In De ente et essentia D. Thomae Aquinatis commentaria

On the essence of simple substances compared with the essence of composite substances. Simple substances, which are forms alone, are composed of essence and being, and proceed from God as from an efficient cause.

Now it remains to see in what manner essence is in separated substances, namely in the soul, the intelligences, and the first cause. Although all philosophers concede the simplicity of the first cause, nevertheless some strive to posit a composition of matter and form in the intelligences and souls; Avicebron, the author of the book The Fountain of Life, is said to have held this position. But this is found to be contrary to the statements of the philosophers, because they call those substances separated from matter and prove them to be without all matter; the strongest demonstration of this is 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 intelligent substance, insofar as they are received in it and insofar as they are acted upon through it. Hence there must be in every intelligent substance complete immunity from matter, so that it neither has matter as a part of itself nor is like a form impressed in matter, as is the case with material forms.

Here the second treatise of this work begins, intending in two chapters to hand down knowledge of the essences of simple substances, just as knowledge of the essences of composite substances was handed down. In the present chapter he does six things. First he declares that essence in simple things does not signify something composed of matter and form, but form alone. Second he compares those essences with the essences of composite substances. Third he shows that such substances are composed of being and essence. Fourth he declares that the intelligences have being effectively from God. Fifth he shows that they are composed of act and potency. Sixth he treats of their multitude. Having first proposed the philosophers’ unanimous opinion concerning the complete simplicity of the first cause, and having brought forward certain dissenters concerning the immateriality of the intelligences, against them he posits this conclusion: every intellectual substance is immaterial, that is, not composed of matter and form, and independent of matter. He proves it thus: everything undergoing, acting, receiving, or having an actually intelligible thing in itself is immaterial; every intellectual substance undergoes, acts, receives, or has an actually intelligible thing in itself; therefore every intellectual substance is immaterial. The major, as to its three parts, is proved from the same middle term, namely from the fact that what is actually intelligible must be immaterial, On the Soul III, texts XI and XV; and an agent producing an immaterial thing must be immaterial, because an agent cannot be less noble than its effect, as is said in On the Soul III, texts XVIII and XL; nor can an immaterial thing be received except by an immaterial thing, as is clear in On the Soul III, commentary V: each thing is received according to the mode of the receiver. By the same reasoning it is evident that only an immaterial thing can have in itself an immaterial cognoscible. The minor is conceded by everyone. For an intellectual substance would be useless unless it understood something, since everything exists for the sake of its operation, as is said in On the Heavens II, text XVII.

Nor can anyone say that matter of every kind does not impede intelligibility, but only corporeal matter. For if this were so solely by reason of corporeal matter, since matter is not called corporeal except insofar as it stands under a corporeal form, then matter would have from corporeal form this property, namely to impede intelligibility. This cannot be, because corporeal form itself is actually intelligible, just as other forms are, insofar as they are abstracted from matter. Hence in the intellectual soul and in an intelligence there is in no way a composition of matter and form, if matter is taken in them in the way it is taken in corporeal 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 an intelligence has form and being, and there “form” is taken for the simple quiddity or essence itself.

Because someone might believe that the argument made receives a response, he therefore intends here to exclude a response which might be imagined sufficient. Someone could distinguish between corporeal matter and matter simply speaking, and say that the major is true of corporeal matter but not of matter simply speaking, and consequently concede that every intellectual substance is immune from corporeal matter but not from matter, because it is not matter, but corporeal matter, that impedes intelligibility in act.

Against this evasion an argument leading to the impossible is urged as follows: Corporeal matter per se impedes intelligibility; therefore corporeal form is that from which matter has its impediment to intelligibility. This is impossible; therefore, by destruction of the consequent, etc. The consequence is evident from the terms. Since corporeal matter signifies two things, namely “matter” and “corporeal,” and according to the adversary intelligibility in act is not impeded by “matter,” it remains that the impediment comes from “corporeal.” But “corporeal” adds nothing to matter except corporeal form; therefore it arises from corporeal or bodily form that matter impedes intelligibility in act. The falsity of the consequent is proved thus: every form not conceived together with matter is actually intelligible, as is clear from On the Soul III, text 11. Corporeal form is, in itself, a form not conceived together with matter, for it is taken as distinct from matter; therefore corporeal form in itself is actually intelligible. Further: nothing that is in itself actually intelligible provides, of itself, an impediment to intelligibility; corporeal form is such; therefore corporeal form is not that from which matter derives its impediment to intelligibility, which was to be proved. Thus neither the intellective soul nor any intelligence is composed of matter and form, if we take “composition from matter and form” univocally, namely as matter and form naming the essential parts of a thing, as was said above concerning certain composed substances. Rather, there is in them another kind of composition, namely from form and being, which will be discussed below. Thus the first part of the intended conclusion is obtained: essence in intellectual substances does not signify something composed of matter and form. It remains to explain how it signifies form alone; therefore he adds:

And how this is so is easy to see. Whatever are so related that one is the cause of the other’s being, that which has the character of cause can have being without the other, but not conversely. Matter and form are found to be related in this way: form gives being to matter, and therefore it is impossible for any matter to exist without 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 nearest to the first principle are forms subsisting in themselves without matter. Form does not need matter according to its whole genus, as was said; and such forms are intelligences. Therefore the essences or quiddities of these substances need be nothing other than form itself.

Intending in these words to explain how essence in simple substances signifies form alone, he proves it by this reasoning: whatever are so related that one is the cause of the other’s being, and not conversely, that which has the character of cause can exist without the other; but form and matter are so related that form causes the being of matter, and not conversely; therefore form can exist without matter, and matter not without form. Further: the essence of intelligences is not composed of matter and form, and it cannot be matter alone; therefore it is form alone.

Note that the major proposition can be understood in two ways. In one way, that what is the cause of another, etc., can be numerically the same while existing without the other; this is not assumed by us, because it is false and beside the point. It is false because a subject causes the being of its proper passion, and not conversely, yet the subject cannot exist without its proper passion. It is beside the point because we do not wish to conclude that the form which is in matter exists without matter, but that some form does not require matter. In another way, the major is understood to mean that what has the character of cause according to its order can exist without the other—that is, something belonging to its order can be found without the other—and in this way it is true and relevant. It is true because, since a cause is independent of its effect, it follows that something belonging to its order can have being outside the effect. It is relevant because we intend to conclude that form according to its genus does not depend on matter, so that some form can be found separate. Hence in the minor it is carefully not “material form,” or form having being in matter, that is assumed, but “form” without qualification, to suggest that we are speaking of form insofar as it is form, not insofar as it is this or that form.

That minor is clear from Metaphysics IX, texts 13 and 15, where it is stated that act is simply prior to potency and independent of it. Since form is essentially act, while matter is essentially potency, if act according to its entire scope does not depend on potency, it follows that form according to its whole order does not depend on matter. Since matter is essentially potency, it must depend on form, without which actuality is not found. Thus the minor is clear: matter depends for its being on form absolutely, insofar as it is form, just as potency depends on act, and not conversely. That it belongs to some act not to be found except received in a potency arises from its imperfection, not from its being act; likewise, that some forms exist only in matter arises from their imperfection, measured by their distance from the first principle, glorious God, and their proximity to prime matter. Hence such forms not only cause matter to be, but are themselves in a way caused by matter. For causes are causes of one another, as is said in Physics II, text 30. Therefore the essence of intellectual substances is immaterial and form alone.