Aquinas: On Being and Essence - Chapter 5

Chapter Five

ESSENCE AS FOUND IN DIFFERENT BEINGS

[1] From what has been said we can see how essence is found in different things. There are in fact three ways in which substances have essence. There is a reality, God, whose essence is his very being.†1 This explains why we find some philosophers who claim that God does not have a quiddity or essence, because his essence is not other than his being.†2 From this it follows that he is not in a genus, for everything in a genus must have a quiddity in addition to its being. The reason for this is that the quiddity or nature of a genus or species does not differ, as regards the notion of the nature, in the individuals in the genus or species, whereas being is diverse in these different individuals.†3

[2] If we say that God is pure being, we need not fall into the mistake of those who held that God is that universal being by which everything formally exists.†4 The being that is God is such that no addition can be made to it. Because of its purity, therefore, it is being distinct from all other being. That is why the commentary on the Book of Causes says that the first cause, which is pure being, is individuated through its pure goodness.†5 But even though the notion of universal being does not include any addition, it implies no prescinding from an addition. If it did, we could not conceive anything existing in which there would be an addition to being.†6

[3] Furthermore, although God is pure being, it is not necessary that he lack other perfections or excellences. On the contrary, he possesses all the perfections of every kind of thing, so that he is called absolutely perfect, as the Philosopher and Commentator say.†7 In fact, he possesses these perfections in a more excellent way than other things, because in him they are one, whereas in other things they are diversified. This is because all these perfections belong to him in virtue of his simple being.†8 In the same way if someone could produce the operations of all the qualities through one quality alone, in that one quality he would possess every quality.†9 Similarly, God possesses all perfections is his being itself.

[4] Essence is found in a second way in created intellectual substances. Their being is other than their essence, though their essence is without matter. Hence their being is not separate but received, and therefore it is limited and restricted to the capacity of the recipient nature. But their nature or quiddity is separate and not received in matter. That is why the Book of Causes says that the intelligences are unlimited from below and limited from above.†10 They are, in fact, limited as to their being, which they receive from a higher reality, but they are not limited from below, because their forms are not limited to the capacity of a matter that receives them.

[5] That is why among these substances we do not find a multitude of individuals in the same species, as has been said,†11 except in the case of the human soul because of the body to which it is united. And even though the individuation of the soul depends on the body as for the occasion of its beginning, because it acquires its individuated being only in the body of which it is the actuality, it is not necessary that the individuation cease when the body is removed. Because the soul has a separate being, once the soul has acquired its individuated being by having been made the form of a particular body, that being always remains individuated. That is why Avicenna says that the individuation and multiplication of souls depends on the body as regards its beginning but not as regards its end.†12

[6] Furthermore, because the quiddity of these substances is not identical with their being, they can be classified in a category. For this reason they have a genus, species, and difference, though their specific differences are hidden from us.†13 Even in the case of sensible things we do not know their essential differences;†14 we indicate them through the accidental differences that flow from the essential differences, as we refer to a cause through its effect. In this way 'biped' is given as the difference of man. We are ignorant, however, of the proper accidents of immaterial substances; so we can designate their differences neither through themselves nor through accidental differences.

[7] We must observe that the genus and difference are not derived in the same way in these substances and in sensible substances.†15 In sensible substances the genus is obtained from the material side of the thing, whereas the difference is obtained from its formal side. That is why Avicenna says †16 that in substances composed of matter and form, the form is the simple difference of that which is constituted by it; not that the form itself is the difference but that it is the principle of the difference, as he says in his Metaphysics.†17 A difference of this kind is called a simple difference because it is derived from a part of the quiddity of the thing, namely its form. But since immaterial substances are simple quiddities, we cannot take their difference from a part of the quiddity, but from the whole quiddity. As Avicenna says, only those species have a simple difference whose essences are composed of matter and form.†18

[8] The genus of immaterial substances is also obtained from the whole essence, though in a different way. Separate substances are like one another in being immaterial, but they differ in their degree of perfection, depending on their distance from potentiality and their closeness to pure act. Their genus, then, is derived from what follows upon their immateriality, as for example intellectuality, or something of this sort. Their difference, which in fact is unknown to us, is derived from what follows upon their degree of perfection.

[9] These differences need not be accidental because they are determined by degrees of perfection, which do not diversity the species. True, the degree of perfection in receiving the same form does not produce different species, as for example the more white and the less white in participating whiteness of the same nature. But different degrees of perfection in the forms themselves or in the participated natures do produce different species. Nature, for example, advances by degrees from the plant to the animal world using as intermediaries types of things that are between animals and plants, as the Philosopher says.†19 Of course intellectual substances do not always have to be divided by two real differences; as the Philosopher shows, this cannot happen in all cases.†20

[10] In a third way essence is found in substances composed of matter and form. In these, too, being is received and limited, because they have being from another. Their nature or quiddity, moreover, is received in designated matter. Thus they are limited both from above and from below. A multitude of individuals in the same species is also possible in their case because of the division of designated matter. As for the relation of the essence of these substances to logical notions, that has been explained above.†21