De ente et essentia

It must be known, therefore, that, as the Philosopher says in Book V of the Metaphysics, being in itself is said in two ways: in one way, that which is divided into the ten genera; in another way, that which signifies the truth of a proposition. The difference between these, however, is that in the second way anything can be called being of which an affirmative proposition can be formed, even if it posits nothing in reality; in this way privations and negations are called beings. For we say that affirmation is opposed to negation, and that blindness is in the eye. But in the first way only that can be called being which posits something in reality; hence, in the first way, blindness and things of this kind are not beings.

The name “essence,” therefore, is not taken from being in the second sense just mentioned: for in this way some things are called beings that do not have an essence, as is clear in the case of privations; rather, essence is taken from being in the first sense. Hence the Commentator says in the same place that being said in the first way is that which signifies the essence of a thing. And since, as has been said, being in this sense is divided into the ten genera, essence must signify something common to all the natures through which diverse beings are placed in diverse genera and species, just as humanity is the essence of man, and likewise in other cases.

And since that through which a thing is constituted in its proper genus or species is what is signified by the definition stating what the thing is, it follows that philosophers change the name “essence” into the name “quiddity”; and this is also what the Philosopher frequently calls “that which it was to be,” that is, that through which something has the being of what it is. It is also called form, insofar as by form the determination of each thing is signified, as Avicenna says in Book II of his Metaphysics. It is also called nature by another name, taking nature according to the first of the four ways that Boethius assigns in the book On the Two Natures: namely, insofar as nature is called everything that can in some way be grasped by the intellect, for a thing is intelligible only through its definition and essence. Thus the Philosopher also says in Book V of the Metaphysics that every substance is a nature. Nevertheless, the name “nature,” taken in this way, seems to signify the essence of a thing insofar as it has an order to the thing’s proper operation, since no thing is without its proper operation; whereas the name “quiddity” is taken from the fact that it is signified through the definition. But “essence” is said insofar as through it and in it a being has being.

But since being is said absolutely and primarily of substances, and secondarily and, as it were, in a qualified sense of accidents, it follows that essence also is properly and truly in substances, but in accidents it is there in a certain way and in a qualified sense. Some substances, moreover, are simple and others composite, and essence is found in both; but in simple substances it is found in a truer and nobler way, just as they also have nobler being. For they are the cause of composite things—at least the first simple substance, which is God, is. But since the essences of those substances are more hidden from us, we must begin with the essences of composite substances, so that the instruction may proceed more suitably from what is easier.

In composite substances, therefore, form and matter are known, as in man, soul and body. But it cannot be said that either of these alone is called the essence. For it is clear that matter alone is not the essence of a thing, since a thing is both knowable through its essence and ordered in a species or genus; but matter is neither the principle of knowledge nor determined by it to a genus or species, but according to what a thing is in act. Nor can form alone be called the essence of a composite substance, although some try to assert this. For from what has been said it is clear that essence is what is signified by the definition of a thing; but the definition of natural substances contains not form alone but matter as well, otherwise natural and mathematical definitions would not differ.

Nor can it be said that matter is placed in the definition of a natural substance as something added to its essence, or as a being outside its essence, because this mode of definition belongs properly to accidents, which do not have a complete essence; hence in their definition they must receive a subject that lies outside their genus. It is therefore clear that essence comprehends both matter and form.

Nor can essence signify the relation between matter and form, or something superadded to them, because this would necessarily be an accident and extraneous to the thing, and a thing would not be known through it; whereas all these belong to essence. For through form, which is the act of matter, matter becomes a being in act and this particular thing. Hence what supervenes does not give matter being in act simply, but being in act of such-and-such a kind, just as accidents do: whiteness makes something actually white. Therefore, when such a form is acquired, a thing is not said to be generated simply, but in a qualified sense.

It remains, then, that in composite substances the name essence signifies what is composed of matter and form. This agrees with Boethius's statement in his commentary on the Categories, where he says that ousia signifies the composite; for among the Greeks ousia means the same as essence among us, as he himself says in On the Two Natures. Avicenna likewise says that the quiddity of composite substances is the very composition of form and matter. The Commentator also says, on Book VII of the Metaphysics: “The nature that species have in generable things is something intermediate, namely, composed of matter and form.” Reason agrees with this, since the being of a composite substance belongs neither to form alone nor to matter alone, but to the composite itself; and essence is that according to which a thing is said to be. Hence the essence by which a thing is denominated a being must be neither form alone nor matter alone, but both, although in its own way form alone is the cause of this being.

For in other things too that are constituted from several principles, we see that a thing is not denominated from only one of those principles, but from what embraces both. This is clear in flavors: sweetness is caused by the action of heat digesting moisture; and although heat is in this way the cause of sweetness, a body is not called sweet by its heat, but by its flavor, which embraces the hot and the moist.

But since matter is the principle of individuation, it might seem to follow that essence, which embraces matter and form together, is only particular and not universal. It would then follow that universals have no definition, if essence is what is signified by definition. We must therefore know that matter is not the principle of individuation in every way in which it is taken, but only designated matter; and I call designated matter that which is considered under determinate dimensions. This matter is not placed in the definition of man insofar as he is man, but it would be placed in the definition of Socrates, if Socrates had a definition.

In the definition of man, however, undesignated matter is placed: the definition does not contain this bone and this flesh, but bone and flesh absolutely, which are the undesignated matter of man.

Thus it is clear that the essence of man and the essence of Socrates differ only according to the designated and the undesignated. Hence the Commentator says on Book VII of the Metaphysics: “Socrates is nothing other than animality and rationality, which are his quiddity.”

The essence of genus and species likewise differ according to the designated and the undesignated, although the mode of designation is different in the two cases. The designation of an individual with respect to a species is through matter determined by dimensions; the designation of a species with respect to a genus is through the constitutive difference taken from the form of the thing. But this determination or designation of the species with respect to the genus is not through something existing in the essence of the species that is in no way in the essence of the genus. Rather, whatever is in the species is also in the genus, though not determined. For if animal were not the whole of what man is but a part of him, it would not be predicated of him, since no integral part is predicated of its whole.

How this occurs can be seen by considering how body differs insofar as it is posited as a part of animal and insofar as it is posited as a genus; for it cannot be a genus in the same way as it is an integral part. The name body, therefore, can be taken in several ways. Body, insofar as it is in the genus of substance, is said from having a nature such that three dimensions can be designated in it; the three designated dimensions themselves are the body that is in the genus of quantity.

In things it happens that what has one perfection reaches a further perfection as well, as is clear in man, who has a sensitive nature and, beyond it, an intellectual nature. Likewise, upon the perfection of having such a form that three dimensions can be designated in it, another perfection may be added, such as life or something of the kind. The name body can therefore signify a thing having a form from which the designability of three dimensions follows, with a restriction: namely, that no further perfection follows from that form, and if anything else is added, it lies outside the signification of body so understood. In this way body is the integral and material part of animal, because soul lies outside what is signified by the name body and supervenes upon body, so that animal is constituted from the two, soul and body, as from its parts.

The name body can also be taken to signify a thing having a form from which three dimensions can be designated in it, whatever that form may be, whether a further perfection can proceed from it or not. In this way body is the genus of animal, because in animal there is nothing to be taken that is not implicitly contained in body. Soul is not another form than that through which three dimensions could be designated in that thing. Thus, when body was said to be what has such a form that three dimensions can be designated in it, any form whatever was understood, whether soul, stoniness, or anything else. In this way the form of animal is implicitly contained in the form of body, insofar as body is its genus.

Animal also bears this relation to man. If animal signified only a thing having a perfection such that it could sense and move through a principle existing in it, with the restriction of another perfection, then every further perfection would be related to animal as a co-part, and not as implicitly contained in the notion of animal; thus animal would not be a genus. But it is a genus insofar as it signifies a thing from whose form sensation and movement can proceed, whatever that form may be, whether it is merely a sensitive soul or a sensitive and rational soul together.

Thus genus signifies indeterminately the whole that is in the species; it does not signify matter alone. Difference likewise signifies the whole, not form alone; and definition, and species, also signify the whole. They do so in different ways. Genus signifies the whole as a denomination determining what is material in the thing without determining its proper form; hence genus is taken from matter, although it is not matter. Body is an example, since it is said from having such a perfection that three dimensions can be designated in it, and this perfection stands materially in relation to a further perfection.

Difference, conversely, is a denomination taken from a determinate form, except that determinate matter is not included in its first understanding. Thus “animate” means that which has a soul, without determining what it is, whether body or something else. Avicenna therefore says that genus is not understood in difference as a part of its essence, but only as a being outside its essence, just as a subject is included in the understanding of passions. Hence genus, strictly speaking, is not predicated of difference, as the Philosopher says in Book III of the Metaphysics and Book IV of the Topics, unless perhaps as a subject is predicated of a passion. Definition or species, however, comprehends both: the determinate matter designated by the name genus and the determinate form designated by the name difference.

From this the reason is clear why genus, species, and difference correspond proportionally to matter, form, and composite in nature, although they are not identical with them. Genus is not matter, but is taken from matter while signifying the whole; nor is difference form, but is taken from form while signifying the whole. Thus we say that man is rational animal, not that he is made from animal and rational as we say that he is made from soul and body. From soul and body man is said to be made as a third thing constituted from two things, which he is neither of: man is neither soul nor body. But if man is in some way said to be made from animal and rational, this is not as a third thing from two things, but as a third understanding from two understandings. The understanding of animal is without determination of a specific form, expressing the nature of a thing according to what is material in relation to the ultimate perfection; the understanding of rational consists in determination of a specific form. From these two understandings is constituted the understanding of the species or definition. Therefore, just as a thing constituted from certain things does not receive their predication, so neither does an understanding receive the predication of the understandings from which it is constituted: we do not say that a definition is genus or difference.

Although genus signifies the whole essence of a species, it does not follow that the essence of different species having the same genus is one essence, because the unity of genus proceeds from its indetermination or indifference. It is not that what is signified by genus is one numerically identical nature in different species, with another thing, the difference, supervening to determine it, as form determines matter, which is one in number. Rather, genus signifies a form—not this or that determinate form—which the difference expresses; and the form expressed by the difference is not other than the form signified indeterminately by the genus. Hence the Commentator says in Book XI of the Metaphysics that prime matter is called one by removal of all forms, whereas genus is called one by the community of the form signified. It is therefore clear that, when the indetermination that caused the unity of genus is removed by addition of the difference, species remain essentially diverse.

And because, as has been said, the nature of the species is indeterminate with respect to the individual just as the nature of the genus is with respect to the species, it follows that, just as genus, when predicated of the species, implicitly signified in its meaning, though indistinctly, the whole that is determinate in the species, so what is species, when predicated of an individual, must signify the whole that is essential in the individual, though indistinctly. In this way the essence of the species is signified by the name man, and man is predicated of Socrates.

But if the nature of the species is signified with restriction from designated matter, which is the principle of individuation, it has the character of a part. In this way it is signified by the name humanity, for humanity signifies that by which man is man. Designated matter is not that by which man is man, and therefore is in no way contained among the things from which man has his being man. Since humanity in its understanding includes only those things from which man has his being man, designated matter is excluded or cut off from its signification. And because a part is not predicated of the whole, humanity is predicated neither of man nor of Socrates. Hence Avicenna says that the quiddity of a composite is not the composite itself whose quiddity it is, although the quiddity itself is composite; thus humanity, although composite, is not man. Rather, it must be received in something that is designated matter.

But since, as has been said, the designation of a species with respect to a genus is through form, while the designation of an individual with respect to a species is through matter, it is therefore necessary that a name signifying that from which the nature of the genus is taken, with the restriction of the determinate form perfecting the species, signify the material part of the whole, just as body is the material part of man; whereas a name signifying that from which the nature of the species is taken, with the restriction of designated matter, signifies the formal part. Therefore humanity is signified as a certain form and is called the form of the whole—not as though superadded to the essential parts, namely form and matter, as the form of a house is superadded to its integral parts, but rather as the form that is the whole, comprehending form and matter, though with the restriction of the principles through which matter is apt to be designated.

It is therefore clear that the name man and the name humanity signify the essence of man, but in different ways. The name man signifies it as a whole, since it does not cut off the designation of matter but implicitly and indistinctly contains it, just as genus was said to contain difference; hence the name man is predicated of individuals. The name humanity signifies it as a part, because its signification contains only what belongs to man insofar as he is man and cuts off every designation; hence it is not predicated of individual men. For this reason the name essence is sometimes found predicated of a thing: we say that Socrates is a certain essence; and sometimes it is denied, as when we say that the essence of Socrates is not Socrates.

Having seen, then, what is signified by the name essence in composite substances, we must consider how it is related to the notion of genus, species, and difference. Since, moreover, that to which the notion of genus, species, or difference belongs is predicated of the designated singular, it is impossible that the notion of universal—namely, of genus or species—belong to the essence insofar as it is signified in the manner of a part, as by the name humanity or animality. Hence Avicenna says that rationality is not a difference but the principle of a difference; and for the same reason humanity is not a species, nor animality a genus.

Likewise, it cannot be said that the notion of genus or species belongs to the essence insofar as it is some existing thing outside singulars, as the Platonists posited. For in that case genus and species would not be predicated of this individual: one could not say that Socrates is that which is separated from him; nor would that separated thing contribute to knowledge of this singular. It therefore remains that the notion of genus or species belongs to the essence insofar as it is signified in the manner of a whole, as by the name man or animal, insofar as it implicitly and indistinctly contains the whole of what is in the individual.

Nature or essence, so understood, can be considered in two ways. In one way, according to its proper notion; this is its absolute consideration. In this way nothing is true of it except what belongs to it as such; hence whatever else is attributed to it is a false attribution. For example, rational and animal, and other things that enter into the definition of man, belong to man insofar as he is man; but white or black, or anything of this sort that does not belong to the notion of humanity, does not belong to man insofar as he is man. Thus, if it is asked whether this nature, so considered, can be called one or many, neither may be granted, because both are outside the understanding of humanity, and either can befall it. For if plurality belonged to its understanding, it could never be one, although it is one insofar as it is in Socrates. Likewise, if unity belonged to its notion, then it would be one and the same in Socrates and Plato, and could not be multiplied in many.

In another way, it is considered according to the being that it has in this or that; and in this way something is predicated of it accidentally, by reason of that in which it is, as when it is said that man is white because Socrates is white, although this does not belong to man insofar as he is man.

This nature has a twofold being: one in singulars and another in the soul; and according to each, accidents follow upon the nature in question. In singulars, too, it has multiple being according to the diversity of singulars. Yet none of these kinds of being is owed to the nature itself according to its first consideration, namely, the absolute one. For it is false to say that the essence of man, insofar as it is such, has being in this singular; for if being in this singular belonged to man insofar as he is man, he would never be outside this singular. Likewise, if not being in this singular belonged to man insofar as he is man, he would never be in it. But it is true to say that man, not insofar as he is man, has it that he is in this singular or that one, or in the soul. Therefore it is clear that the nature of man, absolutely considered, abstracts from every being, yet without making a precision of any of them. And this nature, so considered, is what is predicated of all individuals.

Nevertheless, it cannot be said that the notion of universal belongs to nature so accepted, because unity and commonality belong to the notion of universal; neither of these, however, belongs to human nature according to its absolute consideration. For if commonality belonged to the understanding of man, then wherever humanity were found, commonality would be found; and this is false, because no commonality is found in Socrates, but everything that is in him is individuated. Likewise, it cannot be said that the notion of genus or species befalls human nature according to the being it has in individuals, because in individuals human nature is not found according to unity, so as to be one thing belonging to all, which the notion of universal requires. It therefore remains that the notion of species befalls human nature according to the being it has in the intellect. Indeed, human nature itself has in the intellect a being abstracted from all individuating features; and therefore it has a uniform relation to all the individuals outside the soul, insofar as it is equally the likeness of all and leads to knowledge of all insofar as they are men. From the fact that it has such a relation to all individuals, the intellect devises the notion of species and attributes it to the nature. Hence the Commentator says at the beginning of On the Soul that “the intellect is what produces universality in things”; Avicenna says this too in his Metaphysics.

Although this understood nature has the notion of universal insofar as it is compared with things outside the soul, because it is one likeness of all, nevertheless, insofar as it has being in this intellect or that one, it is a particular understood species. Hence the Commentator’s error is clear in Book III of On the Soul, where he wished to conclude the unity of the intellect in all men from the universality of the understood form. For that form is not universal insofar as it has this being in the intellect, but insofar as it is related to things as their likeness; just as, if there were one corporeal statue representing many men, it is clear that the image or species of the statue would have singular and proper being insofar as it were in this matter, but would have the notion of commonality insofar as it were a common representation of several.

And because it belongs to human nature according to its absolute consideration that it be predicated of Socrates, while the notion of species does not belong to it according to its absolute consideration but is among the accidents that follow upon it according to the being it has in the intellect, the name species is not predicated of Socrates, so that one would say “Socrates is a species.” This would necessarily follow if the notion of species belonged to man according to the being he has in Socrates, or according to his absolute consideration, namely, insofar as he is man; for whatever belongs to man insofar as he is man is predicated of Socrates.

And yet, since being predicated belongs to genus per se, it is posited in its definition. For predication is something completed through the action of the intellect composing and dividing, having in the thing itself a foundation, namely, the unity of those things one of which is said of the other. Hence the notion of predicability can be included in the notion of this intention, which is genus, and which likewise is completed through an act of the intellect. Nevertheless, that to which the intellect attributes the intention of predicability, composing it with another, is not the intention of genus itself, but rather that to which the intellect attributes the intention of genus, such as what is signified by the name animal.

Thus it is clear how essence or nature is related to the notion of species: the notion of species is not among those things that belong to it according to its absolute consideration, nor is it among the accidents that follow upon it according to the being it has outside the soul, such as whiteness and blackness; rather, it is among the accidents that follow upon it according to the being it has in the intellect. In this way, the notion of genus or difference also belongs to it.

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.

Having seen these things, it is clear how essence is found in different things. For there are three modes of possessing essence in substances. One is like God, whose essence is his very being; and therefore some philosophers say that God does not have a quiddity or essence, because his essence is nothing other than his being. From this it follows that he is not in a genus, because everything that is in a genus must have a quiddity distinct from its being, since the quiddity or nature of the genus or species is not distinguished according to the nature's intelligible account in those of which it is the genus or species, whereas being is diverse in diverse things.

Nor, if we say that God is being alone, need we fall into the error of those who said that God is that universal being by which each thing formally is. For this being which God is has the condition that no addition can be made to it; hence, through its very purity, it is being distinct from every other being. For this reason, in the commentary on proposition nine of the Book of Causes it is said that the individuation of the first cause, which is being alone, is through its pure goodness. Now, just as being, according to its intelligible account, does not include any addition, so neither does its intelligible account include the exclusion of an addition. For if being were something common, something would have to be added to that being by which it would be determined to this or that thing, just as form is determined by matter. Thus God has nothing added to his being itself: for this reason he is pure and simple being.

Likewise, although he is being alone, it does not follow that the other perfections and nobilities are lacking in him. Indeed, he has all the perfections found in all genera, for which reason he is called simply perfect, as the Philosopher and the Commentator say in Book V of the Metaphysics; but he has them in a more excellent mode than all things, because in him they are one, whereas in other things they have diversity. This is because all those perfections belong to him according to his simple being. Thus, if someone could produce the operations of all qualities through one quality, he would possess all qualities in that one quality; so God possesses all perfections in his very being.

In a second way essence is found in created intellectual substances, in which their being is other than their essence, although their essence is without matter. Hence their being is not absolute but received, and therefore limited and finite according to the capacity of the receiving nature; but their nature or quiddity is absolute, not received in some matter. Therefore it is said in the Book of Causes that intelligences are infinite below and finite above: they are finite with respect to their being, which they receive from a higher being, but they are not bounded below, because their forms are not limited to the capacity of some matter receiving them. Consequently, in such substances a multitude of individuals in one species is not found, except in the human soul because of the body to which it is united. And although its individuation depends accidentally on the body with respect to its beginning, individuated being is not acquired by it except in the body of which it is the act; nevertheless, when the body is taken away, individuation need not perish, because, since it has absolute being, from which individuated being was acquired for it by becoming the form of this body, that being always remains individuated. Hence Avicenna says that the individuation and multiplication of souls depends on the body with respect to its beginning, but not with respect to its end.

And because in these substances quiddity is not the same as being, they can therefore be ordered in a category; and for this reason genus, species, and difference are found in them, although their proper differences are hidden from us. For in sensible things the essential differences themselves are also unknown; hence they are signified through accidental differences arising from the essential ones, just as a cause is signified through its effect: thus biped is posited as the difference of human being. But the proper accidents of immaterial substances are unknown to us, and therefore their differences can be signified by us neither through themselves nor through accidental differences.

Nevertheless, one must know that genus and difference are not taken in the same way in those substances and in sensible substances. For in sensible substances genus is taken from what is material in the thing, while difference is taken from what is formal in it. Hence Avicenna says at the beginning of his Book of the Soul that form in things composed of matter and form “is its simple difference which is constituted from it”; not, however, in the sense that the form itself is the difference, but because it is the principle of the difference, as he says in the same way in his Metaphysics. Such a difference is called a simple difference because it is taken from what is a part of the thing, namely, the form. But since the quiddities of immaterial substances are simple quiddities, in them difference cannot be taken from what is a part of the quiddity, but from the whole quiddity. Therefore at the beginning of the Book of the Soul Avicenna says that “only those species whose essences are composed of matter and form have a simple difference.”

Likewise, in them genus is taken from the whole essence, but in a different way. One separate substance agrees with another in immateriality, but they differ from one another in degree of perfection according to their withdrawal from potentiality and approach to pure act. Therefore, from what follows upon them insofar as they are immaterial, genus is taken in them, such as intellectuality or something of this sort; but from what follows upon them according to their degree of perfection, difference is taken in them, although it is unknown to us. Nor need these differences be accidental, because they are according to greater and lesser perfection, which do not diversify the species. For a degree of perfection in receiving the same form does not diversify the species, as what is whiter and less white do not differ in species when participating in whiteness according to the same account; but a diverse degree of perfection in the forms or natures themselves that are participated does diversify the species, as nature proceeds by degrees from plants to animals through certain things intermediate between animals and plants, according to the Philosopher in Book VII of On Animals. Nor again is it necessary that the division of intellectual substances always be through two true differences, because it is impossible for this to occur in all things, as the Philosopher says in Book XI of On Animals.

In a third way essence is found in substances composed of matter and form. In them being is received and finite because they have being from another, and again their nature or quiddity is received in designated matter. Therefore they are finite both above and below; and in them, because of the division of designated matter, the multiplication of individuals in one species is now possible. And how essence is related to logical intentions in these things was said above.

Now it remains to see how essence is found in accidents; for how it is found in all substances has been stated. And because, as was said, essence is that which is signified by a definition, they must have essence in the manner in which they have a definition. But they have an incomplete definition, because they cannot be defined unless the subject is posited in their definition; and this is because they do not have absolute being through themselves apart from a subject, but just as substantial being remains from form and matter when they are composed, so accidental being remains from an accident and a subject when the accident comes to the subject. Hence neither substantial form nor matter has a complete essence, because in the definition of substantial form too that of which it is the form must be posited, and thus its definition is by the addition of something outside its genus, just as is the definition of accidental form; hence in the definition of the soul the body is posited by the natural philosopher, who considers the soul only insofar as it is the form of a physical body.

Yet there is this difference between substantial and accidental forms: just as substantial form does not have absolute being through itself without that which it comes to, so neither does that which it comes to, namely matter; and therefore from the conjunction of both there remains that being in which the thing subsists through itself, and from them there is made one thing through itself. For this reason a certain essence results from their conjunction. Hence, although form, considered in itself, does not have the complete character of essence, it is nevertheless a part of a complete essence.

But that which an accident comes to is an entity complete in itself, subsisting in its own being; and this being naturally precedes the accident that supervenes. Therefore an accident supervening, from its conjunction with that which it comes to, does not cause the being in which the thing subsists, through which the thing is an entity through itself; rather, it causes a certain secondary being, without which the subsisting thing can nevertheless be understood to exist, just as the first can be understood without the second. Hence from an accident and a subject there is not made one thing through itself, but one thing accidentally. Therefore from their conjunction no essence results, as it does from the conjunction of form with matter; for this reason an accident neither has the character of a complete essence nor is a part of a complete essence, but just as it is an entity in a qualified sense, so it also has essence in a qualified sense.

But because that which is said to be so chiefly and most truly in any genus is the cause of those that come after it in that genus, just as fire, which is at the extreme of heat, is the cause of heat in hot things, as is said in Book II of the Metaphysics, substance, which is first in the genus of entities and has essence most truly and chiefly, must be the cause of accidents, which participate in the character of entity secondarily and, as it were, in a qualified sense. This nevertheless occurs in different ways. Since the parts of substance are matter and form, some accidents consequently belong chiefly to form and some to matter. Now there is a form whose being does not depend on matter, namely the intellectual soul; but matter has no being except through form. Hence among the accidents that follow form there is something that has no communication with matter, such as understanding, which is not through a bodily organ, as the Philosopher proves in Book III of On the Soul; but some of the consequences of form have communication with matter, such as sensation. No accident, however, follows matter without communication with form.

Among these accidents that follow matter, nevertheless, a certain difference is found. For some accidents follow matter according to the order it has to a specific form, such as male and female in animals, whose difference is reduced to matter, as is said in Book X of the Metaphysics; hence, when the animal form mentioned is removed, these accidents do not remain except equivocally. Others follow matter according to the order it has to a general form; and therefore, when the specific form is removed, they still remain in it, such as the blackness of the skin in an Ethiopian, which is from the mixture of the elements and not from the character of the soul, and therefore remains in him after death.

And because each thing is individuated from matter and placed in a genus or species through its form, the accidents that follow matter are therefore accidents of the individual, according to which individuals even of the same species differ from one another; but the accidents that follow form are properly properties of either a genus or a species. Hence they are found in all those participating in the nature of the genus or species, as the risible follows the form in man, because laughter occurs from some apprehension of the human soul. It should also be known that accidents are sometimes caused by essential principles according to a perfect act, such as heat in fire, which is always hot; but sometimes according to aptitude alone, while completion comes from an external agent, such as transparency in air, which is completed through an external luminous body. In such cases aptitude is an inseparable accident, but the completion that comes from some principle outside the essence of the thing, or that does not enter into the constitution of the thing, is separable, such as being moved and the like.

It should also be known that in accidents genus, difference, and species are taken in another way than in substances. Since in substances substantial form and matter make one thing through itself, a certain nature resulting from their conjunction, which is properly placed in the predicament of substance, concrete names signifying the composite are therefore properly said to be in a genus, as species or genera, such as man or animal. But form or matter is not in a predicament in this way except by reduction, just as principles are said to be in a genus. From an accident and a subject, however, one thing through itself is not made; hence no nature results from their conjunction to which the intention of genus or species could be attributed. Therefore concrete accidental names are not placed in a predicament as species or genera, such as white or musical, except by reduction; they are placed there only insofar as they are signified abstractly, such as whiteness and music.

And because accidents are not composed of matter and form, genus cannot be taken in them from matter and difference from form, as in composite substances; rather, the first genus must be taken from the very mode of being, according to which entity is said in different ways, according to priority and posteriority, of the ten genera of the predicaments. Thus quantity is so called insofar as it is the measure of substance, and quality insofar as it is a disposition of substance, and so with the others, according to the Philosopher in Book IX of the Metaphysics.

Differences in them, however, are taken from the diversity of the principles from which they are caused. And because proper properties are caused from the proper principles of the subject, the subject is therefore placed in their definition in place of the difference when they are defined abstractly, insofar as they are properly in a genus, as when it is said that snubness is the curvature of the nose. Conversely, it would be otherwise if their definition were taken according to the way they are said concretely: for then the subject would be placed in their definition as genus, since they would be defined in the manner of composite substances.

And if one accident is the principle of another accident, such as action, passion, and quantity are the principles of relation, the Philosopher therefore divides relation according to these in Book V of the Metaphysics. But because the proper principles of accidents are not always manifest, we sometimes take the differences of accidents from their effects, as “congregative” and “disgregative” are called the differences of color, which are caused by an abundance or scarcity of light, from which the diverse species of color are caused.

Thus it is clear how essence is found in substances and accidents, and how it is found in composite and simple substances, and how universal intentions are logically found in all these; except for the first, which is at the limit of simplicity, to which the character of genus or species, and consequently definition, does not belong because of its simplicity. Here ends and is completed this treatise. Amen.