PORPHYRY, INTRODUCTION (ISAGOGE)

Translated by Thomas Taylor (1758-1835), adapted by William C. Michael (2022)

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Porphyry, Introduction. Chapter 1

1. Since it is necessary, both to the doctrine of the Categories of Aristotle, and to the formation of definitions, and in short, to those things which pertain to division and demonstration, to know what Genus and Difference, Species, Peculiarity, and Accident are; and since also the theory of these is useful:

2. In a summary way, I will briefly endeavour to discuss for you, in the form, as it were, of an Introduction, what has been delivered on this subject by the ancients, abstaining from more profound investigations, but appropriately directing my attention to such as are more simple.

3. My meaning is, that I shall omit to speak about Genera and Species, whether they have a subsistence in the nature of things or have an existence alone in the mere conceptions of the soul; and if they have a subsistence in the nature of things whether they are bodies or incorporeal, and whether they are separate from sensibles, or in sensibles, and about these have their subsistence.  For a discussion of this kind is most profound, and requires another, and a greater investigation.

4. In what manner, however, the ancients, and especially the Peripatetics discussed these, and the other proposed objects of enquiry, in a more logical manner, I will now endeavour to show you.

Porphyry, Introduction. Chapter 2

1. It seems indeed, that neither Genus nor Species is simply denominated.

2. For a collection of certain things, subsisting in a certain respect with reference to one thing, and to each other, is called Genus; according to which signification the Genus of the Heraclidae is denominated from the habitude from one thing, I mean from Hercules, and the multitude of those who derive in a certain respect alliance from him; being Thus, denominated, according to abscission from other Genera.

3. After another manner also the principle of the Generation of everyone is again denominated Genus, whether from the Generator, or from the place in which someone is born. Hence, we say that Orestes derived his Genus from Tantalus, but Hyllus from Hercules. And, again we say, that Pindar was by Genus a Theban; but Plato an Athenian: for country is a certain principle of the Generation of everyone, in the same manner as a father.

4. This signification however appears to be one that may be easily adopted.  For those are called Heraclidae who derive their origin from the Genus of Hercules; and Cecropidae who derive it from Cecrops; and also those who have an affinity to these.

5. And the first Genus is denominated that whence, the principle of the Generation of any one is derived; but afterwards, the multitude of those who originate from one principle, as for instance, from Hercules; which Genus defining and separating from others, we call the whole collected multitude, the Genus of the Heraclidae.

6. Again, after another manner, Genus is denominated that, to which Species is subjected, being Thus, called perhaps according to the similitude of these. For a Genus of this kind is a certain principle of the things which are under it, and appears also to comprehend all the multitude which is under it.

7. Since therefore Genus is denominated in a threefold manner, the third is that which is considered by philosophers.

8. Which also describing they explain, when they say that Genus is that which is predicated of many things, differing in Species, in answer to the question what a thing is; as for instance, animal.

9. For of things which are predicated, some are predicated of one thing only, as individuals, as for instance Socrates, and this man, and that thing; but others are predicated of many things, as Genera and Species, Differences, peculiarities and Accidents, which are predicated of many things in common, and are not peculiar to any individual thing.  But Genus is indeed, such as animal; and Species, such as man; Difference is such as rational; Peculiarity, such as risible; and Accident, such as the white, the black, and to sit.

10. Genera therefore differ from things which are predicated of one thing only in this, that they are predicated of many things.

11. But Genera differ from those which are predicated of many things, and in the first place from Species, because though Species are predicated of many things, yet not of things differing in Species, but in number. Thus, man, being a Species, is predicated of Socrates and Plato, who do not differ from each other in Species, but in number. But animal being a Genus, is predicated of man and ox, and horse, which differ also in Species from each other, and not in number only.

12. Again, Genus differs from Peculiarity in this, that Peculiarity is predicated of one Species alone, of which it is the Peculiarity, and of the individuals under that Species. Thus, risibility is predicated of man alone, and of the individuals of the human Species; but Genus is not predicated of one Species, but of many things, and which differ in Species.

13. Farther still, Genus differs from Difference, and from Accidents which are common, because though Differences and Accidents which are common, are predicated of many things, and which differ in Species, yet they are not predicated in answer to the question, “What is this?”, but in answer to the question, “What kind of a thing is this?”. For certain persons enquiring what that is, of which these things are predicated, we answer, that it is Genus; but we do not answer that it is Differences and Accidents; since these are not predicated of a subject in answer to the question “What is this?”, but rather in answer to the question “What kind of a thing is this?”.  For when anyone asks what kind of a thing man is, we say that he is a rational being; and in answer to the question “What kind of thing is a crow?”, we say that “A crow is black.”.  Rational however is Difference but black is Accident, but when we ask “What is man?”, we answer “Man is an animal.”; and animal is the Genus of man.

14. Hence, because Genus is predicated of many things, it is separated from individuals which are predicated of one thing only.

15. But because it is predicated of things differing in Species, it is distinguished from things which are predicated as Species, or as peculiarities.

16. And because it is predicated in answer to the question, “What is this?”, it is separated from Differences, and from common Accidents, each of which is predicated of those things of which it is predicated, not in answer to the question “What is this?”, but in answer to the question, “What kind of a thing is this?”, or “In what manner does this subsist?”.

17. The above-mentioned description therefore of the conception of Genus, contains nothing superfluous, nothing deficient.

18. Species, however, is predicated indeed of every form, according to which signification it is said, 

Form is first worthy of imperial sway. 

19. That also is called Species, which is placed under the Genus already explained, according to which signification we are accustomed to say that man is a Species of animal, animal being a Genus; that the white is a Species of colour; and that triangle is a Species of figure.

20. If, however, in explaining Genus we make mention of Species, and say that Genus is that which is predicated of many things differing in Species, in answer to the question what a thing is, and that Species is that which is under the aforesaid Genus;  it is requisite to know that since Genus is the Genus of some things and Species the Species of something, each of each, it is necessary to use both the definitions of both.

21. They unfold therefore the meaning of Species as follows:  Species is that which is arranged under Genus, and of which Genus is predicated in answer to the question “What a thing is?”.  They also explain it thus: Species is that which is predicated of many things differing in number, in answer to the question “What is this?”. 

22. This explanation, however, pertains to the most Special Species, and which is Species only, but no longer Genus also; but the other explanations will pertain to Species which are not most Special. 

23. What we have said however will be evident after this manner:  In each category, there are certain things which are most General, and again others which are most Special; and between things the most General and the most Special there are others, which are called both Genera and Species. But the Genus which is most General, is that above which there will no longer be another superior Genus; and the most Special Species is that after which there will not be another inferior Species. Between the most General Genus, and the most Special Species also, there are other things which are both Genera and Species, when referred however to different things.

24. But what has been said will become evident in one category. Essence, is indeed itself a Genus. Under this is body. And under body is animated body; under which is animal. Under animal is rational animal; under which is man. And under man are Socrates and Plato, and the individuals of the human Species.  Of these however Essence is the “most General”, and that which is alone Genus; and man is “most Special”, and that which is alone Species. But body is a Species of Essence, and the Genus of animated body. Animated body also is a Species of body, but the Genus of animal. Again, animal is a Species indeed of animated body, but the Genus of rational animal. And rational animal, is a Species indeed of animal, but the Genus of man. And man is a Species indeed of rational animal, but is no longer the Genus also of particular men, but is Species alone. Every thing also prior to individuals which is proximately predicated of them, will be Species only, and no longer Genus also. Hence, as Essence which is in the highest place is most General, because there is no Genus prior to it; Thus, also man being a Species, after which there is no other Species, nor any thing which is capable of being divided into Species, but individuals, (for Socrates, Plato, and Alcibiades, and this particular white thing, are individuals) will be Species alone, and the last Species, and as we have said, the most Special Species. But the media will be the Species of the things prior to them; and the Genera of things posterior to them.

25. Hence, these have two habitudes, one to things prior to them, according to which they are said to- be the Species of them, but the other, to things posterior to them, according to which they are said to be the Genera of them.

26. But the extremes have one habitude. For that which is most General, has indeed a habitude as to the things which are under it, since it is the highest Genus of all things; but has no longer a habitude as to things prior to it, being supreme, and the first principle, and, as we have said, that above which there will not be another superior Genus.

27. The most Special Species also has one habitude, as towards things prior to it, of which it is the Species; yet it has not a different habitude, as towards things posterior to it; but it is said to be the Species of individuals, as comprehending them, and again, the Species of things prior to it, as being comprehended by them.

28. The most General Genus therefore is defined to be that which being Genus is not Species. And again, it is that above which there will not be another superior Genus.

29. But the most Special Species, is defined to be that which being Species is not Genus; and that which being Species we cannot divide into Species. Farther still, it is that also which is predicated of many things differing in number, in answer to the question, “What is this?”.

30. But the media of the extremes, are called subaltern Species and Genera, and each of them is admitted to be Genus and Species, with reference however to different things. For the things prior to the most Special Species, in an ascent as far as to the most General Genus, are called subaltern Genera and Species.

31. Thus, Agamemnon is Atrides, Pelopides, Tantalides, and in the last place, of Jupiter.

32. In genealogies however, they refer, for the most part, to one principle, for instance to Jupiter; but in Genera and Species this is not the case; for being is not the common Genus of all things, nor, as Aristotle says, are all things homogenous, according to one supreme Genus. But the first ten Genera are arranged, as in the Categories, as the first ten principles. And though some one should call all things beings, yet, says he, he will call them so homonymously, and not synonymously. For if being were the common Genus of all things, all things would be synonymously denominated beings. But the first principles being ten, the communion is in the name only, and not also in the definition pertaining to the name. The most General Genera therefore are ten.

33. But the most Special Species are indeed contained in a certain number, yet not in an infinite number.

34. Individuals however, which are after the most Special Species are infinite.

35. Hence, when we have descended as far as to the most Special Species from the most General Genera, Plato orders us to rest; but advises us to descend through those things which are in the middle, dividing by specific Differences. But infinites, says he, are to be dismissed; for of these there cannot be any science.

36. In descending therefore to the most Special Species, it is necessary by dividing to proceed through multitude; but in ascending to the most General Genera, it is necessary to collect multitude into one. For Species is collective of the many into one nature, and Genus possesses this power in a still greater degree.  On the contrary, things which subsist according to a part, and particulars, always divide the one into multitude. For by the participation of Species, the multitude of men is one man; but in things which subsist according to a part, and in particulars, that which is one and common to many is contained. For that which is particular has always a divisive power; but that which is common has the power of collecting and uniting.

37. With respect to Genus and Species therefore, having explained what each of them is, and since Genus is one thing, but Species many things, (for the division of Genus is always into many Species) Genus indeed is always predicated of Species, and all the superiors of all the inferiors; but Species is neither predicated of the Genus proximate to it, nor of the superior Genera; for neither does it reciprocate. For it is necessary, either that things equal should be predicated of things equal, as the ability of neighing is predicated of a horse; or that greater things should be predicated of lesser, as animal of man; but lesser can no longer be predicated of greater things. For you can no longer say that animal is man, as you can say that man is an animal. But of those things of which. Species is predicated, of those, the Genus of Species are also necessarily predicate the Genus of Genus, as far as to the most General Genus. For, if it is true to say that Socrates is a man, but man is an animal, and an animal is Essence or substance: it is also true to say that Socrates is an animal and an Essence. For since superiors are always predicated of inferiors, Species indeed is predicated of an individual; but Genus is predicated both of Species and an individual; and the most General Genus is predicated of Genus, or Genera; if the media and subalterns are many, and also of Species, and an individual. For the most General Genus is predicated of all the Genera, Species, and individuals contained under it; but the Genus which is prior to the most Special Species is predicated of all the most Special. Species and individuals. And that which is Species alone is predicated of all the individuals of that Species; but an individual is predicated of one particular thing alone.

38. An individual, however, is such as Socrates, this white substance, and this man who approaches, viz. the son of Sophroniscus, if Socrates is the son of Sophroniscus. But things of this kind are called individuals, because each of them consists of peculiarities, of which the collection can never belong to any other thing. For the same peculiarities as those of Socrates, cannot subsist in any other person. The same peculiarities however of man, I mean of man considered as common, can be inherent in many, or rather in all particular men, so far as they are men.

39. Hence, the individual is contained by Species, but Species by Genus. For Genus is a certain whole; but the individual is a part; and Species is both whole and part. It is a part indeed of something else, but not a whole of any thing else, but subsists in other things; for the whole is in its parts.

40. Concerning Genus and Species therefore, we have shown what they are, and also what that which is most General, and that which is most Special are, what things are both Genera and Species, what are individuals, and in how many ways Genus and Species are assumed.

Porphyry, Introduction. Chapter 3

1. Difference, however, is predicated in common, peculiarly, and most peculiarly. 

2. For one thing is said to differ from another in common, in consequence of differing in some respect or other, either from itself, or from something else. For Socrates differs from Plato, in being another person, and he differs from himself when a boy, and when he becomes a man, and when he does any thing, or ceases to do it. And Difference is always perceived in the various ways in which a thing is after a certain manner affected.

3. But one thing is said to differ peculiarly from another, when one thing differs from another by an inseparable Accident. And an inseparable Accident is such as an azure colour of the eye, crookedness of the nose, or a scar from a wound when it becomes scirrhous.

4. One thing also is said to differ most peculiarly from another, when it varies from it by a specific Difference. Thus, man differs from horse by a specific Difference, viz. by the quality of rational. 

5. Universally, therefore, every Difference, when connected with anything, causes that thing to be altered. But Differences which subsist in common and peculiarly, cause a thing to be different in quality: and Differences which are most peculiar, cause one thing to be another thing.

6. Hence, those Differences which cause it to be another thing, are called specific Differences; but those which cause it to be changed in quality, are simple Differences. For the Difference of rational acceding to animal, causes it to be another thing, and makes it to be a Species of animal; but the Difference of being moved makes it to differ in quality alone from that which is at rest. Hence, the one makes it to be another thing, but the other only makes it to be different in quality.

7. According to specific Differences therefore, which cause a thing to be another thing, the divisions of Genera into Species are produced, and the definitions are assigned, which consist from Genus and Differences of this kind. But according to those Differences which alone cause a thing to be different in quality, alterations alone are constituted, and the mutations of that which subsists after a certain manner.

8. Beginning therefore again, we must say, that of Differences some are separable, but others inseparable. For to be moved, and to be at rest, to be ill, and to be well, and such things as are similar to these, are separable Differences; but to have a crooked, or a flat nose, to be rational or irrational, are inseparable Differences.

9. Of inseparable Differences too, some subsist essentially, but others from Accident. Thus, rational, mortal, and to be capable of receiving science, are essentially inherent in man; but to have a crooked or a flat nose, are inherent from Accident, and not essentially.

10. The Differences therefore, which are essentially present, are assumed in the definition of Essence, and make a thing to be another thing; but those which are from Accident, are neither assumed in the definition of Essence, nor make a thing to be another thing, but cause it to be different in quality.

11. And those Differences indeed, which are essential, do not admit of the more and the less; but those which are from Accident, though they should be inseparable, admit of intension and remission. For neither is Genus more and less predicated of that of which it is the Genus, nor the Differences of Genus according to which it is divided. For these are the things which give completion to the definition of every thing. But the Essence of every thing is one and the same, and neither admits of intension nor remission. To have a crooked or a flat nose however, or to be after a certain manner coloured, admit of intension and remission.

12. Since therefore, three Species of Difference are beheld; and some indeed are separable, but others inseparable; and, of the inseparable some are essential, but others from Accident; again, of essential Differences, some are those according to which we divide Genera into Species; but others are those according to which the things divided become specific. Thus, with respect to such Differences of animal as the following; viz. animated and sensitive, rational and irrational, mortal and immortal; the Difference of animated and sensitive is constitutive of the Essence of animal; but the Difference of mortal and immortal, and also of rational and irrational, are the divisive Differences of animal; for through these we divide Genera into Species.

13. These divisive Differences however of Genera, give completion to, and constitute Species. For animal is divided by the Difference of rational and irrational, and again, by the Difference of mortal and immortal; but the Differences of rational and mortal, become constitutive of man; those of rational and immortal, of a God; and those of mortal and irrational, of irrational animals. Thus, also, since the Differences, animated and inanimate, sensitive and deprived of sense, divide Essence or substance, which is arranged in the highest place; animated and sensitive added to Essence, form animal; but animated and deprived of sense, form plant.

14. Since, therefore, the same Differences assumed in a certain respect, become constitutive; and in a certain respect become divisive; all of them are called specific.

15. And these are especially useful in the divisions of Genera, and in definitions; but this is not the case with Differences which are inseparable from Accident, and much less with those that are separable.

16. These also defining, they say Difference is that by which Species is more abundant than Genus. Thus, man has more than animal in consequence of being rational and mortal. For animal is neither any. one of these (since if it were, whence, would Species have Differences?) nor has it all opposite Differences; (because if it had, the same thing would at the same time have opposites) but as they conceive, it contains in capacity all the Differences which are under it) but possesses no one of them in energy. And thus, neither is any thing Generated from non-entities, nor will opposites subsist at once about the same thing.

17. They also define Difference as follows: Difference is that which is predicated of many things differing in Species, in answer to the question “What kind of a thing is this?”. Thus, rational and mortal, when predicated of man, are predicated in answer to the question, “What kind of a thing is man?”, and not in answer to the question, “What is man?”. For being asked “What is man?”, we appropriately answer, “an animal”; but when we are asked, “What kind of an animal is man?”, we properly reply, that “He is a rational and mortal animal.”. For since things consist from matter and form, or from things which are analogous to matter and form, as a statue is composed from brass, as matter, but from figure, as form; Thus, also man, both the common and specific consists from Genus which is analogous to matter, and from Difference which is analogous to form. This whole however, viz. animal rational mortal, is man, in the same manner as the statue there.

18. They also describe it as follows: Difference is that which is naturally adapted to separate things which are arranged under the same Genus. Thus, rational and irrational, separate man and horse, which are under the same Genus, viz. animal.

19. They likewise explain it thus: Difference is that by which every thing differs. For man and horse, do not indeed differ according to Genus; for both we and horses are animals; but the addition of rational separates us from them. We also and angels are rational, but the addition of mortal separates us from them.

20. Those however who more elegantly discuss what pertains to Difference, do not say that Difference is any thing casual which separates things under the same Genus, but they assert it to be that which contributes to the Essence and the very nature of a tiling, and which is a part of a thing. Thus, to be naturally adapted to sail is not the Difference of man, though it is the Peculiarity of man. For we may say, that of animals some are naturally adapted to sail, and others are not; separating man from other animals. But a natural ability of sailing, does not give completion to the Essence of man, nor is a part of his Essence, but is alone an aptitude of it; because it is not such a Difference, as those are which are called specific Differences. Hence, specific Differences will be those, which produce another Species, and which are assumed in explaining in what the very nature of a thing consists. And

21. Thus, much may suffice concerning Difference.

Porphyry, Introduction. Chapter 4

1. With respect to Peculiarity, they give it a fourfold division.

2. For Peculiarity is that which is an Accident to a certain Species alone, though not to every individual of that Species. Thus, it happens to a man to heal, or to geometrize.

3. It is also that which is an Accident to the whole of a Species, though not to that Species alone. Thus, it happens to man to be a biped.

4. It is likewise that which is an Accident to a certain Species alone, and to every individual of that Species, and at a certain time. Thus, it happens to every man to have grey hairs in old age.

5. And in the fourth place, it is that in which what is Accidental to one Species alone, to every individual of that Species, and always, concur; as risibility to man. For though he does not always laugh, yet he is said to be risible, not from laughing always, but from being naturally adapted to laugh. And this Peculiarity is always connascent with him, in the same manner as an aptitude to neighing is connascent with a horse.

6. They say also, that these are properly peculiarities, because they reciprocate. For if any thing is a horse, it has an aptitude to neighing; and if any thing has an aptitude to neighing, it is a horse.

Porphyry, Introduction. Chapter 5

1. Accident is that which may be present and absent, without the corruption of its subject.

2. But it receives a twofold division; for one kind of it is separable, but another inseparable. Thus, to sleep is a separable Accident; but to be black happens inseparably to a crow and an Aethiopian. It is possible however to conceive a white crow, and an Ethiopian casting off his colour, without the corruption of the subject.

3. They also define it as follows: Accident is that which may be present and not present to the same thing.

4. Likewise, that which is neither Genus nor Difference, which is neither Species, nor Peculiarity, but is always inexistent in a subject.

Porphyry, Introduction. Chapter 6

1. Having separately discussed all that was proposed, I mean, Species, Difference, Peculiarity, and Accident, we must show what things are common to them, and what are peculiar.

2. It is common therefore to all of them to be predicated, as we have said, of many things.

3. But Genus is predicated of the Species and individuals which are under it; and in a similar manner Difference. Species is predicated of the individuals which are under it; but Peculiarity is predicated of the Species of which it is the Peculiarity, and of the individuals which are under that Species. And Accident is predicated both of Species and individuals. For animal is predicated of horse and ox which are Species (of it); and also of this particular horse, and that particular ox, which are individuals. But the irrational is predicated of horse and ox, and of particular horses and oxen. Species however, such as man, is alone predicated of particulars. But Peculiarity, is predicated of the Species of which it is the Peculiarity, and of the individuals under that Species. Thus, risibility is predicated of man, and of individual men. But blackness is predicated of the Species of crows, and of individual crows, since it is an inseparable Accident. To be moved likewise, which is a separable Accident, is predicated of man and horse. Primarily, however, it is predicated of individuals; but secondarily, of those things which comprehend individuals.

Porphyry, Introduction. Chapter 7

1. But to be comprehensive of Species is common to Genus and Difference; for Difference also comprehends Species, though not all such as Genus comprehends. For rational though it does not comprehend irrational natures, as animal does, yet it comprehends angel and man which are Species.

2. Such things too, as are predicated of Genus as Genus, are also predicated of the Species under it. And such things as are predicated of Difference as Difference, are also predicated of the Species formed from it. For animal being a Genus, substance is predicated of it as of a Genus, and also animated and sensible. But these are predicated of all the Species under animal, as far as to individuals. Since also rational is Difference, the use of reason is predicated of it as of Difference. The use of reason however, is not only predicated of rational, but also of the Species under rational.

3. This likewise is common, that Genus or Difference being subverted, the things which are under them are also subverted.  For as if animal is not, horse is not, nor man, Thus, also rational not existing, there will be no animal which uses reason.

4. But it is the property of Genus to be predicated of more things than Difference, Species, Peculiarity, and Accident are predicated. For animal is predicated of man and horse, of bird and snake; but quadruped is alone predicated of animals which have four feet. Man is alone predicated of individuals; and an ability of neighing, is predicated of horse alone, and of particular horses. In a similar manner Accident is predicated of still fewer things. It is necessary however to assume the Differences by which Genus is divided, and not those which give completion to, but those which divide the Essence of Genus. 

5. Farther still, Genus comprehends Difference in capacity. For of animal one kind is rational, and another irrational; but Differences do not comprehend Genera.

6. Again, Genera are prior to the Differences which are under them.

7. Hence, they subvert Differences, but are not co-sub- verted with them. For animal being subverted, rational and irrational axe at the same time subverted. But Differences do not any longer co-subvert with themselves Genus; for though all of them should be subverted yet we may form a conception of animated sensible Essence, which is animal.

8. Farther still, Genus is predicated in answer to the question “What is this?”, but Difference is predicated in answer to the question “What kind of a thing is this?”, as we have before observed.

9. Again, there is one Genus according to every Species, as for instance, animal is the Genus of man; but there are many Differences, as, rational, mortal, capable of intellect and science, by which man differs from other animals.

10. And Genus indeed is similar to matter, but Difference to form.

11. Since however, there are other things which are common and peculiar to Genus and Difference, those which we have enumerated are sufficient.

Porphyry, Introduction. Chapter 8

1. Genus and Species possess in common, as we have said, the being predicated of many things. Species however must be assumed as Species only, and not also as Genus, if the same thing should be both Genus and Species.

2. It is likewise common to them to be prior to the things of which they are predicated.

3. And also that each of them is a certain whole.

4. They differ however, because Genus indeed comprehends Species, but Species are comprehended, and do not comprehend Genera.

5. For Genus is predicated to a greater extent than Species.

6. Again, it is necessary that Genera should be pre-supposed, and when invested with form by specific Differences, that they should give consummation to Species. Whence also Genera are prior by nature.

7. They also subvert other things together with themselves, but are not co-subverted with other things. Thus, Species existing, Genus also entirely exists; but Genus existing, it does not entirely follow that Species exists.

8. And Genera indeed, are synonymously predicated of the Species which are under them; but Species are not. Thus, predicated of Genera.

9. Farther still, Genera are more copious than Species, in consequence of comprehending the Species which are under them; but Species are more copious than Genera by their proper Differences.

10. Again, neither Species can become most General, nor Genus most specific.

Porphyry, Introduction. Chapter 9

1. It is common to Genus and Peculiarity to follow Species. For if any thing is man it is animal; and if any thing is man it is risible.

2. It is likewise common to Genus to be equally predicated of Species, and to Peculiarity to be equally predicated of the individuals which participate it. Thus, man and ox are equally animals; and Anytus and Melitus are equally risible.

3. It is also common to Genus to be synonymously predicated of its proper Species, and to Peculiarity to be synonymously predicated of the things of which it is the Peculiarity.

4. They differ however, because Genus indeed is prior, but Peculiarity posterior. For it is first necessary that animal should exist, and afterwards that it should be divided by Differences and peculiarities.

5. And Genus indeed is predicated of many Species; but Peculiarity is predicated of one certain Species, of which it is the Peculiarity.

6. Farther still, Peculiarity is reciprocally predicated of that of which it is the Peculiarity; but Genus is not reciprocally predicated of any thing. For neither does it follow if any thing is an animal, that it is a man; nor if any thing is an animal that it is risible. But if any thing is a man, it follows that it is risible; and if any thing is risible, it follows that it is a man.

7. Again, Peculiarity is inherent in the whole Species of which it is the Peculiarity and is alone and always inherent; but Genus is inherent in the whole Species of which it is the Genus, and is always inherent yet not alone.

8. Farther still, peculiarities being subverted, Genera are not subverted together with them; but Genera being subverted the Species also are subverted together with them, to which the peculiarities belong.  Hence, those things of which there are peculiarities being subverted, the peculiarities themselves are at the same time subverted.

Porphyry, Introduction. Chapter 10

1. It is common to Genus and Accident to be predicated, as we have said, of many things; whether the Accidents be separable or inseparable. For to be moved is predicated of many things; and blackness is predicated of crows, of Ethiopians, and of certain inanimate things.

2. But Genus differs from Accident in this; that Genus is prior to Species, but Accidents are posterior to Species. For though inseparable Accident should be assumed, yet that of which it is the Accident is prior to the Accident.

3. And those things indeed which participate of Genus equally participate it; but the participants of Accident do not equally participate it. For the participation of Accidents receives intension and remission; but this is not the case with the participation of Genera.

4. And Accidents indeed precedaneously subsist in individuals; but Genera and Species are by nature prior to individual Essences.

5. Genera also are predicated of the things under them, in answer to the question what a thing is; but Accidents in answer to the question, what kind of a thing it is, or how it subsists. For on being asked what kind of a thing an Ethiopian is, you reply that he is black; or how Socrates is, you reply that he is sick or well.

Porphyry, Introduction. Chapter 11

1. And thus, we have shown in what Genus differs from the other four. It happens also that each of the other four differs from the rest; so that since there are five, and each of the four differs from the others, it would seem that all the Differences which are produced will be twenty.

2. This however is not the case, but always those which are successive are con-numerated. And the second is deficient by one Difference, because it has been already assumed; the third is deficient by two Differences; the fourth by three; and the fifth by four. Hence, all the Differences will be ten; viz. four, three, two, and one. For we have shown in what respect Genus differs from Difference, Species, Peculiarity, and Accident. There are therefore four Differences. We also showed in what respect Difference differs from Genus, when we explained in what respect Genus differs from it. It remained therefore to say in what respect it differs from Species, Peculiarity, and Accident; and three Differences are produced. Again, it was said by us in what respect Species differs from Difference, when we explained in what respect Difference differs from Species. And it was shown by us in what respect Species differs from Genus, when we’ explained in what Genus differ from Species. It remained therefore to say, in what respect Species differs from Peculiarity and Accident. These therefore are two Differences. At length, it remained to be explained, in what respect Peculiarity differs from Accident; for in what respect it differs from Species, Difference and Genus, was before explained by us, in the Difference of those from these. Hence, as four Differences of Genus with respect to the rest are assumed, but three of Difference, two of Species, and one of Peculiarity with respect to Accident, all the Differences will be ten; four of which, viz. the Differences of Genus with respect to the rest, we have already shown.

Porphyry, Introduction. Chapter 12

1. It is common therefore to Difference and Species, to be participated equally; for the individuals of mankind participate equally of man, and the Difference of rational.

2. It is likewise common to them to be always present to their participants; for Socrates is always rational, and Socrates is always a man.

3. But it is the Peculiarity of Difference indeed, to be predicated in answer to the question what kind of a thing a thing is; and of Species to be predicated in answer to the question, what a thing is. For though man should be assumed as a certain kind of a thing, yet he will not be simply so, but so far as Differences acceding to Genus give subsistence to him.

4. Again, Difference is frequently seen in many Species, as quadruped in many animals which differ in Species; but Species is in the individuals alone which are under Species.

5. Farther still, Difference is prior to the Species which subsists according to it. For rational being subverted co-subverts man with itself; but man being subverted, does not subvert rational, since angel will still exist.

6. Again, Difference is conjoined with another Difference; for rational and mortal are conjoined in order to the subsistence of man; but Species is not conjoined with Species, so as that a certain other Species is Generated. For a certain horse is conjoined with a certain ass, in order to the Generation of a mule; but horse simply conjoined with ass, will not produce a mule.

Porphyry, Introduction. Chapter 13

1. Difference also and Peculiarity have this in common, that they are equally participated by their participants; for rational are equally rational animals, and risible are equally risible animals.

2. It is likewise common to both, to be always present, and. to every one. For though a biped should be mutilated, yet the term always is predicated with reference to that which is naturally adapted; since that which is risible has the always from natural adaptation, and not from always laughing.

3. But it is the Peculiarity of Difference, that it is frequently predicated of many Species; as rational, is predicated of angel and man; but Peculiarity is predicated of one Species, of which it is the Peculiarity.

4. And Difference indeed, follows those things of which it is the Difference, yet it does not also reciprocate; but peculiarities are reciprocally predicated of those things of which they are the peculiarities, in consequence of reciprocating.

Porphyry, Introduction. Chapter 14

1. It is likewise common to Difference and Accident to be predicated of many things.

2. But it is common to Difference, with inseparable Accidents, to be always present, and to every one; for biped is always present to man; and in a similar manner blackness is present to all crows.

3. They differ, however; because Difference indeed comprehends Species, but is not comprehended by them; for rational comprehends angel and man; but Accidents after a certain manner comprehend, because they are in many things; and after a certain manner are comprehended, because the subjects are not the recipients of one Accident, but of many.

4. And Difference indeed, does not admit of intension and remission; but Accidents receive the more and the less.

5. Contrary Differences likewise cannot be mingled, but contrary Accidents sometimes can be mingled. And so many are the things which Difference, and the other four possess in common, and peculiarly.

Porphyry, Introduction. Chapter 15

1. With reference to Species however, we have before shown in what respect it differs from Genus and Difference, when we explained in what respect Genus, and also in what respect Difference, differs from the rest. It now remains that we should show in what respect Species differs from Peculiarity and Accident.

2. It is common therefore to Species and Peculiarity to be reciprocally predicated of each other. For if any thing is a man it is risible; and if any thing is risible, it is a man. It has however been frequently asserted by us that risibility must be assumed according to a natural aptitude to laughter.

3. It is also common to Species and Peculiarity to be equally present. For Species are equally present to their participants; and peculiarities to the things of which they are peculiarities.

4. But Species differs from Peculiarity in this, that Species indeed may be the Genus of other things; but Peculiarity can never be the Peculiarity of other things.

5. And Species indeed subsists prior to Peculiarity; but Peculiarity accedes to Species. For the existence of man is necessary to the existence of risibility.

6. Again, Species indeed, is always present in energy with its subject; but Peculiarity is sometimes present in capacity. For Socrates is always Socrates in energy, but he does not always laugh, though he is always naturally adapted to be risible.

7. Farther still, those things of which the definitions are different, are also themselves different; but the definition of Species is, to be under Genus, to be predicated of many things, and which differ in number, in answer to the question what a thing is, and things of this kind. The definition however of Peculiarity is to be present to a thing alone, to every individual of a Species, and always,

Porphyry, Introduction. Chapter 16

1. To Species and Accident also it is common, to be predicated of many things. But other common properties are rare, because Accident, and that to which it happens, very much differ from each other.

2. The peculiarities however of each are these: of Species indeed, to be predicated of the things of which it is the Species, in answer to the question what a thing is; but of Accident to be predicated, in answer to the question “What kind of a thing is this?”, or “How does this subsist?”.

3. Likewise that every Essence or substance participates of one Species, but of many Accidents, both separable and inseparable.

4. And Species indeed are conceived prior to Accidents, though they should be inseparable Accidents; (for it is necessary that there should be a subject, in order that something may happen to it) but Accidents are naturally adapted to be of posterior origin, and have a nature which consists in being an adjunct to Essence.

5. And of Species indeed the participation is equal; but of Accident, though it should be inseparable it is not equal. For an Ethiopian may have a colour which has intension or remission according to blackness with reference to another Ethiopian.

Porphyry, Introduction. Chapter 17

1. It now remains to speak concerning Peculiarity and Accident for we have already said in what respect Peculiarity differs from Species, Difference and Genus.

2. It is common therefore to Peculiarity and inseparable Accident, not to subsist without those things in which they are beheld. For as man does not subsist without risibility, so neither can an Ethiopian subsist without blackness.

3. And as Peculiarity is present to every individual of a Species and always, thus, also inseparable Accident.

4. They differ however, because Peculiarity is present to one Species only, as risibility to man; but inseparable Accident, as blackness, is not only present to an Ethiopian, but also to a crow, to a coal, to ebony, and to certain other things.

5. Again, Peculiarity is reciprocally predicated of that of which it is the Peculiarity, and is equally present; but inseparable Accident is not reciprocally predicated.

6. The participation also of peculiarities is equal, one indeed more but another less.

7. There are indeed other things which are common and peculiar to the above-mentioned five terms, but these are sufficient for the purpose of showing their distinction and agreement.

THE END