Chapter 4 — How essences exist in separated substances

We should now see how essences exist in separated substances, that is, in the soul, in the intelligences, and in the first cause. Now, although everyone concedes the simplicity of the first cause, some people have tried to introduce into the intelligences and the soul a composition of form and matter, a position that seems to have begun with Avicebron, the author of the book called Fons vitae. But this view is repugnant to the common teaching of the philosophers, for they call these things substances separated from matter, and they prove them to be wholly without matter. The most cogent demonstration of this proceeds from the excellence of understanding found in these substances. For we see that forms are not actually intelligible except as they are separated from matter and its conditions, and forms are not made actually intelligible except by virtue of an intelligent substance in which they are received and through which they are brought about. Hence, in any intelligent substance there is a complete absence of matter in such a way that the substance has neither a material part itself, nor even is the substance like a form impressed in matter, as is the case with material forms.

Nor can someone say that only corporeal matter, and not some other kind of matter, impedes intelligibility. For, if it were only corporeal mater that impedes intelligibility, then, since matter is called corporeal only insofar as it exists under a corporeal form, it would follow that matter impedes intelligibility by the corporeal form; and this is impossible, for the corporeal form is actually intelligible just like any other form, insofar as it is abstracted from matter. Hence, in no way is there a composition of matter and form in either the soul or the intelligences, such that an essence is received in these as in corporeal substances. Nevertheless, in separate substances there is a composition of form and existence, and so in the Liber de causis 9, it is said that the intelligences have form and existence: and in this place form is taken in the sense of a simple quiddity or nature.

It is easy to see how this is the case. Whenever two things are related to each other such that one is the cause of the other, the one that is the cause can have existence without the other, but not conversely. Now, we find that matter and form are related in such a way that form gives existence to matter, and therefore it is impossible that matter exist without a form; but it is not impossible that a form exist without matter, for a form, insofar as it is a form, is not dependent on matter. If we should find some forms that cannot exist except in matter, this happens because such forms are distant from the first principle, which is primary and pure act. Hence, those forms that are nearest the first principle are subsisting forms essentially without matter, for not the whole genus of forms requires matter, as said above, and the intelligences are forms of this type. Thus, the essences or quiddities of these substances are not other than the forms themselves.

Therefore, the essence of a composite substance and that of a simple substance differ in that the essence of a composite substance is not form alone but embraces both form and matter, while the essence of a simple substance is form alone. And from this two other differences arise. One is that the essence of a composite substance can be signified as a whole or as a part, which happens because of the designation of the matter, as said above. Hence, the essence of a composite thing is not in every way predicated of the composite thing itself, for we cannot say that a man is his own quiddity. But the essence of a simple thing, which is its form, cannot be signified except as a whole, as in this case there is nothing beyond the form to receive the quiddity. And so, however we take the essence of a simple thing, the essence is predicated of it. Hence, Avicenna says (Metaphysics 5.5) that the quiddity of a simple thing is the simple thing itself, because there is no other thing to receive the form. The second difference is that the essences of composite things, because they are received in designate matter, are multiplied according to the division of matter, and so it happens that some such things are the same in species but different in number. But since the essence of a simple thing is not received in matter, there can be no such multiplication in this case, and so among such substances we do not find many individuals of the same species, but rather there are as many species as there are individuals, as Avicenna expressly says in Metaphysics 5.2.

Although substances of this kind are form alone and are without matter, they are nevertheless not in every way simple, and they are not pure act. Rather, they have an admixture of potency, and this can be seen as follows. Whatever is not in the concept of the essence or the quiddity comes from outside the essence and makes a composition with the essence, because no essence can be understood without the things that are its parts. But every essence or quiddity can be understood without understanding anything about its existence: I can understand what a man is or what a phoenix is, and nevertheless not know whether either has existence in reality. Therefore, it is clear that existence is something other than the essence or quiddity, unless perhaps there is something whose quiddity is its very own existence, and, if so, this thing must be one and primary. For there can be no plurification of something except by the addition of some difference, as the nature of a genus is multiplied in its species; or as the nature of the species is multiplied in diverse individuals since the form is received in diverse matters; or again as when one thing is absolute and another is received in something else, as if there were a certain separate heat that was other than unseparated heat by reason of its separation. But if we posit a thing that is existence only, such that it is subsisting existence itself, this existence will not receive the addition of a difference. For, if there were added a difference, it would be not only existence, but existence and also some form beyond this. Much less would such a thing receive the addition of matter, for then the thing would be not subsisting existence but material. Hence, it remains that a thing that is its own existence cannot be other than one, and so in every other thing, the thing’s existence is one thing, and its essence or quiddity or nature or form is another. In the intelligences, therefore, there is existence beyond the form, and so we say that an intelligence is form and existence.

Everything that pertains to a thing, however, either is caused by the principles of its own nature, as risibility in man, or else comes from some extrinsic principle, as light in the air from the influence of the sun. Now, it cannot be that existence itself is caused by the very form or quiddity of the thing (I mean as by an efficient cause), because then the thing would be its own efficient cause, and the thing would produce itself in existence, which is impossible. Therefore, everything the existence of which is other than its own nature has existence from another. And since everything that is through another is reduced to that which is through itself as to a first cause, there is something that is the cause of existence in all things in that this thing is existence only. Otherwise, we would have to go to infinity in causes, for everything that is not existence alone has a cause of its existence, as was said above. It is clear, therefore, that the intelligences are form and existence and have existence from the first being, which is existence alone, and this is the first cause, which is God.

Everything that receives something from another is in potency with respect to what it receives, and that which is received in the thing is its act. Therefore, a quiddity or form that is an intelligence is in potency with respect to the existence that it receives from God, and this received existence is received as its act. And thus there are found in the intelligences both potency and act, but not matter and form, unless in some equivocal sense. Hence it is also clear that ‘to suffer,’ ‘to receive,’ ‘to be a subject’ and everything of this type that seem to pertain to things by reason of their matter are said of intellectual substances and corporeal substances equivocally, as the Commentator says in de Anima 3, com. 14. Furthermore, since, as was said above, the quiddity of an intelligence is the intelligence itself, its quiddity or essence is itself the very thing that exists, and its existence received from God is that by which it subsists in reality; and because of this some people say that substances of this kind are composed of what is and that by which it is, or of what is and existence, as Boethius says in de Hebdomadibus. (PL 64, 1311 B–C.)

Moreover, since we posit in the intelligences potency and act, it will not be difficult to find a multitude of intelligences, which would be impossible if there were in them no potency. Hence, the Commentator says in de Anima 3, com. 5 that if the nature of the possible intellect were unknown, we would not be able to find a multitude of separate substances. There is thus a distinction among separate substances according to their grade of potency and act such that the superior intelligences, which are nearer the first cause, have more act and less potency, and so on.

This scale comes to an end with the human soul, which holds the lowest place among intellectual substances. The soul’s possible intellect is related to intelligible forms just as prime matter (which holds the lowest place in sensible existence) is related to sensible forms, as the Commentator says in de Anima 3, com. 5. The Philosopher thus compares the soul to a tablet on which nothing has been written, in de Anima 3.4. (Aristotle, de Anima, 430a1.) Since the soul has the most potency among the intellectual substances, it is so close to material things that a material thing is brought to participate in its existence: that is, from the soul and the body there results one existence in one composite thing, although this existence, as the existence of the soul, is not dependent on the body. Beyond this form that is the soul, there are other forms having more potency and being closer to matter, and so much so that they have no existence without matter. Among these forms there is an order and gradation down to the primary forms of the elements, which are closest to matter; and so these have no operation except as required by the active and passive qualities and other such qualities by which matter is disposed by form.