This little treatise, whose composition is thought to be contemporary with the preceding, is an indisputable proof of the genius of its author. Here some of the most vexing questions of metaphysics are handled with an ease and authority that amazes. An original work? Thomas saw himself as an inheritor and continuer of a tradition, but his mastery of that tradition enables him to see what others had not seen, or seen as clearly as he.
The immediate scope of this treatise is the nature of the things that are, but it also brilliantly provides a statement of a common doctrine underlying the metaphysical efforts of Greeks and Arabs, Christians and Jews, Aristotelians and Neoplatonists – a doctrine that Thomas fundamentally saw as the teaching of Aristotle.
This is a philosophical work which, on philosophical grounds, assumes that the realm of being is not limited to the things before our eyes. To ask about being, then, and what it is to be a being, and of the difference between ‘whatness’ and existence, is to open questions that move from the things of this world to God and to that great realm of beings between, what the Neoplatonists called ‘Intelligences’. Thomas calls them that here too, no doubt a quite deliberate choice on the part of a man who came to be called the Angelic Doctor, not least because of his insatiable interest in those choirs and kinds of ‘separated substances’ the Christian calls the angels.
PROLOGUE
Because a small error at the outset ends by being great, according to the Philosopher in On the Heavens 1,1 and because being and essence are what intellect first conceives, as Avicenna says in the beginning of his Metaphysics, therefore, lest ignorance of them give occasion for error, and in order to lay open the difficulty concerning them, it should be said what ‘essence’ and ‘being’ mean, how they are found in different things, and how they are related to logical intentions, namely, genus, species and difference.
We ought to derive knowledge of simple things from composite things, and come to the primary from the secondary. Since learning most fittingly comes about when we begin with easier matters, we should move from the meaning of ‘being’ to the meaning of ‘essence’.
CHAPTER 1
ON THE MEANINGS OF‘BEING’ AND‘ESSENCE’
Notice therefore that, as the Philosopher says in Metaphysics 5,1 being as such is said in two ways: first as it is divided into the ten genera, and second as meaning the truth of propositions. These differ because anything can be called being in the second sense if an affirmative proposition can be formed of it, even if it posits nothing in reality: thus privations and negations are called beings, as when we say that affirmation is opposed to negation, and that blindness exists in the eye. But in the first sense only that which posits something in reality can be called being; therefore, blindness and the like are not beings in this sense of the term.
The term essence does not apply to being in the second sense, for some things are called beings which have no essence, as is obvious in the case of privations; but essence does apply to being taken in the first sense. Hence the Commentator2 says that being in the first sense signifies the essence of the thing. And because, as has been said, being in this sense is divided into ten genera, essence must mean something common to all natures thanks to which beings are placed in the different genera and species, such that humanity is man’s essence, and similarly with other things.
Since that by which a thing is constituted in its proper genus or species is what is signified by the definition expressing what the thing is, it can be seen why philosophers changed the name essence to the name whatness, and this is what the Philosopher frequently calls that-which-it-was-to-be –namely, that through which a thing is some thing. It is also called form, insofar as form signifies the certainty of anything whatsoever, as Avicenna says in book 2 of his Metaphysics. And it is signified by yet another name, nature, taking nature in the first of the four senses that Boethius gives the term in his On the Two Natures [of Christ] – namely, anything the intellect can in any way grasp is called a nature because a thing is only intelligible through its definition and essence. The Philosopher too says in Metaphysics 51 that every substance is a nature. However, the term nature taken in this sense seems to signify the essence of a thing insofar as it is ordered to the thing’s proper activity, and nothing is without a proper activity. The name quiddity however is taken from what is signified by the definition. But essence means that through which and in which the thing has existence.
Just as being is said absolutely of substances, but only in a secondary, qualified sense of accidental qualities, the same too is true of essence. Some substances are simple and others complex. Essence is found in both, although more truly and nobly in the simple, which are the causes of the complex – at least the first simple substance, God, is. But because the essences of such substances are largely hidden from us, we must begin with the essences of complex substances, so that we might fittingly learn from more accessible concepts.
CHAPTER 2
ESSENCE IN COMPOSITE SUBSTANCES
In complex substances there are form and matter, as in man there are soul and body. Neither of these alone can be called essence. Plainly, matter alone is not essence, because a thing is knowable and also placed in a species and genus through its essence, but matter is neither a principle of knowledge nor that according to which something is characterized as to genus and species: that has to be what makes the thing actual. Nor can form alone be called the essence of complex substance, though some have sought to maintain this. It is clear from what has been said that the definition of a thing signifies its essence, but the definition of natural substance contains both form and matter, otherwise natural and mathematical definitions would not differ. Nor can it be said that matter enters into the definition of the natural substance as something added to its essence, or as outside its essence – that mode of definition is peculiar to the accidental, which, having no complete essence, requires that its subject, which is outside its genus, be put into its definition. Clearly essence comprises both matter and form.
Nor can it be said that essence signifies some relation between matter and form, or something superadded to them, since this would necessarily be an accidental quality extraneous to the thing, and the thing could not be known by means of it, as it is by its essence. It is through form, which is the act of matter, that matter is made an actual being and made to be a kind of thing. Therefore, whatever more is added, does not make matter actually to be simply speaking, but only actually to be such-and-such, which is what accidental qualities do: whiteness makes something to be actually white. That is why when such a form is acquired, a thing is not said to be generated simply speaking but only in a certain respect.
We are left, then, with this, that the word essence in the case of complex substances signifies what is composed of matter and form. This agrees with Boethius in his commentary on the Categories, where he says that ousia signifies the complex: ousia means for the Greeks what essence means for us, as he himself points out in On the Two Natures. Avicenna too says that the quiddity of complex substance is the very composition of form and matter. And the Commentator also says, with reference to Metaphysics 7. ‘The nature had by the species of generable things is something in between, that is, composed of matter and form.’
This stands to reason, since the existence of the compound substance is not of form alone nor of matter alone but of the composed thing itself; and the essence is that according to which a thing is said to exist. Necessarily then the essence whereby a thing is denominated a being cannot be form alone, nor matter alone, but is both, even though in a way only form is the cause of such existence. We see that other things constituted from several principles are not denominated from one of the principles alone but from that which comprises both. This is clear in tastes, because sweetness is caused by the heat which digests the moist, but something is not denominated sweet from heat but from taste which comprises the hot and the humid.
It might perhaps seem to follow from the fact that matter is the principle of individuation that essence cannot be defined universally, since it contains matter as well as form – particular matter, that is, not universal – and essence is what the definition signifies. But note that it is not matter understood in just any way that is the principle of individuation, but only designated matter: and I call designated matter that which is considered under determinate dimensions. Matter in this sense is not put into the definition of man as man but would be put into the definition of Socrates if Socrates had an essence. Non-designated matter is included in the definition of man, for it is not this bone and this flesh that are put into the definition of man, but bone and flesh as such which are the non-designated matter of man.
It is evident that the essence of man differs from the essence of Socrates only as the designated differs from the non-designated. Hence the Commentator says on Metaphysics 7, ‘Socrates is nothing else than animality and rationality, which are his quiddity.’ So too the essence of genus differs from that of species according to the designated and non-designated, though there is a different mode of designation than in the previous case, because the designation of the individual with reference to species is by matter with determinate dimensions, whereas the designation of species with respect to genus is by the constitutive difference taken from the form of the thing. The determination or designation in the species with reference to genus is not by way of something existing only in the essence of the species and not in the essence of the genus; indeed, whatever is in the species is also in the genus in an undetermined way. For if animal were not the whole that is man, but only its part, it would not be predicated of it, since no integral part is predicated of its whole. To see why this is so, consider that the difference between body as a part of animal and body as a genus is that body as a genus cannot be an integral part.
This term body has many meanings. In the genus of substance, body means that which has a nature such that three dimensions can be designated in it. Those three designated dimensions are body as it falls in the genus of quantity. For something that already has one perfection can receive another, as is evident in man who in addition to sensitive nature has intellectual nature. Similarly too, over and above the perfection of having a nature in which three dimensions can be designated, another perfection can be added, such as life and the like. The term body, then, can signify a thing whose form permits three dimensions to be designated in it but with precision, such that no further perfection follows from that form. If something were added, it would be outside the meaning of body in this sense. In this sense, body is an integral and material part of animal and soul is not included in its meaning but supervenes on it and from the two, body and soul, the animal is constituted as from its parts.
The term body can also be taken to signify something whose form permits three dimensions to be designated in it, whatever form that might be and whether or not any further perfection can come from it. In this sense, body is the genus of animal, because nothing should be understood in animal which is not implicitly contained in its genus body. For the soul is not a form other than the form thanks to which three dimensions can be designated in the thing. Therefore when it was said that ‘body is that which has such a form that three dimensions can be designated in it’, whatever form it has is understood, whether soul, or rock, or whatever. The animal’s form is implicitly contained in the form of body, insofar as body is its genus.
This is also the way animal relates to man. For if animal meant only something whose perfection enables it to sense and be moved by an internal principle, prescinding from other perfections, then whatever other perfection supervened would relate to animal as a co-part and not as implicitly contained in the notion of animal. Animal would not be a genus. As a genus it signifies something from whose form sense and motion can flow, whatever that form might be, whether it is sensible soul alone or both sensible and rational.
Thus genus signifies indeterminately everything that is in the species and not just matter alone. Difference signifies the whole and not form alone and the definition too signifies the whole species – but differently. For genus signifies the whole by determining what is material in the thing without the determination of its proper form; genus is taken from the matter although it is not matter. This is clear because body means that which has a perfection such that three dimensions can be designated in it, which perfection is related materially to any further perfection. Difference on the other hand is a denomination drawn from the determined form without any determinate matter being mentioned. Take the case of a thing being called animate, namely, that which has a soul; this does not tell us whether it is a body or something else. Hence Avicenna says that genus is not understood in difference as part of its essence, but only as being outside essence, as the subject is in the understanding of properties. Therefore the genus is not predicated as such of difference, the Philosopher says in Metaphysics 3 and Topics 4, but in the way that a subject is predicated of its property. The definition or species comprises both, namely the determinate matter that the genus term signifies and the determinate form that the difference term signifies.
From this it is clear why genus, species and difference relate proportionally to matter, form and the natural compound, although they are not the same as them, because the genus is not matter, but drawn from matter as signifying the whole, nor difference form, but drawn from form as signifying the whole. That is why we say that man is rational animal, and not from animal and from rational as we say he is from soul and body: for man is said to be from soul and body as a third thing constituted from two things neither of which he is, for a man is not soul nor is he body. But if man is said in some way to be constituted of animal and rational, it will not be as a third thing constituted of two things, but as a third concept composed of two concepts. For animal is conceived without the determination of any special form and expresses the nature of the thing by means of that which is material with respect to its ultimate perfection. The concept of the difference ‘rational’ consists in the determination of special form: from these two concepts is constituted the concept of species or definition. Therefore just as the constituents of a thing are not predicated of it, neither are the constituent concepts predicated of the complex concept, for we do not say that the definition is the genus or the difference.
However although genus signifies the whole essence of species, it is not necessary that there be the same essence of different species of the same genus. The unity of genus stems from this very indetermination or indifference. But what is signified by genus is not numerically the same in the different species, in which something else supervenes – namely, the difference which determines it; in much the same way numerically one form determines matter. But because genus signifies some form – though not determinately this one or that – it is the same form that difference determinately expresses and that the genus indeterminately signifies. As the Commentator says in Metaphysics 11, prime matter is called one by the removal of all forms, but genus is called one by the comprehensive universality of the form signified. Thus it is clear that the addition of difference removes the indetermination that was the cause of the unity of genus and there come into view species essentially different.
We have said that the nature of species is undetermined with respect to the individual just as genus is undetermined with respect to its species. When the genus is predicated of species it implies in its signification, though indistinctly, everything that is determinately in the species. So too species as predicated of the individual signifies all that is essential in the individual, though indistinctly. In this way the essence of species is signified by the name man, and man is predicated of Socrates. However if the nature of species were signified as prescinding from designated matter, which is the principle of individuation, then it is to take it as a part and it is signified by the name humanity; humanity signifies that whereby man is man. Designated matter is not that thanks to which man is man, and thus is not among the things whereby man is man. Clearly then, designated matter is excluded from or prescinded from in its signification. It is because the part is not predicated of the whole that humanity is not predicated of man or of Socrates. Avicenna says that the quiddity of the composed thing is not the compound of which it is the quiddity, although the quiddity itself is composed: humanity, though it is complex, is not man. Indeed, it must be received in something which is designated matter.
Because, as has been said, the designation of species with respect to genus is through form, and the designation of the individual with respect to species is through matter, it is necessary that the name signifying that whence the nature of genus is taken, prescinding from the determinate form perfecting species, signify a material part of the whole, as body is a material part of man; but the name signifying that whence the nature of species is drawn, prescinding from designated matter, signifies a formal part. Humanity therefore is signified as a form and is called the form of the whole, not as superadded to the essential parts, namely form and matter, in the way the form of house is superadded to its integral parts, but rather as the form which is the whole, namely a form comprising matter as well, although with precision from those things by which matter is designated.
Clearly then the terms ‘man’ and ‘humanity’ signify the essence of man, though differently, as has been said. ‘Man’ signifies it as a whole because it does not prescind from the designation of matter but implicitly and indistinctly contains it, much as the genus is said to contain the difference, which is why the term man is predicated of individuals. But ‘humanity’ signifies the essence as a part, because it contains in its signification only what is proper to man as man, and prescinds from every other designation: which is why it is not predicated of individual men. Because of this, the term ‘essence’ is sometimes predicated of a thing, as when we say that Socrates is a certain essence, but sometimes this is denied, as when we say that the essence of Socrates is not Socrates.
CHAPTER 3
ESSENCE AND UNIVERSALITY
Having examined what the word essence means in complex substances, we go on to ask how it relates to the notions of genus and species and difference. Because that to which the notions of genus and species and difference belong is predicated of this designated singular, it is impossible that the notion of universal – namely of genus or of species – should belong to the essence as it is signified in the manner of a part, for example, humanity or animality. That is why Avicenna said that rationality is not the difference but the principle of the difference; for the same reason, humanity is not the species nor animality the genus. Nor can it be said that the notion of genus or species belongs to essence because it is something existing apart from singulars, as the Platonists held. If that were so genus and species could not be predicated of the individual; for we cannot say that Socrates is something separated from himself or that such a separated thing would contribute to knowledge of this singular thing. It remains that the notion of genus or species belongs to essence insofar as it is signified in the manner of a whole, as by ‘man’ or ‘animal’, which implicitly and indistinctly contain everything that is in the individual.
The nature or essence so taken can be considered in two ways. In the most absolute and proper consideration of it: nothing is true of the essence except what belongs to it as such; whatever else might be attributed to it would be a false attribution. For example, ‘rational’ and ‘animal’ and the other qualities which fall under his definition belong to man insofar as he is man. White and black and such qualities, which are not part of the concept of humanity, do not belong to man as man. Can a nature so considered be called one or many? Neither, because both are outside the understanding of humanity, yet both can attach to it. For if plurality were of the very understanding of a nature, it could never be one, yet it is one in Socrates. Similarly if unity were of its notion, then it would be one and the same in Socrates and Plato, nor could it be multiplied in many individuals. In another way the essence can be considered as it exists in this or that, and thus something can be predicated of it per accidens by reason of that in which it is, as when man is said to be white because Socrates is white, although this does not belong to man insofar as he is man.
This nature can exist in two ways, however: in one way in singulars and in another way in the soul, and in both cases accidental qualities befall the nature. In singulars it has multiple existence because of the different singulars. None of this pertains to the nature itself in its first or absolute consideration. For it is false to say that it pertains to the essence of man as such to exist in this singular, for then it would never exist outside this singular; similarly if it pertained to man as man not to exist in this singular, it would never be in him. But it is true to say that man, although not just as man, is such that it is in this singular or that, or in the soul. Therefore the nature of man absolutely considered clearly abstracts from any sort of existence, but in such a way that it does not prescind from either of them. The nature considered absolutely is what is predicated of all individuals.
It cannot, however, be said that the notion of universality belongs to the nature so taken. Unity and community are of the very meaning of the universal and neither of these belongs to human nature as it is considered absolutely. For if universality were included in the understanding of man, then in whatever individual the nature were found, universality would be found. This is of course false, because there is no universality in Socrates: whatever is in him is individuated. Similarly it cannot be said that the notion of genus or species belongs to human nature as it exists in individuals. Human nature is not found in individuals as a unit common to all, which the meaning of universal requires. It follows that the notion of species belongs to human nature as it exists in the intellect.
Human nature itself exists in the intellect as abstracted from all individuating characteristics; therefore it has a uniform notion in all individuals outside the soul, because it is equally the similitude of all and conducive to the knowledge of each insofar as they are men. Because the nature has such a relation to all individuals, the intellect fashions the notion of species and attributes it to the nature. Hence the Commentator says at the beginning of the De anima that ‘it is intellect that causes universality in things’; and Avicenna says the same in his Metaphysics. And although this nature as understood has the notion of universality as it compares to things outside the soul, because it is the similitude of all, none the less insofar as it exists in this intellect or that it is a particular understood species. From this appears the defect of the Commentator in De anima 3, who wants to conclude from the universality of the form understood to the unity of the faculty of understanding in all men. But the universality of the form is not its existence in the intellect but only insofar as it refers to things as their likeness. If there were one statue representing many men, it is clear that the image or likeness of the statue has a singular and proper existence as it is in this matter, but it has the notion of community insofar as it is common to many things represented.
It pertains to human nature according to its absolute consideration to be predicated of Socrates, although the notion of species does not belong to it according to its absolute consideration but is one of the accidents that befall it as it exists in intellect. Hence species is not predicated of Socrates, as if we said, ‘Socrates is a species.’ This would necessarily happen if the notion of species belonged to man as it exists in Socrates, or according to its absolute consideration: whatever belongs to man as man is predicated of Socrates insofar as he is a man.
To be predicated belongs to genus as such, since it is part of its definition. For predication is something completed by the action of intellect composing and dividing, having as its basis in reality the unity of those things of which one is said of another. Hence the notion of predicability can be included in the notion of this intention which is the genus, which likewise is completed through the act of the intellect. Nevertheless that to which the intellect attributes the intention of predicability, joining it with another, is not itself the intention of genus, but rather that to which the intellect attributes the intention of genus, for example, to what is signified by the word animal.
Thus it is clear how essence or nature relates to the notion of species. The notion of species is not among the things which belong to the nature according to its absolute consideration, nor is it among the accidents which follow on the existence it has outside the soul, like whiteness and blackness; rather, it is among the accidents which follow on it according to the existence it has in intellect. It is in this way too that the notions of genus and difference belong to it.
CHAPTER 4
ESSENCE IN SEPARATED SUBSTANCES
It remains to be seen now how essence is found in separated substances– namely, in the soul, in intelligences and in the first cause. However, although everyone concedes the simplicity of the first cause, some seek to introduce the composition of form and matter into intelligences and in the soul. The author of this position seems to have been Avicebron, in his Fountain of Life. But this position conflicts with the common sayings of the philosophers, since they say that such substances are separated from matter and prove them to be without any matter. The most powerful demonstration of this is found in the faculty of understanding. For it is apparent that forms are actually intelligible only insofar as they are separated from matter and its conditions, and they are made actually intelligible by the power of the understanding substance insofar as they are received in it and are acted upon by it. Therefore every understanding substance must be wholly immune from matter. It has neither a material part nor is it like the material forms impressed in matter.
No one can say that intelligibility is impeded by corporeal matter alone. For if that were the case, since matter is called corporeal only insofar as it is subject to a corporeal form, it would follow that matter has the characteristic of impeding intelligibility from the corporeal form. But this cannot be, because the corporeal form itself is actually intelligible, like other forms, insofar as it is abstracted from matter. Hence in no way is there composition of matter and form in the soul or in the intelligence in such wise that essence in them would be understood as it is in corporeal substances.
But there is a composition of form and existence, hence in the comment on Proposition 9 of the Book of Causes we read that intelligence has form and existence: form meaning there the quiddity itself or the simple nature.
How this is so is easily seen. Things which are so related that one is the cause of the existence of the other are such that the cause can exist without the other, and not vice versa. But such is the relation of matter and form that form gives existence to matter; therefore it is impossible for matter to be without some form, but it is not impossible for there to besome form without matter, since form as form does not have dependence on matter. But if there are forms that can exist only in matter, this is true of them insofar as they are distant from the first principle which is first and pure act. Those forms which are closest to the first principle, accordingly, are forms as such, subsisting without matter. The entire genus of form does not require matter, as has been said; the forms which do not are called intelligences and it is not necessary that the essences or quiddities of these substances be anything other than form itself.
The essences of complex and simple substances differ in that the essence of the complex is not form alone but is composed of form and matter, whereas the essence of simple substance is form alone. Two other differences flow from this. One is that the essence of complex substance can be signified either as a whole or as a part, which befalls it on account of the designation of matter, as has been said. Therefore it is not in just any way that the essence of the complex thing is predicated of it, for it cannot be said that man is his quiddity. But the essence of the simple thing, which is its form, can be signified only as a whole, since there is nothing apart from form that might be the recipient of form; that is why the essence of the simple substance can be predicated of it. Avicenna said that ‘the quiddity of the simple is the simple thing itself’ because there is nothing else receiving it.
The second difference is that the essence of complex things, because it is received in designated matter, is multiplied according to its division. Hence it happens that some things are specifically the same and numerically different. But the essence of the simple is not received in matter, so there cannot be any multiplication of it. Nor in such substances do we find many individuals of the same species. There are as many species as there are individuals, as Avicenna expressly says.
Although they are forms alone without matter, such substances are not utterly simple nor pure act. They have a tinge of potentiality, which is clear from this – that whatever does not enter into the understanding of an essence or quiddity comes to it from without and is composed with the essence. No essence can be understood without the things that are parts of the essence. But every essence or quiddity can be understood without its existence being understood: for I can understand what a man or phoenix is and yet not know whether they exist in reality. Therefore, it is clear that to exist is other than the essence or quiddity. Unless of course there is something whose quiddity is its very existence. Such a thing is first and one, because it is impossible for there to be a multiplication of anything except by the addition of some difference, as the nature of genus is multiplied into species; either because form is received in diverse matters, as the nature of species is multiplied in diverse individuals, or because one is absolute and the other received in something, as if there were some separated heat it would be other than a non-separated heat by its very separation. If, however, there is given a thing which is existence alone, subsisting existence itself, this existence would not receive the addition of a difference, since it would not then be existence alone but existence along with some form. Much less would it receive the addition of matter, since then it would not be subsistent but material. Consequently, a thing which is its own existence can only be one, and it must be said that in every other thing its existence is one thing and its quiddity or nature or form other. In intelligences existence must be outside form, and that is why it is said that an intelligence is form and existence.
Whatever belongs to a thing is either caused by the principles of its nature, for example, risible in man; or comes to it from some extrinsic principle, as light to air from the influence of the sun. Existence cannot be caused by the form or quiddity of a thing – I mean as an efficient cause – because in this way a thing would be a cause of itself and produce itself in existence, which is impossible. Therefore it is necessary that each thing whose existence is other than its nature has its existence from another. And because whatever is from another is reduced to what is per se as to its first cause, there must be some thing which is the cause of the being of all things by the fact that it is existence alone, otherwise there would be an infinite regress in causes, since everything which is not existence alone has a cause of its existence, as has been said. It is evident then that an intelligence is form and existence, and that it has existence from the first being who is existence alone, and that this is the first cause, God.
If each thing which receives something from another is in potency to it, and what is received in it is its act, the quiddity or form that is the intelligence is in potency to the existence it receives from God, and that received existence is in the mode of an act. Thus potency and act are found in intelligences, but not form and matter except equivocally. To suffer, to receive, to be a subject, and all such qualities as are found in things by reason of matter, belong equivocally to intellectual substances and corporeal substances, as the Commentator says in De anima 3. And because the quiddity of intelligence is the intelligence itself, its quiddity or essence is identical with it and the existence it received from God is that whereby it subsists among the things that are. Because of this some say that such substances are composed of that whereby and that which, or, as Boethius says, from what is and existence.
Since potency and act are found in intelligences, it is possible to find a multitude of intelligences, as it would not be if there were no potency in them. Hence the Commentator says in De anima 3 that if the nature of the possible intellect were unknown, we would be unable to find a multitude in separated substances. Therefore the intelligences differ from one another on the basis of grade of potency and act, such that the higher intelligence, which is closer to the First Being, has more act and less potency, and so on accordingly with the others.
The human soul is the lowest level of intellectual substance and its possible intellect relates to intelligible forms as prime matter – which is the bottom of the scale of sensible being – relates to sensible forms, as the Commentator says in De anima 3. The Philosopher compares it to a tablet on which nothing has been written. Because it has more of potency than other intellectual substances, making it close to material things that they might be drawn to participate in its existence. The composition of soul and body results in one existent composite, although that existence as it pertains to soul does not depend on body. Therefore, after the soul come other forms which have more of potency and are closer to matter and which cannot exist apart from matter. Among them there are rank and order extending to the first forms of the elements which are closest to matter; hence the only operation they have follows on the demand of active and passive qualities and of other things which dispose matter for form.
CHAPTER 5
DIFFERENT BEINGS, DIFFERENT ESSENCES
In the light of the above it is clear how essence is found in different things. Essence relates to substance in three ways. First there is the one who is God, whose essence is his very existence. Indeed, because his essence is not different from his existence, some philosophers maintain that God has no quiddity or essence. It follows from this that he is not in a genus, because whatever is in a genus must have a quiddity different from its existence, since the quiddity or nature of the genus and species do not differ in their definitions in the things whose genera and species they are, although they have diverse existence in each.
Though we say that God is existence alone, we ought not to fall into the error of those who say that God is that universal existence whereby each thing formally is. A characteristic of the existence of God is that nothing can be added to it, hence it is distinct from every other existence by its own purity. That is why in the comment on Proposition 9 of the Book of Causes it is said that the individuation of the first cause, which is existence alone, is through its pure goodness. Common existence, however, is understood as neither including nor excluding addition since that would rule out the possibility of understanding it as in a being which is something besides existence.
Similarly too, although He is existence alone, He does not lack any other perfections and worthy properties. Indeed, He has all the perfections which are in all genera, thanks to which He is called simply perfect, as both the Philosopher and the Commentator say in Metaphysics 5, but He has them in a more excellent way than other things: in Him they are one, in others diverse. This is because all these perfections belong to Him according to His simple existence. If something through one quality could perform the activities of all qualities, it would have all qualities in its one quality. That is how God has all perfections in His existence.
In a second way, essence is found in created intelligences whose essence and existence differ, though their essence is without matter. Hence their existence is not absolute, but received, therefore finite and limited to the capacity of the receiving nature. Their nature or quiddity is absolute, not being received in any matter. Hence it is said in the Book of Causes that intelligences are infinite with reference to things below and finite with reference to what is above, for they are finite with respect to their existence, which they receive from above, but they are not limited downward because their forms are not limited to the capacity of any matter receiving them. As has been said, a plurality of individuals of one species is not found in such substances, except in the case of the human soul, and this because of the body with which it is united. And though its individuation depends on body opportunely by way of its beginning, since it only comes to be individuated in the body of which it is the act, it does not follow that its individuation perishes when body is subtracted. Its absolute existence is individuated by being made the form of this body, but that existence remains individuated for ever. Therefore Avicenna says that the individuation and multiplication of souls depend on body with respect to its beginning but not with respect to its end.
Because quiddity is not the same as existence in these substances, they can be placed in a category and genus and species and difference are found in them, although their proper differences are hidden from us. The essential differences of sensible things are also hidden from us, so they are signified through accidental differences which take their rise from the essential, as a cause is signified by its effect; for example, when biped is given as man’s difference. The proper accidents of immaterial substances are unknown to us so we cannot signify their differences either by essential or accidental differences.
Note too that genus and difference cannot be taken in the same way in these two kinds of substances, because in sensible substance genus is taken from that which is material in the thing and difference from that which is formal in it. Hence Avicenna says at the beginning of his On the Soul that in things composed of matter and form ‘their simple difference is constituted from it’, that is, from the form. Form itself is not the difference, but the principle of the difference, as he says in his Metaphysics. Such a difference is called the simple difference because it is taken from that which is part of the thing’s quiddity, namely its form. However, since immaterial substances are simple quiddities, in them the difference cannot be taken from a part of, but only from the whole of, quiddity. Therefore, at the beginning of On the Soul, Avicenna says that ‘only things composed of matter and form have a simple difference’.
So too in them the genus is drawn from the whole essence, but in a different way. For one separated substance is like another in immateriality, but they differ from one another in grade of perfection according to distance from potentiality and closeness to pure act. In them genus is drawn from what follows on their being immaterial, such as intellectuality or the like, whereas difference is drawn from that which follows on grade of perfection, which however is unknown to us. Nor need these differences be accidental because they are according to greater or lesser perfection, which do not diversify species: the grade of perfection in receiving the same form does not diversify species – the more or less white share in the same nature of whiteness – but the diverse grades of perfection in these participated forms or natures diversify species, as nature proceeds through grades from plant to animal through things which are intermediate between plant and animal, according to the Philosopher in On the History of Animals 8.1. Again, it is not necessary that the distinction between intellectual substances always be through two true differences, since this cannot happen with anything, as the Philosopher says in On the Parts of Animals 1.2.
In a third way essence is found in substances composed of matter and form, in which existence is received and limited because they receive existence from another and furthermore their nature or quiddity is received in designated matter. Therefore they are finite both upward and downward, and in them there can be a multiplication of individuals of the same species because of the division of designated matter. How essence relates to logical intentions in them has already been discussed.
CHAPTER 6
ESSENCE AND ACCIDENTS
Having discussed how it is found in all the kinds of substance, it remains to be seen how essence is found in accidents. Because, as has been said, essence is that which is signified by the definition, accidents will have essence in the same way that they can be defined. But they have an incomplete definition, because they can be defined only by putting their subject into the definition. This is so because they do not exist themselves apart from the subject. But just as substantial existence results from form and matter when they are composed, so accidental existence results when the accident advenes to the subject. Neither substantial form nor matter has a complete essence, because in the definition of substantial form that of which it is the form must be put, and thus its definition is by way of an addition of something outside it, as is the case with the definition of accidental form. For example, the natural philosopher who considers soul only insofar as it is a form of physical body puts body in the definition of soul.
Substantial form and accidental form differ. Substantial form does not have absolute existence in itself apart from the thing that it informs, nor does the matter to which it advenes. This is why from the conjunction of the two an existence in which a thing subsists in itself results, and something per se one is brought about as well as a certain essence. Hence form, although considered in itself it does not have the complete notion of the essence, is none the less part of the complete essence.
That to which the accident advenes is a being complete in itself, already subsisting in its own existence, and this existence naturally precedes the accident that comes to it. Therefore the supervenient accident accident – the conjunction of itself with that to which it advenes – is not the cause of the existence in which the thing subsists and by which the thing is of itself a being. Rather, it causes a secondary existence without which the subsistent thing can be understood to exist, as the first can be understood without the second. Thus, what is brought about by the composition of accident and subject is accidentally rather than per se one. Thus the accident neither has the notion of a complete essence nor is it a part of a complete essence, but it is essence in a certain respect just as it is a being in a certain respect.
Because what is especially and most truly in any genus is the cause of the other things in that genus – fire, which is the limit of heat, is the cause of heat in warm things, as is said in Metaphysics 2 – so substance, which is first in the genus of being as especially and most truly having essence, must be the cause of accidents, which secondarily and as it were in a certain respect participate in the notion of being. Which occurs variously. For since the parts of substance are matter and form, some accidents chiefly follow on form and others on matter. There is a form whose existence does not depend on matter, namely, the intellectual soul; but matter exists only through form. Hence in the accidents which follow on form there are some that do not share in matter, for example thinking, which is not by means of a bodily organ, as the Philosopher proves in On the Soul 3, and others that do share in matter, for example sensing. But there is no accident following on matter that does not share in matter.
A certain diversity is found among the accidents which follow on matter. For some accidents follow on matter according to an ordering they have to a special form, such as masculine and feminine in animals, a diversity reducible to matter, as is said in Metaphysics 10. Hence, the form of animal being taken away, such accidents remain only equivocally. Others follow on matter according to an ordering to a general form, and these remain when the special form is taken away, as black pigment is in the Ethiopian from a mixture of elements and not by reason of soul, and therefore after death it remains.
Because a thing is individuated by matter and placed in a genus or species because of its form, the accidents which follow on matter are accidents of the individual, according to which members of the same species differ among themselves. The accidents which follow on form are properties of either genus or species and thus are found in everything which shares in the nature of the genus or species, as risible follows on man’s form, since laughter is occasioned by some awareness in man’s soul.
It should also be noted that accidents in full actuality are sometimes caused by the essential principles, like the heat in fire which is always hot, but sometimes only in aptitude such that they are completed by an external agent, as the diaphaneity of air is completed by the external luminous body. In the latter, the aptitude is an inseparable accident, but the completion that comes from a principle outside the essence of the thing, or which does not enter into the constitution of the thing, is separable, for example to be moved and the like.
It should further be noted that genus, difference and species are understood in accidents differently than they are in substances. From the coming together of substantial form and matter something in itself one results which is properly placed in the category of substance. In substances concrete names which signify the composite are properly said to be in a species or genus, for example, man or animal. Neither form nor matter is in a category in this way, save by way of reduction, as principles are said to be in a genus. Nothing in itself one comes to be from accident and subject; hence from their conjunction no nature results to which the intention of genus or species could be attributed. Hence accidental terms expressed concretely, like white or musical, are not put into a category as species or genera except by reduction, but only as abstractly expressed, like whiteness and music. And since accidents are not composed of matter and form, in them genus cannot be taken from matter or difference from form as they are in composed substances. Genus must first be taken from their very mode of being, insofar as being is said diversely, according to prior and posterior, of the ten genera of category. Thus the definition of quantity is that it is the measure of substance and quality that it is a disposition of substance, and so with the rest, according to the Philosopher in Metaphysics 9.
Differences in them are taken from the diversity of principles from which they are caused. And because properties are caused by the proper principles of the subject, the subject is put in their definition in the place of difference, if they are abstractly defined – which is how they are properly in a genus – for example, snubness is defined as the curvature of the nose. It is otherwise when they are defined as concretely expressed, for then the subject is put into the definition as the genus, because they would then be defined after the manner of composed substances in which the notion of genus is drawn from matter, for example we say that snub is a curved nose. It is similar when one accident is the principle of another, as action and passion and quantity are principles of relation, and thus it is with reference to these that the Philosopher subdivides relation in Metaphysics 5. However, because the proper principles of accidents are not always manifest, sometimes we take the differences of accidents from their effects, such as dispersion or concentration produces differences of colour, insofar as there is an abundance or paucity of light, from which the different species of colour are caused.
Thus it is clear how essence is found in substance and accident and in complex and simple substance, and how in all these the intentions of universality are logically found – except the First, in whom there is full simplicity and to whom neither the notion of genus and species nor consequently definition belongs because of His simplicity. And that is the end and completion of this discourse. Amen.