There is another way of dividing, namely, into objects originating from one object and relating to one object. From the one, namely, medicine, both the medical book and the medical instrument are derived, for they are called medical from one subject, medicine. To one object belong a medicine useful for health and food useful for health, for they have in mind one and the same object – health. As for objects derived from the same object, some of them derive their name from a certain cause, for example, the image of a man derives its name from a true cause, i.e., man; others because they were invented by someone: for example, a medical knife and similar objects.

Such is the general division of objects, according to which everything that admits of division can be divided: either as a genus into species, or as a species into individuals, or as a whole into parts, or as a homonymous name into signified differences, or as substance by accident, or as accident by substance, or as accident by accident, or as objects belonging to and relating to one and the same object. However, some do not recognize the division of a species into individuals as a division, preferring to call it calculus, because a division has two, three, very rarely four terms; but the species is divided into an infinite number of members; for individual people, for example, are an infinite number.

It is to be observed that no method of division [except the last] makes it possible to see what in the terms of division is antecedent in nature and what is subsequent, as well as what is higher and what is lower. But when we are divided according to descent from the same object or in relation to the same object, it is possible to see what is antecedent in nature and what is subsequent, and also what is higher and what is lower, from this proceeds its origin and name.

Chapter VII: Of the Antecedent by Nature. That which is posited together with the other, but does not posit it, which along with itself eliminates the other, but is not eliminated along with it, is called antecedent by nature. For example, the animal is by nature prior to man, for since the animal is eliminated and does not exist, then man will not necessarily exist, since man is an animal. If man is destroyed and does not exist, the existence of an animal is possible, because there will be a horse, a dog, and similar creatures that are animals. On the other hand, if man is posited, then an animal is certainly also posited, for man is an animal. But if an animal is posed, then a man is not necessarily posed, but a horse, a dog, and something like that can be relied upon, for they also are animals. Therefore Peter does not precede Paul by nature, or the rational animal precedes the irrational, for when Peter is removed and does not exist, Paul will exist, and when Paul is posited, Peter is not put together, just as when Peter is posited, Paul is not put together. In the same way, Peter is no more, that is, no more fully human or animal, than Paul, just as Paul is no more than Peter. But one remedy is more effective than another, and one medical book is more useful than another.

Chapter VIII. About the definition. A definition is a short speech expressing the nature of the subject, i.e., speech denoting this nature with a few words. For example, man is a rational animal, mortal, capable of understanding and comprehension. Many of the people have composed broad words about the nature of man, that is, long and pompous, but since they are not distinguished by brevity, they are therefore not definitions. On the other hand, there are also short words, such as sayings (apofqegmata), but since they do not express the nature of a thing, they are not definitions. And a name. Though it often expresses the nature of the subject matter, yet it is not a definition, for a name is one word (lexis), and a definition is speech (logos), and speech is composed of at least two distinct words. [A term is a name explained, and a name is a term in a condensed form]. The definition is made up of the genus and of the constituent (sustatikon), i.e., essential (ousiwdwn) differences. This can be seen in the definition of an animal: an animal is an animate substance possessing the faculty of perception. In this definition, substance is a genus, and animate and perceptual power are forming differences. It is composed (definition) of matter and form. For example, a statue is something that is made of copper and depicts a person. Thus, copper is matter, and "depicts man" is the form of a statue. In this case, matter corresponds to gender, and form corresponds to differences. A definition is also drawn up from the subject under study and the goal. For example, medicine is an art that has human bodies as its object, and has health as its goal. Here the subject of medicine is human bodies, and the goal is its health.

Description, on the other hand, is composed of non-essential attributes, i.e., properties and accidents. For example; Man is an animal capable of laughing, having an upright gait and flat nails. All these are insignificant signs. For this reason the description is called (in Greek) (upografh), since it gives a shadow of the object, as it were, and expresses not the essential being, but that which accompanies it. A descriptive definition is a mixture of essential and non-essential features of an object. For example, man is a rational animal with an erect gait and flat nails.

The definition (in Greek) is called (orismos) from the metaphor of land boundaries. As a boundary separates the property of each man from the property of another, so definition separates the nature of each thing from the nature of another.

The virtue of the definition is not to be scarce and not to abound in words. Its drawback is the scarcity or excess of words. A perfect definition will be one that admits of handling the object defined, and an imperfect definition is one that does not admit of being addressed. A definition that is poor in words does not allow for address. When a definition abounds in words, it is already a definable thing: but when it is scarce in words, it abounds in objects. [Thus it may be said that nature has invented a wonderful contrivance: scarcity abounding and wealth concealing scarcity.] For example, the perfect definition of man would be the following definition: man is a rational, mortal animal. This definition admits of conversion, for every rational, mortal animal is a man, and every man is a rational, mortal animal. If one word is omitted from this definition, then it will be broader than the object defined—for example, man is a rational animal. In this definition, one word is omitted, since I did not add: mortal. Therefore it abounds in objects, for man alone is a rational animal, but also an angel, and therefore it does not admit of conversion. But if I say: Man is a rational animal, mortal, and learned, then this definition also does not admit of conversion, for it abounds in words, since it is said: learned. Therefore, it is already a definable object, for it does not determine every person, but only scientists. Indeed, every rational, mortal and learned animal is a man, but not every man is a rational, mortal and learned animal, for not every man is a scientist.

Thus, those definitions will be perfect that allow the treatment of the object defined. But since a property also admits of the treatment of the object to which it belongs, for if a certain being is a man, it is also capable of laughing, and if it is capable of laughing, it is also a man, we must, adding to the definition given before, say that perfect definitions are those which are composed of genus and constitutive differences, in which no more and no less is said. than it should be, and which allow the treatment of what is defined. In the same way (perfect determinations) will be those which are composed of object and purpose, as well as of matter and form. Sometimes definitions are also (perfect) which consist of one object, namely, when the object is not subject to another art, as glass is not subject to the art of glass, and of one purpose, when this end cannot be the end of other arts, as is the case with shipbuilding. From all this, it should be concluded that the perfection of the definition lies in its ability to be addressed.

Название «определение» (orismos) отличается от названия «термин» (oros) тем, что первое уже, а второе шире. В самом деле «термин» (oros) обозначает и земельную границу, и решение, например, когда говорим wrisen basileus (царь решил). Точно также он означает то, на что разлагается посылка, как мы это, с Божьей помощью, узнаем потом. Обозначает оно и определение; определение же обозначает только краткую речь, выражающую природу подлежащей вещи.

Следует принять к сведению, что определение возможно только в отношении субстанции и ее видов. Что же касается индивида и акциденций, то в отношении их определение невозможно, а только описание, так как определение составляется из рода и образующих разностей, описание же — из несущественных признаков.

Глава IX. О роде. В отношении омонимов следует доискиваться ответа на следующие три вопроса: является ли известное название омонимом, сколько предметов оно обозначает и о каком из них идет речь. Но прежде нужно сказать, что такое омоним. С омонимом мы имеем дело тогда, когда два предмета или большое число их имеют одно имя, при этом каждый из них обозначает нечто различное и имеет различную природу, принимая различные определения.

Так обстоит дело и в данном случае в отношении рода, ибо род принадлежит к числу омонимов. Во–первых, род употребляется для обозначения происхождения из определенного отечества и от определенного родителя, причем и в том, и другом случае понимается двояко: в близком н отдаленном смысле. Слово род употребляется для обозначения близкого отечества: например, происходящий из Иерусалима, называется иерусалимлянином; для обозначения происхождения из дальнего отечества: например, происходящий из Палестины называется палестинским. Подобным же образом род употребляется для обозначения происхождения от близкого родителя: например, когда Ахиллес, бывший сыном Пелея, называется Пелидом, и для обозначения происхождения от отдаленного предка. например, когда тот же Ахиллес по деду Эаку называется Эакидом, ибо Эак был отцом Пелея. Далее родом называется отношение родоначальника ко многим происшедшим от него людям: например, все ведущие свое происхождение от Израиля, называются израильтянами. Рассмотренные значения слова род философии не касаются.

Далее, родом называется то, чему подчиняется вид. Например, животному подчиняется человек, лошадь и другие виды. Поэтому животное есть род. Об этом–то роде и говорят философы. Определяя его, говорим: род есть то, что сказывается в отношении многих и различающихся по виду предметов и отвечает на вопрос: что есть предмет? Например, животное как род сказывается в отношении человека, лошади, вола и многих других существ, различающихся между собой по виду, и отвечает на вопрос: что есть предмет? В самом деле, один вид человека, другой лошади и третий вола. Род высказывается на вопрос: что есть предмет? Когда нас спрашивают, что такое человек, мы отвечаем: животное. Так же обстоит дело и с лошадью, ибо когда нас спрашивают, что такое лошадь, мы говорим: животное. Таким образом, род есть то, чему подчиняется вид [и снова: род есть то, что разделяется на виды]. В самом деле, род разделяется на виды, является более общим, чем вид, обнимает виды и есть высшее в сравнении с ними понятие.