The Lives and Opinions of Eminent Philosophers

by Diogenes Laertius

XXXII. And I have thought it best to give a general account of all the Stoic doctrines in the life of Zeno, because he it was who was the founder of the sect.

He has written a great many books, of which I have already given a list, in which he has spoken as no other of the Stoics has. And his doctrines in general are these. But we will enumerate them briefly, as we have been in the habit of doing in the case of the other philosophers.

XXXIII. The Stoics divide reason according to philosophy, into three parts; and say that one part relates to natural philosophy, one to ethics, and one to logic. And Zeno, the Cittiæan, was the first who made this division, in his treatise on Reason; and he was followed in it by Chrysippus, in the first book of his treatise on Reason, and in the first book of his treatise on Natural Philosophy; and also by Apollodorus; and by Syllus, in the first book of his Introduction to the Doctrines of the Stoics; and by Eudromus, in his Ethical Elements; and by Diogenes, the Babylonian; and Posidonius. Now these divisions are called topics by Apollodorus, species by Chrysippus and Eudromus, and genera by all the rest. And they compare philosophy to an animal, likening logic to the bones and sinews, natural philosophy to the fleshy parts, and ethical philosophy to the soul. Again, they compare it to an egg; calling logic the shell, and ethics the white, and natural philosophy the yolk. Also to a fertile field; in which logic is the fence which goes round it, ethics are the fruit, and natural philosophy the soil, or the fruit-trees. Again, they compare it to a city fortified by walls, and regulated by reason; and then, as some of them say, no one part is preferred to another, but they are all combined and united inseparably; and so they treat of them all in combination. But others class logic first, natural philosophy second, and ethics third; as Zeno does in his treatise on Reason, and in this he is followed by Chrysippus, and Archedemus, and Eudromus.

For Diogenes of Ptolemais begins with ethics; but Apollodorus places ethics second; and Panætius and Posidonius begin with natural philosophy, as Phanias, the friend of Posidonius asserts, in the first book of his treatise on the School of Posidonius.

But Cleanthes says, that there are six divisions of reason according to philosophy: dialectics, rhetoric, ethics, politics, physics, and theology; but others assert that these are not divisions of reason, but of philosophy itself; and this is the opinion advanced by Zeno, of Tarsus, among others.

XXXIV. Some again say, that the logical division is properly subdivided into two sciences, namely, rhetoric and dialectics; and some divide it also into definitive species, which is conversant with rules and tests; while others deny the propriety of this last division altogether, and argue that the object of rules and tests is the discovery of the truth; for it is in this division that they explain the differences of representations. They also argue that, on the other side, the science of definitions has equally for its object the discovery of truth, since we only know things by the intervention of ideas. They also call rhetoric a science conversant about speaking well concerning matters which admit of a detailed narrative; and dialectics they call the science of arguing correctly in discussions which can be carried on by question and answer; on which account they define it thus: a knowledge of what is true, and false, and neither one thing nor the other.

Again, rhetoric itself they divide into three kinds; for one description they say is concerning about giving advice, another is forensic, and the third encomiastic; and it is also divided into several parts, one relating to the discovery of arguments, one to style, one to the arrangement of arguments, and the other to the delivery of the speech. And a rhetorical oration they divide into the exordium, the narration, the reply to the statements of the adverse party, and the peroration.

XXXV. Dialectics, they say, is divided into two parts; one of which has reference to the things signified, the other to the expression. That which has reference to the things signified or spoken of, they divide again into the topic of things conceived in the fancy, and into those of axioms, of perfect determinations, of predicaments, of things alike, whether upright or prostrate, of tropes, of syllogisms, and of sophisms, which are derived either from the voice or from the things. And these sophisms are of various kinds; there is the false one, the one which states facts, the negative, the sorites, and others like these; the imperfect one, the inexplicable one, the conclusive one, the veiled one, the horned one, the nobody, and the mower.

In the second part of dialectics, that which has for its object the expression, they treat of written language, of the different parts of a discourse, of solecism and barbarism, of poetical forms of expression, of ambiguity, of a melodious voice, of music; and some even add definitions, divisions, and diction.