance is a being and has an essence in the most proper and true sense, and accidents are beings and have essence only in a certain way and in a certain sense. So where we started with two senses of the word being we now have three: the being of substances, the lesser being of accidents, and the being by courtesy of privations and negations.

I picked up a book the other day by a Dominican friar named McCabe; it’s called On Aquinas. I’ve not read much of it yet, but of the little I have one idea that’s stuck is that Thomas (and Aristotle before him) use many terms in an analogical sense. He speaks of this in the context of souls. The soul of a cockroach is both different and greater than the soul of a plant; the soul of a dog is different and greater than the soul of a cockroach; the soul of a man is different and greater than the soul of a dog. In none of these cases do we mean quite the same thing by “soul”. And yet, what we do mean is similar. The soul of a dog is like the soul of a man but only in a certain way, and in a certain sense.

I see the same thing going on here with words like being and essence. They have a number of greater and lesser senses, all sufficiently similar to warrant using the same term, but all sufficiently different to be a stumbling block to the beginner. Whiteness is the essence of an accident, that of having the color “white”; humanity is the essence of a human person. Both are abstracted from the thing that has them, and become objects of thought, terms that are apprehended by the intellect, and that may be used in propositions. But the sense in which humanity is an essence is different and greater than the sense in which whiteness is an essence.

Lo, what light through yonder window breaks? It is the East, and understanding is the dawn!


Now some substances are simple and some are composite, and essence is in both, though in the simple substances in a truer and more noble way, as these have existence in a nobler way: indeed, the simple substances are the cause of the composite ones, or at least this is true with respect to the first simple substance, which is God. But because the essences of these substances are more hidden from us, we ought to begin with the essences of composite substances, as learning is easier when we begin with the easier things.

Again, it seems counter-intuitive that composites are easier than things that are simple. But we must remember what Thomas means by “simple” and “composite”. A composite substance consists of matter and form, of potency and act. These are two different ways of looking at it, but they are (so I gather) fundamentally equivalent. A substance has potency because it contains matter; it is its form that actualizes it, that gives it act. So simple substances are substances of pure act, with no potency, of pure form, with no matter. Which is to say, angels and other spirits, and above them, the Lord God. But we cannot perceive these simple substances with our senses, and so we cannot apprehend their essences from our sense of them, and so although simpler they are indeed harder for us to grasp.

And so, in Chapter 2, we will begin to look in more detail at the composite substances, like your rose bushes, your dog, and your children.

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