Translated by E. M. Edghill
Part 1 - Homonyms, Synonyms, and
Things are said to be named 'equivocally'
when, though they have a common name, the definition
corresponding with the name differs for each. Thus, a real man
and a figure in a picture can both lay claim to the name
'animal'; yet these are equivocally so named, for, though they
have a common name, the definition corresponding with the name
differs for each. For should any one define in what sense each is
an animal, his definition in the one case will be appropriate to
that case only.
On the other hand, things are said to be
named 'univocally' which have both the name and the definition
answering to the name in common. A man and an ox are both
'animal', and these are univocally so named, inasmuch as not only
the name, but also the definition, is the same in both cases: for
if a man should state in what sense each is an animal, the
statement in the one case would be identical with that in the
Things are said to be named 'derivatively',
which derive their name from some other name, but differ from it
in termination. Thus the grammarian derives his name from the
word 'grammar', and the courageous man from the word 'courage'.
Part 2 - Simple and Composite Expressions
Forms of speech are either simple or
composite. Examples of the latter are such expressions as 'the
man runs', 'the man wins'; of the former 'man', 'ox', 'runs',
Of things themselves some are predicable of
a subject, and are never present in a subject. Thus 'man' is
predicable of the individual man, and is never present in a
By being 'present in a subject' I do not
mean present as parts are present in a whole, but being incapable
of existence apart from the said subject.
Some things, again, are present in a
subject, but are never predicable of a subject. For instance, a
certain point of grammatical knowledge is present in the mind,
but is not predicable of any subject; or again, a certain
whiteness may be present in the body (for colour requires a
material basis), yet it is never predicable of anything.
Other things, again, are both predicable of
a subject and present in a subject. Thus while knowledge is
present in the human mind, it is predicable of grammar.
There is, lastly, a class of things which
are neither present in a subject nor predicable of a subject,
such as the individual man or the individual horse. But, to speak
more generally, that which is individual and has the character of
a unit is never predicable of a subject. Yet in some cases there
is nothing to prevent such being present in a subject. Thus a
certain point of grammatical knowledge is present in a subject.
Part 3 - Concerning Predicates
When one thing is predicated of another,
all that which is predicable of the predicate will be predicable
also of the subject. Thus, 'man' is predicated of the individual
man; but 'animal' is predicated of 'man'; it will, therefore, be
predicable of the individual man also: for the individual man is
both 'man' and 'animal'.
If genera are different and co-ordinate,
their differentiae are themselves different in kind. Take as an
instance the genus 'animal' and the genus 'knowledge'. 'With
feet', 'two-footed', 'winged', 'aquatic', are differentiae of
'animal'; the species of knowledge are not distinguished by the
same differentiae. One species of knowledge does not differ from
another in being 'two-footed'.
But where one genus is subordinate to
another, there is nothing to prevent their having the same
differentiae: for the greater class is predicated of the lesser,
so that all the differentiae of the predicate will be
differentiae also of the subject.
Part 4 - The Eight Categories of the Objects of
Expressions which are in no way composite
signify substance, quantity, quality, relation, place, time,
position, state, action, or affection. To sketch my meaning
roughly, examples of substance are 'man' or 'the horse', of
quantity, such terms as 'two cubits long' or 'three cubits long',
of quality, such attributes as 'white', 'grammatical'. 'Double',
'half', 'greater', fall under the category of relation; 'in a the
market place', 'in the Lyceum', under that of place; 'yesterday',
'last year', under that of time. 'Lying', 'sitting', are terms
indicating position, 'shod', 'armed', state; 'to lance', 'to
cauterize', action; 'to be lanced', 'to be cauterized', affection.
No one of these terms, in and by itself,
involves an affirmation; it is by the combination of such terms
that positive or negative statements arise. For every assertion
must, as is admitted, be either true or false, whereas
expressions which are not in any way composite such as 'man',
'white', 'runs', 'wins', cannot be either true or false.
Part 5 - Substance
Substance, in the truest and primary and
most definite sense of the word, is that which is neither
predicable of a subject nor present in a subject; for instance,
the individual man or horse. But in a secondary sense those
things are called substances within which, as species, the
primary substances are included; also those which, as genera,
include the species. For instance, the individual man is included
in the species 'man', and the genus to which the species belongs
is 'animal'; these, therefore-that is to say, the species 'man'
and the genus 'animal,-are termed secondary substances.
It is plain from what has been said that
both the name and the definition of the predicate must be
predicable of the subject. For instance, 'man' is predicted of
the individual man. Now in this case the name of the species man'
is applied to the individual, for we use the term 'man' in
describing the individual; and the definition of 'man' will also
be predicated of the individual man, for the individual man is
both man and animal. Thus, both the name and the definition of
the species are predicable of the individual.
With regard, on the other hand, to those
things which are present in a subject, it is generally the case
that neither their name nor their definition is predicable of
that in which they are present. Though, however, the definition
is never predicable, there is nothing in certain cases to prevent
the name being used. For instance, 'white' being present in a
body is predicated of that in which it is present, for a body is
called white: the definition, however, of the colour white' is
never predicable of the body.
Everything except primary substances is
either predicable of a primary substance or present in a primary
substance. This becomes evident by reference to particular
instances which occur. 'Animal' is predicated of the species
'man', therefore of the individual man, for if there were no
individual man of whom it could be predicated, it could not be
predicated of the species 'man' at all. Again, colour is present
in body, therefore in individual bodies, for if there were no
individual body in which it was present, it could not be present
in body at all. Thus everything except primary substances is
either predicated of primary substances, or is present in them,
and if these last did not exist, it would be impossible for
anything else to exist.
Of secondary substances, the species is
more truly substance than the genus, being more nearly related to
primary substance. For if any one should render an account of
what a primary substance is, he would render a more instructive
account, and one more proper to the subject, by stating the
species than by stating the genus. Thus, he would give a more
instructive account of an individual man by stating that he was
man than by stating that he was animal, for the former
description is peculiar to the individual in a greater degree,
while the latter is too general. Again, the man who gives an
account of the nature of an individual tree will give a more
instructive account by mentioning the species 'tree' than by
mentioning the genus 'plant'.
Moreover, primary substances are most
properly called substances in virtue of the fact that they are
the entities which underlie every. else, and that everything else
is either predicated of them or present in them. Now the same
relation which subsists between primary substance and everything
else subsists also between the species and the genus: for the
species is to the genus as subject is to predicate, since the
genus is predicated of the species, whereas the species cannot be
predicated of the genus. Thus we have a second ground for
asserting that the species is more truly substance than the genus.
Of species themselves, except in the case
of such as are genera, no one is more truly substance than
another. We should not give a more appropriate account of the
individual man by stating the species to which he belonged, than
we should of an individual horse by adopting the same method of
definition. In the same way, of primary substances, no one is
more truly substance than another; an individual man is not more
truly substance than an individual ox.
It is, then, with good reason that of all
that remains, when we exclude primary substances, we concede to
species and genera alone the name 'secondary substance', for
these alone of all the predicates convey a knowledge of primary
substance. For it is by stating the species or the genus that we
appropriately define any individual man; and we shall make our
definition more exact by stating the former than by stating the
latter. All other things that we state, such as that he is white,
that he runs, and so on, are irrelevant to the definition. Thus
it is just that these alone, apart from primary substances,
should be called substances.
Further, primary substances are most
properly so called, because they underlie and are the subjects of
everything else. Now the same relation that subsists between
primary substance and everything else subsists also between the
species and the genus to which the primary substance belongs, on
the one hand, and every attribute which is not included within
these, on the other. For these are the subjects of all such. If
we call an individual man 'skilled in grammar', the predicate is
applicable also to the species and to the genus to which he
belongs. This law holds good in all cases.
It is a common characteristic of all sub.
stance that it is never present in a subject. For primary
substance is neither present in a subject nor predicated of a
subject; while, with regard to secondary substances, it is clear
from the following arguments (apart from others) that they are
not present in a subject. For 'man' is predicated of the
individual man, but is not present in any subject: for manhood is
not present in the individual man. In the same way, 'animal' is
also predicated of the individual man, but is not present in him.
Again, when a thing is present in a subject, though the name may
quite well be applied to that in which it is present, the
definition cannot be applied. Yet of secondary substances, not
only the name, but also the definition, applies to the subject:
we should use both the definition of the species and that of the
genus with reference to the individual man. Thus substance cannot
be present in a subject.
Yet this is not peculiar to substance, for
it is also the case that differentiae cannot be present in
subjects. The characteristics 'terrestrial' and 'two-footed' are
predicated of the species 'man', but not present in it. For they
are not in man. Moreover, the definition of the differentia may
be predicated of that of which the differentia itself is
predicated. For instance, if the characteristic 'terrestrial' is
predicated of the species 'man', the definition also of that
characteristic may be used to form the predicate of the species
'man': for 'man' is terrestrial.
The fact that the parts of substances
appear to be present in the whole, as in a subject, should not
make us apprehensive lest we should have to admit that such parts
are not substances: for in explaining the phrase 'being present
in a subject', we stated' that we meant 'otherwise than as parts
in a whole'.
It is the mark of substances and of
differentiae that, in all propositions of which they form the
predicate, they are predicated univocally. For all such
propositions have for their subject either the individual or the
species. It is true that, inasmuch as primary substance is not
predicable of anything, it can never form the predicate of any
proposition. But of secondary substances, the species is
predicated of the individual, the genus both of the species and
of the individual. Similarly the differentiae are predicated of
the species and of the individuals. Moreover, the definition of
the species and that of the genus are applicable to the primary
substance, and that of the genus to the species. For all that is
predicated of the predicate will be predicated also of the
subject. Similarly, the definition of the differentiae will be
applicable to the species and to the individuals. But it was
stated above that the word 'univocal' was applied to those things
which had both name and definition in common. It is, therefore,
established that in every proposition, of which either substance
or a differentia forms the predicate, these are predicated
All substance appears to signify that which
is individual. In the case of primary substance this is
indisputably true, for the thing is a unit. In the case of
secondary substances, when we speak, for instance, of 'man' or
'animal', our form of speech gives the impression that we are
here also indicating that which is individual, but the impression
is not strictly true; for a secondary substance is not an
individual, but a class with a certain qualification; for it is
not one and single as a primary substance is; the words 'man',
'animal', are predicable of more than one subject.
Yet species and genus do not merely
indicate quality, like the term 'white'; 'white' indicates
quality and nothing further, but species and genus determine the
quality with reference to a substance: they signify substance
qualitatively differentiated. The determinate qualification
covers a larger field in the case of the genus that in that of
the species: he who uses the word 'animal' is herein using a word
of wider extension than he who uses the word 'man'.
Another mark of substance is that it has no
contrary. What could be the contrary of any primary substance,
such as the individual man or animal? It has none. Nor can the
species or the genus have a contrary. Yet this characteristic is
not peculiar to substance, but is true of many other things, such
as quantity. There is nothing that forms the contrary of 'two
cubits long' or of 'three cubits long', or of 'ten', or of any
such term. A man may contend that 'much' is the contrary of
'little', or 'great' of 'small', but of definite quantitative
terms no contrary exists.
Substance, again, does not appear to admit
of variation of degree. I do not mean by this that one substance
cannot be more or less truly substance than another, for it has
already been stated' that this is the case; but that no single
substance admits of varying degrees within itself. For instance,
one particular substance, 'man', cannot be more or less man
either than himself at some other time or than some other man.
One man cannot be more man than another, as that which is white
may be more or less white than some other white object, or as
that which is beautiful may be more or less beautiful than some
other beautiful object. The same quality, moreover, is said to
subsist in a thing in varying degrees at different times. A body,
being white, is said to be whiter at one time than it was before,
or, being warm, is said to be warmer or less warm than at some
other time. But substance is not said to be more or less that
which it is: a man is not more truly a man at one time than he
was before, nor is anything, if it is substance, more or less
what it is. Substance, then, does not admit of variation of
The most distinctive mark of substance
appears to be that, while remaining numerically one and the same,
it is capable of admitting contrary qualities. From among things
other than substance, we should find ourselves unable to bring
forward any which possessed this mark. Thus, one and the same
colour cannot be white and black. Nor can the same one action be
good and bad: this law holds good with everything that is not
substance. But one and the selfsame substance, while retaining
its identity, is yet capable of admitting contrary qualities. The
same individual person is at one time white, at another black, at
one time warm, at another cold, at one time good, at another bad.
This capacity is found nowhere else, though it might be
maintained that a statement or opinion was an exception to the
rule. The same statement, it is agreed, can be both true and
false. For if the statement 'he is sitting' is true, yet, when
the person in question has risen, the same statement will be
false. The same applies to opinions. For if any one thinks truly
that a person is sitting, yet, when that person has risen, this
same opinion, if still held, will be false. Yet although this
exception may be allowed, there is, nevertheless, a difference in
the manner in which the thing takes place. It is by themselves
changing that substances admit contrary qualities. It is thus
that that which was hot becomes cold, for it has entered into a
different state. Similarly that which was white becomes black,
and that which was bad good, by a process of change; and in the
same way in all other cases it is by changing that substances are
capable of admitting contrary qualities. But statements and
opinions themselves remain unaltered in all respects: it is by
the alteration in the facts of the case that the contrary quality
comes to be theirs. The statement 'he is sitting' remains
unaltered, but it is at one time true, at another false,
according to circumstances. What has been said of statements
applies also to opinions. Thus, in respect of the manner in which
the thing takes place, it is the peculiar mark of substance that
it should be capable of admitting contrary qualities; for it is
by itself changing that it does so.
If, then, a man should make this exception
and contend that statements and opinions are capable of admitting
contrary qualities, his contention is unsound. For statements and
opinions are said to have this capacity, not because they
themselves undergo modification, but because this modification
occurs in the case of something else. The truth or falsity of a
statement depends on facts, and not on any power on the part of
the statement itself of admitting contrary qualities. In short,
there is nothing which can alter the nature of statements and
opinions. As, then, no change takes place in themselves, these
cannot be said to be capable of admitting contrary qualities.
But it is by reason of the modification
which takes place within the substance itself that a substance is
said to be capable of admitting contrary qualities; for a
substance admits within itself either disease or health,
whiteness or blackness. It is in this sense that it is said to be
capable of admitting contrary qualities.
To sum up, it is a distinctive mark of
substance, that, while remaining numerically one and the same, it
is capable of admitting contrary qualities, the modification
taking place through a change in the substance itself.
Let these remarks suffice on the subject of
Part 6 - Quantity
Quantity is either discrete or continuous.
Moreover, some quantities are such that each part of the whole
has a relative position to the other parts: others have within
them no such relation of part to part.
Instances of discrete quantities are number
and speech; of continuous, lines, surfaces, solids, and, besides
these, time and place.
In the case of the parts of a number, there
is no common boundary at which they join. For example: two fives
make ten, but the two fives have no common boundary, but are
separate; the parts three and seven also do not join at any
boundary. Nor, to generalize, would it ever be possible in the
case of number that there should be a common boundary among the
parts; they are always separate. Number, therefore, is a discrete
The same is true of speech. That speech is
a quantity is evident: for it is measured in long and short
syllables. I mean here that speech which is vocal. Moreover, it
is a discrete quantity for its parts have no common boundary.
There is no common boundary at which the syllables join, but each
is separate and distinct from the rest.
A line, on the other hand, is a continuous
quantity, for it is possible to find a common boundary at which
its parts join. In the case of the line, this common boundary is
the point; in the case of the plane, it is the line: for the
parts of the plane have also a common boundary. Similarly you can
find a common boundary in the case of the parts of a solid,
namely either a line or a plane.
Space and time also belong to this class of
quantities. Time, past, present, and future, forms a continuous
whole. Space, likewise, is a continuous quantity; for the parts
of a solid occupy a certain space, and these have a common
boundary; it follows that the parts of space also, which are
occupied by the parts of the solid, have the same common boundary
as the parts of the solid. Thus, not only time, but space also,
is a continuous quantity, for its parts have a common boundary.
Quantities consist either of parts which
bear a relative position each to each, or of parts which do not.
The parts of a line bear a relative position to each other, for
each lies somewhere, and it would be possible to distinguish
each, and to state the position of each on the plane and to
explain to what sort of part among the rest each was contiguous.
Similarly the parts of a plane have position, for it could
similarly be stated what was the position of each and what sort
of parts were contiguous. The same is true with regard to the
solid and to space. But it would be impossible to show that the
arts of a number had a relative position each to each, or a
particular position, or to state what parts were contiguous. Nor
could this be done in the case of time, for none of the parts of
time has an abiding existence, and that which does not abide can
hardly have position. It would be better to say that such parts
had a relative order, in virtue of one being prior to another.
Similarly with number: in counting, 'one' is prior to 'two', and
'two' to 'three', and thus the parts of number may be said to
possess a relative order, though it would be impossible to
discover any distinct position for each. This holds good also in
the case of speech. None of its parts has an abiding existence:
when once a syllable is pronounced, it is not possible to retain
it, so that, naturally, as the parts do not abide, they cannot
have position. Thus, some quantities consist of parts which have
position, and some of those which have not.
Strictly speaking, only the things which I
have mentioned belong to the category of quantity: everything
else that is called quantitative is a quantity in a secondary
sense. It is because we have in mind some one of these
quantities, properly so called, that we apply quantitative terms
to other things. We speak of what is white as large, because the
surface over which the white extends is large; we speak of an
action or a process as lengthy, because the time covered is long;
these things cannot in their own right claim the quantitative
epithet. For instance, should any one explain how long an action
was, his statement would be made in terms of the time taken, to
the effect that it lasted a year, or something of that sort. In
the same way, he would explain the size of a white object in
terms of surface, for he would state the area which it covered.
Thus the things already mentioned, and these alone, are in their
intrinsic nature quantities; nothing else can claim the name in
its own right, but, if at all, only in a secondary sense.
Quantities have no contraries. In the case
of definite quantities this is obvious; thus, there is nothing
that is the contrary of 'two cubits long' or of 'three cubits
long', or of a surface, or of any such quantities. A man might,
indeed, argue that 'much' was the contrary of 'little', and
'great' of 'small'. But these are not quantitative, but relative;
things are not great or small absolutely, they are so called
rather as the result of an act of comparison. For instance, a
mountain is called small, a grain large, in virtue of the fact
that the latter is greater than others of its kind, the former
less. Thus there is a reference here to an external standard, for
if the terms 'great' and 'small' were used absolutely, a mountain
would never be called small or a grain large. Again, we say that
there are many people in a village, and few in Athens, although
those in the city are many times as numerous as those in the
village: or we say that a house has many in it, and a theatre
few, though those in the theatre far outnumber those in the house.
The terms 'two cubits long, "three cubits long,' and so on
indicate quantity, the terms 'great' and 'small' indicate
relation, for they have reference to an external standard. It is,
therefore, plain that these are to be classed as relative.
Again, whether we define them as
quantitative or not, they have no contraries: for how can there
be a contrary of an attribute which is not to be apprehended in
or by itself, but only by reference to something external? Again,
if 'great' and 'small' are contraries, it will come about that
the same subject can admit contrary qualities at one and the same
time, and that things will themselves be contrary to themselves.
For it happens at times that the same thing is both small and
great. For the same thing may be small in comparison with one
thing, and great in comparison with another, so that the same
thing comes to be both small and great at one and the same time,
and is of such a nature as to admit contrary qualities at one and
the same moment. Yet it was agreed, when substance was being
discussed, that nothing admits contrary qualities at one and the
same moment. For though substance is capable of admitting
contrary qualities, yet no one is at the same time both sick and
healthy, nothing is at the same time both white and black. Nor is
there anything which is qualified in contrary ways at one and the
Moreover, if these were contraries, they
would themselves be contrary to themselves. For if 'great' is the
contrary of 'small', and the same thing is both great and small
at the same time, then 'small' or 'great' is the contrary of
itself. But this is impossible. The term 'great', therefore, is
not the contrary of the term 'small', nor 'much' of 'little'. And
even though a man should call these terms not relative but
quantitative, they would not have contraries.
It is in the case of space that quantity
most plausibly appears to admit of a contrary. For men define the
term 'above' as the contrary of 'below', when it is the region at
the centre they mean by 'below'; and this is so, because nothing
is farther from the extremities of the universe than the region
at the centre. Indeed, it seems that in defining contraries of
every kind men have recourse to a spatial metaphor, for they say
that those things are contraries which, within the same class,
are separated by the greatest possible distance.
Quantity does not, it appears, admit of
variation of degree. One thing cannot be two cubits long in a
greater degree than another. Similarly with regard to number:
what is 'three' is not more truly three than what is 'five' is
five; nor is one set of three more truly three than another set.
Again, one period of time is not said to be more truly time than
another. Nor is there any other kind of quantity, of all that
have been mentioned, with regard to which variation of degree can
be predicated. The category of quantity, therefore, does not
admit of variation of degree.
The most distinctive mark of quantity is
that equality and inequality are predicated of it. Each of the
aforesaid quantities is said to be equal or unequal. For
instance, one solid is said to be equal or unequal to another;
number, too, and time can have these terms applied to them,
indeed can all those kinds of quantity that have been mentioned.
That which is not a quantity can by no
means, it would seem, be termed equal or unequal to anything else.
One particular disposition or one particular quality, such as
whiteness, is by no means compared with another in terms of
equality and inequality but rather in terms of similarity. Thus
it is the distinctive mark of quantity that it can be called
equal and unequal.
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