De ente et essentia

Now it remains to see in what manner essence is found in separate substances, namely, in the soul, intelligence, and first cause. Although everyone concedes the simplicity of the first cause, nevertheless some endeavor to introduce a composition of form and matter into intelligences and into the soul; the author of this position seems to have been Avicenna, the author of the book The Fountain of Life. But this conflicts generally with what the philosophers say, because they call these substances separate from matter and prove them to exist without any matter. Their strongest demonstration comes from the power of understanding which is in them. For we see that forms are not actually intelligible except insofar as they are separated from matter and its conditions, nor are they made actually intelligible except through the power of an understanding substance, insofar as they are received in it and insofar as they are acted upon by it. Hence it must be that in every understanding substance there is complete immunity from matter, so that it neither has matter as a part of itself nor is like a form impressed in matter, as material forms are.

Nor can someone say that matter in general does not impede intelligibility, but only bodily matter. For if this were so merely by reason of bodily matter, since matter is called bodily only insofar as it stands under a bodily form, then matter would have to derive this—namely, its impeding intelligibility—from bodily form; and this cannot be, because bodily form itself is actually intelligible, just like other forms, insofar as it is abstracted from matter. Hence in the soul or in intelligence there is in no way a composition of matter and form, so that essence is understood in them in the way it is in bodily substances. Rather, there is a composition of form and being; hence in the commentary on the ninth proposition of The Book of Causes it is said that intelligence has form and being, where “form” is taken for quiddity itself or a simple nature.

And how this is so is clear to see. Whatever are related to one another in such a way that one is the cause of the being of the other, that which has the character of a cause can exist without the other, but not conversely. Such a relation is found between matter and form: form gives being to matter, and therefore it is impossible for matter to exist without some form; yet it is not impossible for some form to exist without matter, for form, insofar as it is form, does not depend on matter. But if some forms are found that cannot exist except in matter, this happens to them insofar as they are distant from the first principle, which is first and pure act. Hence those forms that are closest to the first principle are forms subsisting in themselves without matter; for form does not need matter according to its whole genus, as was said. Such forms are intelligences, and therefore the essences or quiddities of these substances need be nothing other than the forms themselves.

Thus the essence of a composite substance differs from that of a simple substance in this: the essence of a composite substance is not form alone, but embraces form and matter, whereas the essence of a simple substance is form alone. From this arise two further differences. One is that the essence of a composite substance can be signified as a whole or as a part, which occurs because of the designation of matter, as was said. Therefore the essence of a composite thing is not predicated of the composite thing in every way: for it cannot be said that a man is his own quiddity. But the essence of a simple thing, which is its form, can be signified only as a whole, since there is nothing there besides the form, as something receiving the form; and therefore, however the essence of a simple substance is taken, it is predicated of it. Hence Avicenna says that “the quiddity of the simple is something else receiving it.”

The second difference is that the essences of composite things, because they are received in designated matter, are multiplied according to the division of that matter; hence it happens that some things are the same in species and different in number. But since the essence of the simple is not received in matter, such multiplication cannot occur there; and therefore there must not be found in those substances several individuals of the same species. Rather, as Avicenna expressly says, however many individuals there are, so many species there are.

Therefore, although such substances are forms alone without matter, there is not in them complete simplicity, nor are they pure act; rather, they have a mixture of potency. This is clear as follows. Whatever does not belong to the intelligibility of an essence or quiddity is something added from outside and makes a composition with the essence, because no essence can be understood without those things which are its parts. But every essence or quiddity can be understood without anything being understood about its being: for I can understand what man or phoenix is and yet be ignorant whether it exists in nature; therefore it is clear that being is other than essence or quiddity. Unless perhaps there is some thing whose quiddity is its very being; and this thing can be only one and first. For the multiplication of anything is impossible except through the addition of some difference, as the nature of a genus is multiplied into species; or through a form being received in diverse matters, as the nature of a species is multiplied in diverse individuals; or through one being absolute and another being received in something, as if there were a separated heat, it would be other than non-separated heat by its very separation. But if there is posited some thing that is being alone, so that being itself is subsisting, this being cannot receive the addition of a difference, because it would no longer be being alone but being plus some form; still less could it receive the addition of matter, because it would then be being that is not subsisting but material. Hence it remains that such a thing, which is its own being, can be only one. Therefore in every other thing besides it, its being must be other than its quiddity or nature or form. Hence in intelligences there must be being in addition to form, and therefore it was said that intelligence is form and being.

Whatever belongs to something either is caused by the principles of its nature, as risibility in man, or comes from some extrinsic principle, as light in the air through the influence of the sun. But it cannot be that being itself is caused by the form or quiddity of a thing, I mean as by an efficient cause, because then something would be the cause of itself and would produce itself in being, which is impossible. Therefore every such thing whose being is other than its nature must have being from another. And because everything that exists through another is reduced to that which exists through itself as to a first cause, there must be some thing that is the cause of being for all things, because it is being alone; otherwise there would be an infinite regress in causes, since every thing that is not being alone has a cause of its being, as was said. It is therefore clear that intelligence is form and being, and that it has being from the first being, which is being alone; and this is the first cause, which is God.

Now whatever receives something from another is in potency with respect to it, and that which is received in it is its act. Therefore the quiddity or form itself which is intelligence is in potency with respect to the being it receives from God, and that received being is present as act. Thus potency and act are found in intelligences, though form and matter are found there only equivocally. Hence also undergoing, receiving, being a subject, and all such things which seem to belong to things by reason of matter belong equivocally to intellectual substances and bodily substances, as the Commentator says in III On the Soul. And because, as was said, the quiddity of intelligence is intelligence itself, its quiddity or essence is that which it is itself, while its being, received from God, is that by which it subsists in the natural order. For this reason some say that such substances are composed of “that by which it is” and “what it is,” or of “what it is” and being, as Boethius says.

And because potency and act are posited in intelligences, it will not be difficult to find a multitude of intelligences, which would be impossible if there were no potency in them. Hence the Commentator says in III On the Soul that if the nature of the possible intellect were unknown, we could not find multitude in separate substances. Their distinction from one another is therefore according to the degree of potency and act: the higher intelligence, being closer to the first, has more act and less potency, and so with the others.

And this is completed in the human soul, which holds the lowest degree among intellectual substances. Hence its possible intellect is related to intelligible forms as prime matter, which holds the lowest degree in sensible being, is related to sensible forms, as the Commentator says in On the Soul; and therefore the Philosopher compares it to a tablet on which nothing is written. Because it has more potency than the other intellectual substances, it consequently becomes so close to material things that a material thing is drawn to participate in its being: namely, from soul and body there results one being in one composite, although that being, insofar as it belongs to the soul, does not depend on the body. Therefore after this form, which is the soul, there are found other forms having more potency and being closer to matter, to such an extent that their being does not exist without matter. In these there is found an order and a gradation down to the primary forms of the elements, which are closest to matter; hence they have no operation except according to the requirements of the active and passive qualities and of the other qualities by which matter is disposed toward form.