Medieval Sourcebook:
Thomas Aquinas:
On Being and Essence (DE ENTE Et ESSENTIA)
DE ENTE ET ESSENTIA [[1]]
Translation © 1997 by Robert T.
Miller[[2]]
Prologue
A small error at the outset can lead to great errors in the final
conclusions, as the Philosopher says in I De Caelo et Mundo cap. 5 (271b8-13), and thus, since being and essence are the things
first conceived of by the intellect, as Avicenna says in Metaphysicae I, cap. 6, in order to avoid errors arising from ignorance about
these two things, we should resolve the difficulties surrounding
them by explaining what the terms being and essence each signify
and by showing how each may be found in various things and how
each is related to the logical intentions of genus, species, and
difference.
Since we ought to acquire knowledge of simple things from composite
ones and come to know the prior from the posterior, in instructing
beginners we should begin with what is easier, and so we shall
begin with the signification of being and proceed from there to
the signification of essence.
Chapter 1
As the Philosopher says in V Metaphysicae cap. 7 (1017a22-35),
being has two senses. In one sense, being signifies that which
is divided into the ten categories; in another sense, that which
signifies the truth of propositions. The difference between these
is that, in the second sense, anything can be called a being about
which an affirmative proposition can be formed, even if the thing
posits nothing in reality. In this way, privations and negations
are called beings, as when we say that affirmation is opposed
to negation, or that blindness is in the eye. But in the first
sense, nothing can be called a being unless it posits something
in reality, and thus in this first sense blindness and similar
things are not beings.
The term essence is not taken from being in the second sense,
for in this sense some things are called beings that have no essence,
as is clear with privations. Rather, the term essence is taken
from being in the first sense. Thus in Metaphysicae V,
com. 14, the Commentator explains the cited text from Aristotle
by saying that being, in the first sense, is what signifies the
essence of a thing. And since, as said above, being in this sense
is divided into the ten categories, essence signifies something
common to all natures through which the various beings are placed
in the various genera and species, as humanity is the essence
of man, and so on.
Since that through which a thing is constituted in its proper
genus or species is what is signified by the definition indicating
what the thing is, philosophers introduced the term quiddity to
mean the same as the term essence; and this is the same thing
that the Philosopher frequently terms what it is to be a thing,
that is, that through which something has being as a particular
kind of thing. Essence is also called form, for the certitude
of every thing is signified through its form, as Avicenna says
in his Metaphysicae I, cap. 6. The same thing is also called
nature, taking nature in the first of the four senses that Boethius
distinguishes in his book De Persona et Duabus Naturis cap. 1 (PL 64, 1341B), in the sense, in other words, that nature
is what we call everything that can in any way be captured by
the intellect, for a thing is not intelligible except through
its definition and essence. And so the Philosopher says in V Metaphysicae cap. 4 (1014b36) that every substance is a nature. But the term
nature used in this way seems to signify the essence of a thing
as it is ordered to the proper operation of the thing, for no
thing is without its proper operation. The term quiddity, surely,
is taken from the fact that this is what is signified by the definition.
But the same thing is called essence because the being has existence
through it and in it.
But because being is absolutely and primarily said of substances,
and only secondarily and in a certain sense said of accidents,
essence too is properly and truly in substances and is in accidents
only in a certain way and in a certain sense. Now some substances
are simple and some are composite, and essence is in both, though
in the simple substances in a truer and more noble way, as these
have existence in a nobler way: indeed, the simple substances
are the cause of the composite ones, or at least this is true
with respect to the first simple substance, which is God. But
because the essences of these substances are more hidden from
us, we ought to begin with the essences of composite substances,
as learning is easier when we begin with the easier things.
Chapter II
In composite substances we find form and matter, as in man there
are soul and body. We cannot say, however, that either of these
is the essence of the thing. That matter alone is not the essence
of the thing is clear, for it is through its essence that a thing
is knowable and is placed in a species or genus. But matter is
not a principle of cognition; nor is anything determined to a
genus or species according to its matter but rather according
to what something is in act. Nor is form alone the essence of
a composite thing, however much certain people may try to assert
this. From what has been said, it is clear that the essence is
that which is signified by the definition of the thing. The definition
of a natural substance, however, contains not only form but also
matter; otherwise, the definitions of natural things and mathematical
ones would not differ. Nor can it be said that matter is placed
in the definition of a natural substance as something added to
the essence or as some being beyond the essence of the thing,
for that type of definition is more proper to accidents, which
do not have a perfect essence and which include in their definitions
a subject beyond their own genus. Therefore, the essence clearly
comprises both matter and form.
Nor can it be said that essence signifies the relation between
the matter and the form or something superadded to these, for
then the essence would of necessity be an accident and extraneous
to the thing, and the thing would not be known through its essence,
contrary to what pertains to an essence. Through the form, surely,
which is the act of the matter, the matter is made a being in
act and a certain kind of thing. Thus, something that supervenes
does not give to the matter existence in act simply, but rather
existence in act in a certain way, just as accidents do, as when
whiteness makes something actually white. Hence, when such a form
is acquired, we do not say that the thing is generated simply
but only in a certain way.
The only possibility, therefore, is that the term essence, used
with respect to composite substances, signifies that which is
composed of matter and form. This conclusion is consistent with
what Boethius says in his commentary on the Categories,
namely, that ousia signifies what is composite; ousia,
of course, is for the Greeks what essence is for us, as Boethius
himself says in his book De Persona et Duabus Naturis.[[3]] Avicenna even says, Metaphysicae V, cap. 5, that the quiddity
of a composite substance is the very composition of the form and
the matter. And commenting on Book VII of Aristotle's Metaphysicae,
the Commentator says, "The nature that species in generable
things have is something in the middle; that is, it is composed
of matter and form." Metaphysicae VII, com. 27. Moreover,
reason supports this view, for the existence of a composite substance
is neither form alone nor matter alone but is rather composed
of these. The essence is that according to which the thing is
said to exist; hence, it is right that the essence by which a
thing is denominated a being is neither form alone not matter
alone but both, albeit that existence of this kind is caused by
the form and not by the matter. Similarly, we see that in other
things that are constituted from many principles, the thing is
not denominated from just one or the other of the principles but
rather from that which embraces both. Thus, with respect to flavors,
sweetness is caused by the action of a warm animal body digesting
what is wet, and albeit that in this way warmth is the cause of
the sweetness, nevertheless a body is not called sweet by reason
of the warmth, but rather by reason of the flavor, which embraces
both the warmth and the wetness.
But because matter is the principle of individuation, it would
perhaps seem to follow that essence, which embraces in itself
simultaneously both form and matter, is merely particular and
not universal. From this it would follow that universals have
no definitions, assuming that essence is what is signified by
the definition. Thus, we must point out that matter understood
in the way we have thus far understood it is not the principle
of individuation; only signate matter is the principle of individuation.
I call signate matter matter considered under determinate dimensions.
Signate matter is not included in the definition of man as man,
but signate matter would be included in the definition of Socrates
if Socrates had a definition. In the definition of man, however,
is included non-signate matter: in the definition of man we do
not include this bone and this flesh but only bone and flesh absolutely,
which are the non-signate matter of man.
Hence, the essence of man and the essence of Socrates do not differ
except as the signate differs from the non-signate, and so the
Commentator says, in Metaphysicae VII, com. 20, "Socrates
is nothing other than animality and rationality, which are his
quiddity." Similarly, the essence of a genus and the essence
of a species differ as signate from non-signate, although in the
case of genus and species a different mode of designation is used
with respect to both. For, the designation of the individual with
respect to the species is through matter determined by dimensions,
while the designation of the species with respect to the genus
is through the constitutive difference, which is taken from the
form of the thing. This determination or designation, however,
which is made in the species with respect to the genus, is not
through something that exists in the essence of the species but
in no way exists in the essence of the genus. On the contrary,
whatever is in the species is also in the genus as undetermined.
If animal were not all that man is but rather only a part of him,
then animal would not be predicated of man, for no integral part
is predicated of its whole.
We can see how this happens by considering how body as a part
of animal differs from body as the genus of animal. In the way
body is the genus of animal it cannot be an integral part of animal,
and thus the term body can be accepted in several ways. Body is
said to be in the genus of substance in that it has a nature such
that three dimensions can be designated in the body. These three
designated dimensions are the body that is in the genus of quantity.
Now, it sometimes happens that what has one perfection may attain
to a further perfection as well, as is clear in man, who has a
sensitive nature and, further, an intellective one. Similarly,
above this perfection of having a form such that three dimensions
can be designated in it, there can be joined another perfection,
as life or some similar thing. This term body, therefore, can
signify a certain thing that has a form such that from the form
there follows in the thing designatability in three dimensions
and nothing more, such that, in other words, from this form no
further perfection follows, but if some other thing is superadded,
it is beyond the signification of body thus understood. And understood
in this way, body will be an integral and material part of the
animal, because in this way the soul will be beyond what is signified
by the term body, and it will supervene on the body such that
from these two, namely the soul and the body, the animal is constituted
as from parts.
This term body can also be understood as signifying a certain
thing that has a form such that three dimensions can be designated
in it, whatever form this may be, and such that either from the
form some further perfection can proceed or not. Understood in
this way, body will be the genus of animal, for there will be
understood in animal nothing that is not implicitly contained
in body. Now, the soul is a form through which there can be designated
in the thing three dimensions, and therefore, when we say that
body is what has a form from which three dimensions can be designated
in the body, we understand there is some kind of form of this
type, whether soul, or lapideousness, or whatever other form.
And thus the form of animal is implicitly contained in the form
of body, just as body is its genus.
The relation of animal to man is the same. For if animal named
just a certain thing that has a perfection such that it can sense
and move by a principle existing in itself, without any other
perfection, then whatever further perfection may supervene would
be related to animal as a component part, and not as implicitly
contained in the notion of animal; and in this way animal would
not be a genus. But animal is a genus in that it signifies a certain
thing from the form of which sensation and motion can proceed,
whatever this form may be, whether a sensible soul only, or a
soul both sensible and rational.
Therefore, the genus signifies indeterminately the whole that
is in the species and does not signify matter alone. Similarly,
the difference also signifies the whole and does not signify the
form alone, and the definition, or even the species, signifies
the whole. But these nevertheless signify the same thing in different
ways. For the genus signifies the whole as a certain denomination
determining that which is material in the thing without a determination
of its proper form, whence the genus is taken from the matter,
although it is not the matter. This is clear in the case of bodies,
as we call something a body in that the thing has a perfection
such that in the thing three dimensions can be designated, and
this perfection is related materially to some further perfection.
Conversely, the difference is like a certain denomination taken
from the determined form, beyond the first conception of the form
by which the matter is determined. So, when we say something is
animated (that, in other words, it has a soul), this does not
determine what the thing is, whether it is a body or some other
thing. Hence, Avicenna says, Metaphysicae V, cap. 6, that
the genus is not understood in the difference as a part of its
essence but only as a being beyond its essence, even as a subject
is with respect to the concept of a passion. And thus the genus
is not predicated per se of the difference, as the Philosopher
says in III Metaphysicae cap. 8 (998b24) and in IV Topicorum cap. 2 (122b22-26), unless perhaps as a subject is predicated
of a passion. But the definition or the species comprehends both,
namely, the determined matter that the term genus designates and
the determined form that the term difference designates.
From this is it clear why the genus, the difference, and the species
are related proportionally to the matter, the form, and the composite
in nature, although they are not the same as these things. For,
the genus is not the matter, though it is taken from the matter
as signifying the whole; nor is the difference the form, though
it is taken from the form as signifying the whole. Thus we say
that man is a rational animal, but not composed of the animal
and the rational in the sense that we say that man is composed
of soul and body: man is said to be composed of soul and body
as from two things from which a third thing is constituted different
from each of the two. Man, surely, is neither body nor soul. But
if man is said in some sense to be composed of the animal and
the rational, it will not be as a third thing composed from these
two things, but as a third concept composed from these two concepts.
The concept of animal is without determination of a special form
and expresses, with respect to the ultimate perfection, the nature
of the thing from that which is material; the concept of the difference,
rational, consists in the determination of the special form. From
these two concepts are constituted the concept of the species
or the definition. Thus, just as a thing constituted from other
things does not have predicated of it these other things, so too
a concept does not have predicated of it the concepts of which
it is constituted: clearly, we do not say that the definition
is either the genus or the difference.
Although the genus may signify the whole essence of the species,
nevertheless there is not just one essence of the various species
under one genus, for the unity of the genus proceeds from its
very indetermination or undifferentiation. Nor is it the case
that what is signified through the genus is numerically one nature
in the various species such that to it there supervenes some other
thing, which is the difference that determines it, as a form determines
matter, which is numerically one. Rather, the genus signifies
some form (though not determinately this one or that one), which
the difference expresses determinately, the very one that is signified
indeterminately through the genus. And thus the Commentator says
in Metaphysicae XII, [[4]] com. 14, that prime matter is called one by the removal of all
forms, but the genus is called one through the commonality of
forms signified. Hence, the indetermination, which was the cause
of the unity of the genus, having been removed through the addition
of the difference, the species remain essentially diverse.
Furthermore, since, as said above, 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, and since, further,
the genus, as predicated of the species, includes in its signification
(although indistinctly) everything that is in the species determinately,
so too does the species, as predicated of the individual, signify
everything that is in the individual essentially, although it
signifies this indistinctly. In this way, the essence of the species
is signified by the term man, and so man is predicated of Socrates.
If, however, the nature of the species is signified in such a
way as to exclude designate matter, which is the principle of
individuation, then the species is related to the individual as
a part; and this is how the term humanity signifies, for humanity
signifies that by which a man is a man. Designate matter, however,
is not that by which a man is a man, and it is in no way contained
among those things that make a man a man. Since, therefore, the
concept of humanity includes only those things by which a man
is a man, designate matter is excluded or pretermitted, and since
a part is not predicated of its whole, humanity is predicated
neither of man nor of Socrates. Thus Avicenna says, Metaphysicae V, cap. 5, that the quiddity of a composite thing is not the composite
thing of which it is the quiddity, even though the quiddity itself
is composite, as humanity, while composite, is not man. On the
contrary, it must be received in something that is designate matter.
But since, as said above, the designation of the species with
respect to the genus is through the form, and the designation
of the individual with respect to the species is through matter,
the term signifying that from which the nature of the genus is
taken thus excludes the determinate form that completes the species
and signifies the material part of the whole, as the body is the
material part of the man. However, the term signifying that from
which the nature of the species is taken, excluding designate
matter, signifies the formal part. Thus, humanity is signified
as a certain form, and it is said that it is the form of the whole,
not, certainly, as a form superadded to the essential parts (the
form and the matter), but rather as the form of a house is superadded
to its integral parts; and that is better called the form which
is the whole, in other words, that which embraces the form and
the matter, albeit excluding those things through which the designatability
of matter arises.
Therefore, the term man and the term humanity both signify the
essence of man, though in diverse ways, as said above. The term
man signifies the essence as a whole, in other words, insofar
as the essence does not exclude designation of matter but implicitly
and indistinctly contains it, in the way in which we said that
the genus contains the difference. Hence, the term man is predicated
of individuals. But the term humanity signifies the essence of
man as a part because it contains in its signification only what
belongs to man insofar as he is man, and it excludes all designation,
and so it is not predicated of individual men. And for this reason
the term essence is sometimes found predicated of the thing, as
when we say that Socrates is a certain essence; and sometimes
the term essence is denied of the thing, as when we say that the
essence of Socrates is not Socrates.
Chapter III
Having seen what the term essence signifies in composite substances,
we ought next see in what way essence is related to the logical
intentions of genus, species, and difference. Since that to which
the intentions of genus or species or difference is appropriate
is predicated of this signate singular, it is impossible that
a universal intention, like that of the species or genus, should
be appropriate to the essence if the genus or species is signified
as a part, as in the term humanity or animality. Thus, Avicenna
says, Metaphysicae V, cap. 6, that rationality is not the
difference but the principle of the difference. For the same reason,
humanity is not a species, and animality is not a genus. Similarly,
we cannot say that the intention of species or genus is appropriate
to the essence as to a certain thing existing beyond singulars,
as the Platonists used to suppose, for then the species and the
genus would not be predicated of an individual: we surely cannot
say that Socrates is something that is separated from him, nor
would that separate thing advance our knowledge of this singular
thing. And so the only remaining possibility is that the intention
of genus or species is appropriate to the essence as the essence
is signified as a whole, as the term man or animal implicitly
and indistinctly contains the whole that is in the individual.
The nature, however, or the essence thus understood can be considered
in two ways. First, we can consider it according to its proper
notion, and this is to consider it absolutely. In this way, nothing
is true of the essence except what pertains to it absolutely:
thus everything else that may be attributed to it will be attributed
falsely. For example, to man, in that which he is a man, pertains
animal and rational and the other things that fall in his definition;
white or black or whatever else of this kind that is not in the
notion of humanity does not pertain to man in that which he is
a man. Hence, if it is asked whether this nature, considered in
this way, can be said to be one or many, we should concede neither
alternative, for both are beyond the concept of humanity, and
either may befall the conception of man. If plurality were in
the concept of this nature, it could never be one, but nevertheless
it is one as it exists in Socrates. Similarly, if unity were in
the notion of this nature, then it would be one and the same in
Socrates and Plato, and it could not be made many in the many
individuals. Second, we can also consider the existence the essence
has in this thing or in that: in this way something can be predicated
of the essence accidentally by reason of what the essence is in,
as when we say that man is white because Socrates is white, although
this does not pertain to man in that which he is a man.
The nature considered in this way, however, has a double existence.
It exists in singulars on the one hand, and in the soul on the
other, and from each of these there follow accidents. In singulars,
furthermore, the essence has a multiple existence according to
the multiplicity of singulars. Nevertheless, if we consider the
essence in the first, or absolute, sense, none of these pertain
to the essence. For it is false to say that the essence of man,
considered absolutely, has existence in this singular, because
if existence in this singular pertained to man insofar as he is
man, man would never exist outside this singular. Similarly, if
it pertained to man insofar as he is man not to exist in this
singular, then the essence would never exist in the singular.
But it is true to say that man, but not insofar as he is man,
has whatever may be in this singular or in that one, or else in
the soul. Therefore, the nature of man considered absolutely abstracts
from every existence, though it does not exclude the existence
of anything either. And the nature thus considered is the one
predicated of each individual.
Nevertheless, the nature understood in this way is not a universal
notion, because unity and commonality are in the notion of a universal,
and neither of these pertains to human nature considered absolutely.
For if commonality were in the concept of man, then in whatever
humanity were found, there would be found commonality, and this
is false, because no commonality is found in Socrates, but rather
whatever is in him is individuated. Similarly, the notion of genus
or species does not pertain to human nature as an accident arising
from the existence that the nature has in individuals, for human
nature is not found in individuals according to its unity such
that it will be one thing in all the individuals, which the notion
of the universal demands. The only possibility, therefore, is
that the notion of species pertains to human nature according
to the existence human nature has in the intellect.
Human nature has in the intellect existence abstracted from all
individuals, and thus it is related uniformly to all individuals
that exist outside the soul, as it is equally similar to all of
them, and it leads to knowledge of all insofar as they are men.
Since the nature in the intellect has this relation to each individual,
the intellect invents the notion of species and attributes it
to itself. Hence, the Commentator, in De Anima I, com.
8, says, "The intellect is what makes universality in things,"
and Avicenna says the same in his Metaphysicae V, cap.
2. Although this nature understood in the intellect has the notion
of a universal in relation to things outside the soul (because
it is one likeness of them all), as the nature has existence in
this intellect or in that one, it is a certain particular understood
species. The Commentator, therefore, is in error in De Anima III, com. 5, when he wants to infer the unity of intellect in
all men from the universality of the understood form, because
the universality of the form does not arise from the existence
the form has in the intellect but rather from its relation to
things as a likeness of such things. It is as if there were a
corporeal statue representing many men; that image or species
of statue would have a singular and proper existence insofar as
it exists in this matter, but it would have an aspect of commonality
insofar as it was a common representative of many.
Since human nature, considered absolutely, is properly predicated
of Socrates, and since the notion of species does not pertain
to human nature considered absolutely but only accidentally because
of the existence the nature has in the intellect, the term species
is not predicated of Socrates, for we do not say that Socrates
is a species. We would have to say that Socrates is a species
if the notion of species pertained to man arising from the existence
that the nature has in Socrates or from the nature considered
absolutely, that is, insofar as man is man. For whatever pertains
to man insofar as he is man is predicated of Socrates.
But to be predicated pertains to a genus per se, because being
predicated is placed in its definition. Now, predication is completed
by the action of the intellect in compounding and dividing, and
it has as its basis the unity of those things one of which is
said of another. Hence, the notion of predicability can be subsumed
in the notion of this intention that is the genus, which is itself
completed by an act of the intellect. Still, when the intellect
attributes the intention of predicability to something by compounding
it with another, this intention is not that of genus; it is rather
that to which the intellect attributes the intention of genus,
as, for instance, to what is signified by the term animal.
We have thus made clear how the essence or nature is related to
the notion of species, for the notion of species is not among
those that pertain to the essence considered absolutely; nor is
it among the accidents that follow from the existence that the
essence has outside the soul, as whiteness or blackness. Rather,
the notion of species is among the accidents that follow from
the existence the essence has in the intellect. And in this way
as well do the notions of genus or difference pertain to essences.
Chapter IV
We should now see how essences exist in separated substances,
that is, in the soul, in the intelligences, and in the first cause.
Now, while everyone concedes the simplicity of the first cause,
some people have tried to introduce into the intelligences and
the soul a composition of form and matter, a position that seems
to have begun with Avicebron, the author of the book called Fons
Vitae. But this view is repugnant to the common teaching of
the philosophers, for they call these things substances separated
from matter, and they prove them to be wholly without matter.
The most cogent demonstration of this proceeds from the excellence
of understanding found in these substances. For we see that forms
are not actually intelligible except as they are separated from
matter and its conditions, and forms are not made actually intelligible
except by virtue of an intelligent substance, which educes the
forms and receives them in itself. Hence, in any intelligent substance
there is a complete absence of matter in such a way that the substance
has neither a material part itself nor even is the substance like
a form impressed in matter, as is the case with material forms.
Nor can someone say that only corporeal matter, and not some other
kind of matter, impedes intelligibility. For, if it were only
corporeal mater that impedes intelligibility, then since matter
is called corporeal only insofar as it exists under a corporeal
form, matter's impeding intelligibility would come from the corporeal
form; and this is impossible, for the corporeal form is actually
intelligible just like any other form, insofar as it is abstracted
from matter. Hence, in no way is there a composition of matter
and form in either the soul or the intelligences, such that an
essence is received in these as in corporeal substances. Nevertheless,
in separate substances there is a composition of form and existence,
and so in the Liber de Causis, prop. 9, com., it is said
that the intelligences have form and existence, and in this place
form is taken in the sense of a simple quiddity or nature.
It is easy to see how this is the case. Whenever two things are
related to each other such that one is the cause of the other,
the one that is the cause can have existence without the other,
but not conversely. Now, we find that matter and form are related
in such a way that form gives existence to matter, and therefore
it is impossible that matter exist without a form; but it is not
impossible that a form exist without matter, for a form, insofar
as it is a form, is not dependent on matter. When we find a form
that cannot exist except in matter, this happens because such
forms are distant from the first principle, which is primary and
pure act. Hence, those forms that are nearest the first principle
are subsisting forms essentially without matter, for not the whole
genus of forms requires matter, as said above, and the intelligences
are forms of this type. Thus, the essences or quiddities of these
substances are not other than the forms themselves.
Therefore, the essence of a composite substance and that of a
simple substance differ in that the essence of a composite substance
is not form alone but embraces both form and matter, while the
essence of a simple substance is form alone. And from this two
other differences arise. One is that the essence of a composite
substance can be signified as a whole or as a part, which happens
because of the designation of the matter, as said above. Hence,
in one way, the essence of a composite thing is not predicated
of the composite thing itself, for we cannot say that a man is
his own quiddity. But the essence of a simple thing, which is
its form, cannot be signified except as a whole, as in this case
there is nothing beyond the form that might receive the quiddity,
and so, however we take the essence of a simple thing, the essence
is predicated of it. Hence, Avicenna says in Metaphysicae V, cap. 5 that "the quiddity of a simple thing is the simple
thing itself," because there is no other thing to receive
the form. The second difference is that the essences of composite
things, because they are received in designate matter, are multiplied
according to the division of matter, and so it happens that some
things are the same in species but different in number. But since
the essence of a simple thing is not received in matter, there
can be no such multiplication in this case, and so among such
substances we do not find many individuals of the same species,
as Avicenna expressly says in Metaphysicae V, cap. 2.
Although substances of this kind are form alone and are without
matter, they are nevertheless not in every way simple, and they
are not pure act; rather, they have an admixture of potency, and
this can be seen as follows. Whatever is not in the concept of
the essence or the quiddity comes from beyond the essence and
makes a composition with the essence, because no essence can be
understood without the things that are its parts. But every essence
or quiddity can be understood without understanding anything about
its existence: I can understand what a man is or what a phoenix
is and nevertheless not know whether either has existence in reality.
Therefore, it is clear that existence is something other than
the essence or quiddity, unless perhaps there is something whose
quiddity is its very own existence, and this thing must be one
and primary. For, there can be no plurification of something except
by the addition of some difference, as the nature of a genus is
multiplied in its species; or as, since the form is received in
diverse matters, the nature of the species is multiplied in diverse
individuals; or again as when one thing is absolute and another
is received in something else, as if there were a certain separate
heat that was other than unseparated heat by reason of its own
separation. But if we posit a thing that is existence only, such
that it is subsisting existence itself, this existence will not
receive the addition of a difference, for, if there were added
a difference, there would be not only existence but existence
and also beyond this some form; much less would such a thing receive
the addition of matter, for then the thing would be not subsisting
existence but material existence. Hence, it remains that a thing
that is its own existence cannot be other than one, and so in
every other thing, the thing's existence is one thing, and its
essence or quiddity or nature or form is another. In the intelligences,
therefore, there is existence beyond the form, and so we say that
an intelligence is form and existence.
Everything that pertains to a thing, however, either is caused
by the principles of its own nature, as risibility in man, or
else comes from some extrinsic principle, as light in the air
from the influence of the sun. Now, it cannot be that existence
itself is caused by the very form or quiddity of the thing (I
mean as by an efficient cause), because then the thing would be
its own efficient cause, and the thing would produce itself in
existence, which is impossible. Therefore, everything the existence
of which is other than its own nature has existence from another.
And since everything that is through another is reduced to that
which is through itself as to a first cause, there is something
that is the cause of existing in all things in that this thing
is existence only. Otherwise, we would have to go to infinity
in causes, for everything that is not existence alone has a cause
of its existence, as said above. It is clear, therefore, that
the intelligences are form and existence and have existence from
the first being, which is existence alone, and this is the first
cause, which is God.
Everything that receives something from another is in potency
with respect to what it receives, and that which is received in
the thing is its act; therefore, a quiddity or form that is an
intelligence is in potency with respect to the existence that
it receives from God, and this received existence is received
as its act. And thus there are found in the intelligences both
potency and act but not matter and form, unless in some equivocal
sense. So too to suffer, to receive, to be a subject and everything
of this type that seem to pertain to things by reason of their
matter are said of intellectual substances and corporeal substances
equivocally, as the Commentator says in De Anima III, com.
14. Furthermore, since, as said above, the quiddity of an intelligence
is the intelligence itself, its quiddity or essence is itself
the very thing that exists, and its existence received from God
is that by which it subsists in the nature of things; and because
of this some people say that substances of this kind are composed
of what is and that by which it is, or of what is and existence,
as Boethius says in De Hebdomadibus (PL 64, 1311 B-C).
Moreover, since we posit in the intelligences potency and act,
it will not be difficult to find a multitude of intelligences,
which would be impossible if there were in them no potency. Hence,
the Commentator says in De Anima III, com. 5 that if the
nature of the possible intellect were unknown, we would not be
able to find a multitude of separate substances. There is thus
a distinction among separate substances according to their grade
of potency and act such that the superior intelligences, which
are nearer the first cause, have more act and less potency, and
so on.
This scale comes to an end with the human soul, which holds the
lowest place among intellectual substances. The soul's possible
intellect is related to intelligible forms just as prime matter
(which holds the lowest place in sensible existence) is related
to sensible forms, as the Commentator says in De Anima III, com. 5. The Philosopher thus compares, III De Anima cap. 4 (430a1), the soul to a tablet on which nothing has been
written. Since, among intellectual substances, the soul has the
most potency, it is so close to material things that a material
thing is brought to participate in its existence: that is, from
the soul and the body there results one existence in one composite
thing, although this existence, as the existence of the soul,
is not dependent on the body. Therefore, beyond this form that
is the soul, there are other forms having more potency and being
closer to matter, and so much so that they have no existence without
matter. Among these forms there is an order and gradation down
to the primary forms of the elements, which are closest to matter;
and so these have no operation except as required by the active
and passive qualities and other such qualities by which matter
is disposed by form.
Chapter V
Having treated these matters, we can see clearly how essence is
found in various kinds of things. There are three ways in which
substances may have an essence. First, surely, is the way God
has his essence, which is his very existence itself, and so we
find certain philosophers saying that God does not have a quiddity
or essence because his essence is not other than his existence.
From this it follows that he is not in a genus, for everything
that is in a genus has a quiddity beyond its existence, since
the quiddity or nature of the genus or species is not in the order
of nature distinguished in the things of which it is the genus
or species, but the existence is diverse in diverse things.
Even though we say that God is existence alone we do not fall
into the error of those who said that God is that universal existence
by which everything formally exists. The existence which is God
is of such a kind that no addition can be made to it, whence through
its purity it is distinct from every other existence; for this
reason the author of the Liber de Causis, prop. 9, com.,
says that the individuation of the first cause, which is being
alone, is through its pure goodness. But common existence, just
as it does not include in its concept any addition, so too in
its concept does it not exclude any addition; for, if such existence
did in its concept exclude any addition, nothing could be understood
to exist in which there was added something beyond existence.
Similarly, although God is existence alone, the remaining perfections
and nobilities are not lacking in him. On the contrary, he has
all the perfections that exist in every genus, and for this reason
he is called perfect without qualification, as the Philosopher,
V Metaphysicae cap. 16 (1021b30-33), and the Commentator, Metaphysicae V, com. 21, each say. But God has these perfections
in a more excellent way than all other things have them because
in him they are one, while in other things they are diverse. And
this is because all these perfections pertain to God according
to his simple existence, just as, if someone through one quality
could effect the operations of all qualities, such a person would
have in that one quality all the qualities, so too does God in
his very existence have all the perfections.
In a second way, essence is found in created intellectual substances,
in which existence is other than essence, although in these substances
the essence is without matter. Hence, their existence is not absolute
but received, and so finite and limited by the capacity of the
receiving nature; but their nature or quiddity is absolute and
is not received in any matter. Thus, the author of the Liber
de Causis, prop. 16, com., says that intelligences are infinite
in an inferior way and finite in a superior way: they are finite
with respect to their existence, which they receive from something
superior, though they are not rendered finite in an inferior way
because their forms are not limited to the capacity of some matter
receiving them. And thus among such substances we do not find
a multitude of individuals in one species, as said above, except
in the case of the human soul, and there we do find a multitude
of individuals in one species because of the body to which the
soul is united. Now, the individuation of the soul depends on
the body, in an occasional manner, as to its inception, for the
soul does not acquire for itself individual existence unless in
the body of which it is the act. But nevertheless, if we subtract
the body, the individuation does not perish because, since the
soul was made the form of a given body, the form has absolute
existence from which it has acquired individuated existence, and
this existence always remains individuated. And thus Avicenna
says, De Anima V, cap. 3, that the individuation of souls
and their multiplication depend on the body for their beginning
but not for their end.
Since in these substances the quiddity is not the same as existence,
these substances can be ordered in a predicament, and for this
reason we find among these things genera, species, and differences,
although their proper differences are hidden from us. In sensible
things even the essential differences are unknown to us, and so
they are signified through accidental differences that arise from
the essential ones, just as a cause is signified through its effect.
We take bipedality, for example, as the difference of man. The
proper accidents of immaterial substances, however, are unknown
to us, and thus we can signify their differences neither per se
nor through their accidental differences.
We should note, though, that the genus and difference in immaterial
substances are not taken in the same way as in sensible substances,
for in sensible substances the genus is taken from that which
is material in the thing, while the difference is taken from that
which is formal in the thing. Hence, Avicenna says, De Anima I, cap.1, that, in things composed of form and matter, the form
"is its simple difference because the thing is constituted
from it," not, however, because the form is the difference
but rather because it is the principle of the difference, as Avicenna
himself says in his Metaphysicae V, cap. 6. Further, this
difference is called a simple difference because it is taken from
that which is a part of the quiddity of the thing, namely, from
the form. But since immaterial substances are simple quiddities,
in such substances the difference cannot be taken from that which
is a part of the quiddity but only from the whole quiddity, and
so in De Anima I, cap. 1, Avicenna says that substances
"have no simple difference except for those species of which
the essences are composed of matter and form."
Similarly, in immaterial things the genus is taken from the whole
essence, though not in the same way as the difference is. One
separated substance is like another with respect to their immateriality,
but they differ one from another with respect to their grade of
perfection according to how far each recedes from potentiality
and approaches pure act. And so, in such substances, the genus
is taken from that which arises in these substances insofar as
they are immaterial, as intellectuality and such things; the difference,
however, is taken from that which arises in these substances from
their grade of perfection, although these differences are unknown
to us. Nor are these differences accidental because they arise
from greater and lesser perfection, which do not diversify the
species. For, while the grade of perfection in receiving the same
form does not diversify the species (as whiter and less white
in participating in whiteness of the same type), nevertheless,
a different grade of perfection in these participated forms or
natures does diversify the species, just as nature proceeds by
grades from plants to animals through those things that are median
between plants and animals, as the Philosopher says in VIII De
Historia Animalium cap. 1 (588b4-12). Nor is it necessary
that the division of intellectual substances always be made through
two true differences, for it is impossible that this happen in
all things, as the Philosopher says in I De Partibus Animalium cap. 2 (642b5-7).
In a third way, essence is found in substances composed of matter
and form, in which existence is both received and limited because
such substances have existence from another, and again because
the nature or quiddity of such substances is received in signate
matter. And thus such substances are finite in both a superior
way and an inferior way, and among such substances, because of
the division of signate matter, there can be a multiplication
of individuals in one species. The ways in which the essence in
such substances is related to the logical intentions we have explained
above.
Chapter VI
We should now see in what way there are essences in accidents,
having said already how essences are found in all types of substances.
Now, since, as said above, the essence is that which is signified
by the definition, accidents will thus have essences in the same
way in which they have definitions. But accidents have incomplete
definitions, because they cannot be defined unless we put a subject
in their definitions, and this is because they do not have absolute
existence per se apart from a subject, but just as from the form
and the matter substantial existence results when a substance
is compounded, so too from the accident and the subject does accidental
existence result when the accident comes to the subject. Thus,
neither the substantial form nor the matter has a complete essence,
for even in the definition of the substantial form we place something
of which it is the form, and so its definition involves the addition
of something that is beyond its genus, just as with the definition
of an accidental form. Hence, the natural philosopher places the
body in the definition of the soul because he considers the soul
only insofar as it is the form of the physical body.
But this is the case only with substantial and accidental forms
because, just as the substantial form has no absolute existence
per se without that to which the form comes, so too does that
to which the form comes, namely matter, have no absolute per se
existence. Thus, from the conjunction of both there results that
existence in which the thing per se subsists, and from these two
there is made one thing per se; for, from the conjunction of these
there results a certain essence. Hence, although considered in
itself the form does not have the complete aspect of an essence,
nevertheless it is part of a complete essence. But that to which
an accident comes is in itself a complete being subsisting in
its own existence, and this existence naturally precedes the accident
that supervenes. Therefore, the supervening accident, from its
conjunction with the thing to which it comes, does not cause that
existence in which the thing subsists, the existence through which
the thing is a being per se; it causes, rather, a certain secondary
existence without which the subsisting being can be understood
to exist, as what is first can be understood without what is second.
Hence, from the accident and the subject there is made something
that is one accidentally, not essentially; and so from the conjunction
of these two there does not result an essence, as there does from
the conjunction of form and matter. And so an accident has neither
the aspect of a complete essence nor is it a part of an essence;
rather, just as an accident is a being only in a certain sense,
so too does it have an essence only in a certain sense.
But since that which is greatest and truest in a genus is the
cause of the lesser things in the genus (as fire, which is at
the extreme of heat, is the cause of heat in other hot things,
as the Philosopher says in II Metaphysicae cap. 1 (993b24-27)),
thus substance, which is first in the genus of beings and which
has essence in the truest and greatest way, is the cause of accidents,
which participate in the notion of being only secondarily and
in a certain sense. But this happens in a variety of ways. Since
the parts of substance are matter and form, certain accidents
are principally a consequence of form, and certain accidents are
principally a consequence of matter. Now, while we find some forms,
like the intellectual soul, whose existence does not depend on
matter, matter does not have existence except through form. Hence,
among those accidents that are a consequence of form, there are
some that have no communication with matter, such as understanding,
which does not take place through a corporeal organ, as the Philosopher
proves in III De Anima cap. 1 (429a18-b5). Other accidents
that are a consequence of form do have communication with matter,
and among these is sensation. But no accident a consequence of
matter is without some communication with form.
Among the accidents that are consequences of matter there is found
a certain diversity. Some accidents follow from the order the
matter has to a special form, as the masculine and the feminine
in animals, the difference between which is reduced to the matter,
as the Philosopher says in X Metaphysicae cap. 9 (1058b21-23).
Hence, the form of the animal having been removed, these accidents
do not remain except in some equivocal sense. Other accidents
follow from the order the matter has to a general form, and so
with these accidents, if the special form is removed, the accidents
still remain in the thing, as the blackness of the skin of an
Ethiopian comes from the mixture of the elements and not from
the notion of the soul, and hence the blackness remains in the
man after death.
Since everything is individuated by matter and is placed in its
genus or species through its form, the accidents that follow from
the matter are accidents of the individual, and by these accidents
individuals of the same species differ one from another. But the
accidents that follow from the form are properly passions of the
genus or species, and so they are found in all things participating
in the nature of the genus or species, as risibility in man follows
from the form, for laughter comes from a certain kind of understanding
in the soul of man.
We should also note that some accidents are caused by the essential
principles of a thing according to its perfect act, as heat in
fire, which is always hot, while other accidents are the result
of an aptitude in the substance, and in such cases the complete
accident arises from an exterior agent, as transparency in air,
which is completed through an exterior luminescent body. In such
things, the aptitude is an inseparable accident, but the complement,
which comes from some principle that is beyond the essence of
the thing, or that does not enter into the constitution of the
thing, is separable, as the ability to be moved, and so on.
We should further note that in accidents, the genus, difference,
and species are taken in a way different from that in substances.
For in substances, from the substantial form and the matter there
is made something one per se, a certain single nature resulting
from the conjunction of these two, and this nature is properly
placed in the predicament of substance. Hence, in substances,
the concrete terms that signify the composite are properly said
to be in the genus, in the manner of the species or the genus,
as, for example, man or animal. But in this way neither the form
nor the matter is in a predicament except by means of reduction,
as when we say that the principles of a thing are in its genus.
However, from the accident and the subject there does not result
something that is one per se, and thus from the conjunction of
these two there does not result a nature to which the intention
of genus or species might be attributed. Therefore, the accidental
terms taken concretely, like white or musical, cannot be placed
in a predicament except by means of reduction; but they can be
placed in a predicament when they are signified abstractly, as
whiteness and music. And because accidents are not composed of
matter and form, in accidents the genus cannot be taken from the
matter, the difference from the form, as is the case with composite
substances; rather, the first genus is taken from their very mode
of existing, as being is said in different ways according to what
is prior and what is posterior in the ten genera of predicaments,
and thus we call the measure of a substance quantity, the disposition
of a substance quality, and so on for the others, as the Philosopher
says in IX Metaphysicae cap. 1 (1045b27-32).
The differences in accidents are taken from the diversity of principles
by which they are caused. Since passions are properly caused by
the proper principles of the subject, the subject is placed in
the definition of the passion in place of the difference if the
passion is being defined in the abstract and properly in its genus,
as when we say that having a snubnose is the upward curvature
of the nose. But it would be the converse if the definition of
the passion were taken according to its concrete sense; in this
way, the subject is placed in the definition as a genus, for then
the passion is defined in the mode of composite substances in
which the notion of the genus is taken from the matter, as when
we say that a snubnose is an upwardly curving nose. The case is
similar when one accident is the principle of another, as the
principle of relation is action and passion and quantity, and
thus by reference to these the Philosopher divides relation in
V Metaphysicae cap. 15 (1020b26-32). But because the proper
principles of accidents are not always manifest, we sometimes
take the differences of accidents from their effects, as we do
with the concentrative and the diffusive, which are called the
differences of color and which are caused by the abundance or
the paucity of light, which cause the different species of color.
We have thus made clear how essence is found in substances and
in accidents, and how in composite substances and in simple ones,
and in what way the universal intentions of logic are found in
all of these, except for the first being, which is the extreme
of simplicity and to which, because of its simplicity, the notions
of genus, species, and thus definition do not apply; and having
said this we may make an proper end to this discourse. Amen.
NOTES:
[1] This
translation follows the Leonine Edition of Aquinas' works, vol.
43 Sancti Thomae De Aquino Opera Omnia 368-381 (Rome 1976).
[2] All persons are licensed
to reproduce this translation and the footnotes hereto for personal
or educational purposes, provided that the notice of copyright
set forth above and this notice are included in their respective
entireties in all copies. This license includes reproduction by
a commercial entity engaged in the business of providing copying
services if such reproduction is made pursuant to an agreement
the other party to which would be licensed under the preceding
sentence to reproduce this translation for personal or educational
purposes.
[3] Although
quoted by various thirteenth century authors, this statement does
not appear in the text of De Persona et Duabus Naturis as
we have it.
[4] Aquinas
knew this book as Book XI.
This text is part of the Internet Medieval Source Book.
The Sourcebook is a collection of public domain and copy-permitted
texts related to medieval and Byzantine history.
Unless otherwise indicated the specific electronic form of the
document is copyright. Permission is granted for electronic copying,
distribution in print form for educational purposes and personal
use. If you do reduplicate the document, indicate the source.
No permission is granted for commercial use.
Paul Halsall October 1997
halsall@murray.fordham.edu
The Internet Medieval Sourcebook is part of the Internet History Sourcebooks Project. The Internet History Sourcebooks Project is located at the History Department of Fordham University, New York. The Internet
Medieval Sourcebook, and other medieval components of the project, are located at
the Fordham University Center
for Medieval Studies.The IHSP recognizes the contribution of Fordham University, the
Fordham University History Department, and the Fordham Center for Medieval Studies in
providing web space and server support for the project. The IHSP is a project independent of Fordham University.
Although the IHSP seeks to follow all applicable copyright law, Fordham University is not
the institutional owner, and is not liable as the result of any legal action.
© Site Concept and Design: Paul Halsall created 26 Jan 1996: latest revision 24 October 2024 [CV]
|