Chapter II: What is the purpose of this work? For anyone who undertakes a task without a definite goal wanders, as it were, in darkness; Since he who labors without a goal begs in everything, we will first of all speak about the purpose set for this book, so that what is said in it will be more easily assimilated. The aim is to begin with philosophy and briefly outline in this book as much knowledge as possible. Therefore, it should be called the "Source of Knowledge". Therefore I will say nothing of my own behalf, but I will set forth in a coherent manner what has been said in various places by divine and wise men. And it is better to define first of all what philosophy is.

Chapter III: On Philosophy. Philosophy is the cognition of existence as such, i.e., the cognition of the nature of being. And again: philosophy is the knowledge of Divine and human things, i.e., the visible and the invisible. Moreover, philosophy is the thought of death, both voluntary and natural. For there are two kinds of life: natural, by which we live, and voluntary, by virtue of which we are passionately attached to the present life. There are also two kinds of death: natural death, which is the separation of the soul from the body. and voluntary death, by which we, neglecting the present life, strive for the next. Then, philosophy is likeness to God. We become like God through wisdom, that is, through the true knowledge of good, and also through justice, which gives to each his own and judges impartially; finally, through holiness, which is higher than justice, i.e., through goodness and retribution with good to those who offend. Philosophy is the art of the arts and the science of the sciences. For philosophy is the beginning of all art: every art and every science were invented by it. Art, in the opinion of some, sins in some ways; science does not err in anything: but philosophy alone does not err (in general). According to others, art is something that is performed with the help of hands. A science will be any intellectual art: grammar, rhetoric, and the like. Moreover, philosophy is the love of wisdom; God is true wisdom. Thus the love of God is a true philosophy. Philosophy is divided into theoretical and practical. The theoretical, in turn, is divided into theology, physiology, and mathematics, and the practical into ethics, economics, and politics. Theoretical philosophy tends to adorn knowledge. At the same time, theology tends to consider the incorporeal and immaterial: first of all, God, the truly immaterial, and then the angels and the soul. Physiology is the knowledge of what is material and immediately accessible to us, for example, animals, plants, stones, etc. Mathematics is the knowledge of that which in itself is incorporeal, but is contemplated in the body, that is, of numbers, I say, and of the harmony of sounds, and, in addition, of the figures and movements of the luminaries. At the same time, the consideration of numbers is arithmetic, the consideration of sounds is music, and the consideration of figures is geometry; and finally, the consideration of the luminaries, astronomy. All this occupies a middle place between bodies and incorporeal things. In fact, the number itself is incorporeal, but is considered in the body, in bread, for example, or in wine, or in something like that. Practical philosophy is concerned with virtues, for it regulates morals and teaches how one's life should be organized. At the same time, if it proposes laws to one person, it is called ethics; if the whole house, it is the economy; if it is cities and countries, it is politics.

Some have tried to eliminate philosophy, saying that there is no philosophy, nor is there any knowledge or comprehension. To them we say: on what grounds do you say that there is no philosophy, no knowledge or comprehension? Is it because it has been known and comprehended by you, or because it has not been known and comprehended? If because it has been attained, then this is knowledge and comprehension for you; but if it is because it has not been known, no one will believe you, because you are reasoning about a subject of which you have not received any knowledge.

Thus, in view of the fact that there is philosophy and there is knowledge of being, we will speak of what is. But it must be known that we shall first deal with the logical part of philosophy: the latter is rather an instrument of philosophy than a part of it, for (philosophy) uses it in every proof. So, we will first talk about simple words that denote simple things through simple meanings. And having first explained the meaning of words (lexews), let us consider in the same way what concerns speeches.

Chapter IV: Of Being, Substance, and Accident Being (to on) is a common name for everything that exists. It is divided into substance and accident. Substance (ousia) is something most important, since it has existence in itself, and not in another. Accident (sumbebhkos) is that which cannot exist in itself, but is contemplated in substance. Substance is the subject (upokeimenon), as it were, the matter of things. Now accident is that which is contemplated in substance as a subject, e.g., copper and wax are substances, and figure, form, and colour are accidents, and body is substance, and its colour is accident. It is not the body that is in color, but the color in the body, and not the soul in knowledge, but knowledge in the soul, and not brass and wax in figure, but figure in wax and brass. They do not speak; the body of color, but the color of the body; not the soul of knowledge, but the knowledge of the soul; not a wax figure, but a wax figure. Color, knowledge, and figure change, but body, soul, and wax remain the same, because the substance does not change. Moreover, the substance and matter of the body are one: the colors are many. It is the same with everything else: the subject is substance; That which is contemplated in the subject, i.e., substance, is an accident.

Substance is defined in this way: substance is a self-existent thing that does not need another for its existence. Accident, on the other hand, is that which cannot exist in itself, but has its existence in another. Thus the substance will be God and all creation, although God is a pre-existent substance. There are also essential qualities that we will talk about.

Chapter V. About sound. Since we intend to reason about every purely (aplws) philosophical sound (fwnh), we must first determine what sound philosophy deals with. Beginning our speech with the consideration of sound, we say: a sound can be either insignificant (ashmos) or significant (shmantikh). An insignificant sound is one that does not mean anything; significant — the one that signifies something. Further, an insignificant sound, in turn, can be either inarticulate or articulate. An inarticulate sound is one that cannot be written; articulate is that which can be written. Thus there is an inarticulate and insignificant sound, such as that produced by stone or wood, for it cannot be written down, and signifies nothing. There is a sound that is insignificant and articulate, for example, "skindaps": for it can be written, but it does not mean anything; There was no Skindaps, and there is none. Philosophy does not care about insignificant sounds, whether inarticulate or articulate. In turn, a significant sound can be either articulate or inarticulate. An inarticulate significant sound would be, for example, the barking of dogs: it denotes a dog, since there is a dog's voice; in the same way it signifies someone's presence; But this is an inarticulate sound, so it is not written. And this sound of philosophy does not care. An articulate significant sound can be either general or particular [singular]. A common sound would be, for example, "man"; private — Peter, Paul. And there is no concern for the particular sound of philosophy. But (philosophy deals) with a sound that is significant, articulate, conciliar, i.e., general, expressed in application to many objects.

This sound, in turn, is either essential (ousiwdhs) or applied to the essence (epousiwdhs). Essential is that sound which expresses the substance or nature of things; and that which is applied to the essence is that which expresses accidents. For example: man is a mortal rational animal. All these will be significant sounds. For if you take any of these things away from a man, he will not be a man. And if you say that he is not an animal, then he is no longer a man; and if you say that he is not intelligent, then he is no longer a man; in the same way, if you say that he is not mortal, he is not a man; for every man is an animal, and rational, and mortal. Therefore (these sounds) are called essential because they complete the nature of man, and it is impossible for man to exist outside of them. In like manner, in every thing, that which constitutes its nature is called essential; and what is applied to the essence are accidents, which may or may not be in the subject, such as a man or a horse, or something else like that, for example, white. For whether a man be white or black, he will nevertheless remain a man. This and the like are called those which are applied to the essence, or accidents, which we may have either these or their opposites.

Essential sound denotes either what a thing is or what this thing is. For example, answering the question of what a human being is, we say: animal. Then, asked what kind of animal, we say: rational, mortal. The essential sound that shows what an object is is called difference (diafora); but he who shows what an object is designates either many species and constitutes a genus, or many individuals differing from each other in number, but in no case in species, and constitutes a species. The first, i.e., the genus, is, for example, substance, for substance signifies man, horse, and ox, because each of these beings is called and is substance, but the one is one species, the other another. The second, i.e., species, is, for example, man, for this word signifies many, or rather all individuals, who differ from each other in number, for the one is Peter and the other is Paul, and they are not one, but two, but in kind, that is, in nature, they do not differ. In fact, they are all called and are people.

Thus there is the most particular [individual, as opposed to genus and species], differing from each other in number, e.g., Peter, the individual, and also the person and hypostasis (prosopon kai upostasis). It denotes someone definite. Thus, when we are asked; "Who is this (man)," we say, "Peter." This is also indicated by the expressions "other" — for one is Peter and the other — Paul — "he," "this," "that"—they are applied to the individual who exists in himself, and the like. This word embraces Peter, Paul, and all individual people. The Holy Fathers call the species nature (fusis) and essence (ousia) and form (morfh). That which embraces a multitude of species is called a genus, e.g., "animal," because it embraces man, ox, horse, and is more general than a species. The Holy Fathers call both species and genus nature, form, image, essence. Through the species, that is to say, nature, essence, form, it is not this or that individual, not this or that difference, but this or that substance that is posited. Thus we call man one entity, the horse another, but not one or another individual. As for the species, it is said: this, it, that, and the like, i.e., that which answers the question: "What is an object?" As for what is applied to the essence, it belongs either to one species or to many. If it belongs to one species, it is called a property; For example, the ability to laugh, which belongs to one person, the ability to neigh, which belongs to one horse. If it belongs to many species, it is an accident, for example, whiteness, for it belongs to man, and to horses, and dogs, and many other species. Such are the five names to which every philosophical name is reducible, and we need to know what each of them signifies, and in what ways they resemble each other, and in what they differ. These names are: genus, species, difference, property, and accident.

A genus is that which is expressed, i.e., said and named, in relation to many objects differing from each other in kind, to the question: What is an object? For to speak is to be said about something.

A species is that which is expressed in relation to many objects differing from each other in number, to the question: What is an object?

Difference is that which is said in relation to many objects that differ from each other in kind, to the question: What is the object? and is accepted in the definition as an essential feature. The difference cannot be and not be in one and the same form, but must necessarily be in the form to which it belongs. Being present in it, it preserves it: in its absence, it destroys it. In the same way, it is impossible that both difference and its opposite should be combined in one form. For example, rationality cannot but belong to man, for an irrational being is no longer a man. Being present, rationality constitutes the nature of man, and when absent, it destroys, for an irrational being is no longer a man. It should be noted that difference is called essential, natural (fusikh), component (sustatikh), dividing, as well as specific difference, essential quality and natural property of nature. Philosophers very aptly call it difference, since it is the most special and is the expression of the essence to which it belongs.

A property is that which belongs to one species, to all things, and is capable of being addressed, such as the ability to laugh. In fact, every man is capable of laughing, and every creature capable of laughing is a man.