Epicurus and the Epicureans

What is now known about Epicurus (341 - 270) depends primarily on three letters Diogenes Laertius (3rd century CE) preserves in Book X of his Lives of the Philosophers: Letter to Herodotus (which outlines the Epicurean philosophy of nature) Letter to Pythocles (which discusses natural phenomena in the sky), and Letter to Menoeceus (which outlines the Epicurean position on happiness).

Diogenes Laertius structures his Lives of the Philosophers (in ten books) according to lines of succession. His life is unknown, and his point of view and motivation in his writing is unclear. In addition to the letters Diogenes Laertius preserves, Cicero (106 - 43) discusses Epicurus and the Epicureans. His discussion is often polemical.

Letter to Herodotus. Lives of the Philosophers X.34-83. Excerpts.

• Memory of the principal doctrines is necessary for happiness
• The inquiry into nature is necessary for happiness. It relieves the anxiety that accompanies superstition
• Perception is always true. Error comes from uncritical acceptance of the thoughts perception occasions

"Epicurus to Herodotus, greeting. For those who are unable to study carefully all my physical writings or to go into the longer treatises at all, I have myself prepared an epitome of the whole system, Herodotus, to preserve in the memory (μνήμην) enough of the principal doctrines, to the end that on every occasion they may be able to aid themselves on the most important points, so far as they take up the study of physics (περὶ φύσεως θεωρίας). Those who have made some advance in the survey of the entire system ought to fix in their memories (μνημονεύειν) under the principal headings an elementary outline of the whole treatment of the subject. For a comprehensive view is often required, the details but seldom. To the former, then--the main heads--we must continually return, and must memorize (μνήμῃ) them so far as to get a valid conception of the facts, as well as the means of discovering all the details exactly when once the general outlines are rightly understood and remembered (μνημονευομένων).... [S]ince such a course is of service to all who take up the inquiry into nature (φυσιολογίᾳ), I recommend constant activity in natural science; and with this sort of activity more than any other I bring calm to my life (μάλιστα ἐγγαληνίζων τῷ βίῳ). This is why I have prepared for you just such an epitome and manual of the doctrines as a whole" (Diogenes Laertius, Lives of the Philosophers X.35-37).

"Falsehood and error always depend upon the intrusion of opinion confirmation or the absence of contradiction, which fact is afterwards frequently not confirmed [following a certain movement in ourselves connected with, but distinct from, the mental picture presented—which is the cause of error.] For the presentations which, e.g., are received in a picture or arise in dreams, or from any other form of apprehension by the mind or by the other criteria of truth, would never have resembled what we call the real and true things, had it not been for certain actual things of the kind with which we come in contact. Error would not have occurred, if we had not experienced some other movement in ourselves, conjoined with, but distinct from, the perception of what is presented. And from this movement, if it be not confirmed or be contradicted, falsehood results; while, if it be confirmed or not contradicted, truth results. And to this view we must closely adhere, if we are not to repudiate the criteria founded on the clear evidence of sense, nor again to throw all these things into confusion by maintaining falsehood as if it were truth" (Diogenes Laertius, Lives of the Philosophers X.50-52).

"[W]e must hold that to arrive at accurate knowledge of the cause of things of most moment is the business of the inquiry into nature (φυσιολογίας), and that happiness (μακάριον) depends on this (viz. on the knowledge of celestial and atmospheric phenomena), and upon knowing what the heavenly bodies really are, and any kindred facts contributing to exact knowledge in this respect" (Diogenes Laertius, Lives of the Philosophers X.78).

"[T]he greatest anxiety of the human mind arises through the belief that the heavenly bodies are blessed and indestructible, and that at the same time they have volitions and actions and causality inconsistent with this belief ; and through expecting or apprehending some everlasting evil, either because of the myths, or because we are in dread of the mere insensibility of death, as if it had to do with us ; and through being reduced to this state not by conviction but by a certain irrational perversity, so that, if men do not set bounds to their terror, they endure as much or even more intense anxiety than the man whose views on these matters are quite vague. But freedom from disturbance (ἀταραξία) means being released from all these troubles and cherishing a continual remembrance (μνήμην) of the highest and most important truths. Hence we must attend to present feelings and sense perceptions, whether those of mankind in general or those peculiar to the individual, and also attend to all the clear evidence available, as given by each of the standards of truth. For by heeding them we shall rightly trace to its cause and [in this way] banish the source of disturbance and dread, accounting for celestial phenomena and for all other things which from time to time befall us and cause the utmost alarm to the rest of mankind" (Diogenes Laertius, Lives of the Philosophers X.81-82).

Letter to Pythocles. Lives of the Philosophers X.83-116. Excerpts.

• The importance of memory
• The inquiry into nature is necessary for happiness only because it relieves the anxiety that accompanies myth and superstition

"In your letter to me, of which Cleon was the bearer, you continue to show me affection which I have merited by my devotion to you, and you try, not without success, to recall (μνημονεύειν) the considerations which make for a happy life (μακάριον βίον). To aid your memory (μνημονεύῃς) you ask me for a clear and concise statement respecting celestial phenomena ; for what we have written on this subject elsewhere is, you tell me, hard to remember (δυσμνημόνευτα), although you have my books constantly with you. I was glad to receive your request and am full of pleasant expectations. We will then complete our writing and grant all you ask. Many others besides you will find these reasonings useful, and especially those who have but recently made acquaintance with the true story of nature and those who are attached to pursuits which go deeper than any part of ordinary education. So take (διάλαβε) them well, and holding them in your memory (μνήμης), take them along with the short epitome in my letter to Herodotus" (Diogenes Laertius, Lives of the Philosophers X.84-85).

"In the first place, remember that, like everything else, knowledge of celestial phenomena, whether taken along with other things or in isolation, has no other end in view than peace of mind and firm conviction (ἀταραξίαν καὶ πίστιν βέβαιον), just as with the rest [of physics]" (Diogenes Laertius, Lives of the Philosophers X.85).

"All this, Pythocles, you should keep in mind (μνημόνευσον); for then you will escape a long way from myth..." (Diogenes Laertius, Lives of the Philosophers X.116).

Letter to Menoeceus. Lives of the Philosophers X.121-135. Excerpts.

• The four-fold remedy (τετραφάρμακος)
• The good life is one of enlightened moderation
• Holding the truth about the good in mind eliminates anxiety and provides pleasure

"Let no one be slow to seek wisdom (φιλοσοφεῖν)..." (Diogenes Laertius, Lives of the Philosophers X.122).

"Accustom thyself to believe that death is nothing to us, for good and evil imply sentience (πᾶν ἀγαθὸν καὶ κακὸν ἐν αἰσθήσει), and death is the privation of all sentience; therefore a right understanding that death is nothing to us makes the mortality of life enjoyable (ἀπολαυστὸν)..." (Diogenes Laertius, Lives of the Philosophers X.124).

"We must also reflect that of desires some are natural, others are groundless; and that of the natural some are necessary as well as natural, and some natural only. And of the necessary desires some are necessary if we are to be happy (εὐδαιμονίαν), some if the body is to be rid of uneasiness, some if we are even to live. He who has a clear and certain understanding of these things will direct every preference and aversion toward securing health of body and tranquillity of mind (τὴν τοῦ σώματος ὑγίειαν καὶ τὴν τῆς ψυχῆς ἀταραξίαν), seeing that this is the sum and end of a blessed life (τοῦτο τοῦ μακαρίως ζῆν ἐστι τέλος). For the end of all our actions is to be free from pain and fear, and, when once we have attained all this, the tempest of the soul is laid; seeing that the living creature has no need to go in search of something that is lacking, nor to look for anything else by which the good of the soul and of the body will be fulfilled. When we are pained because of the absence of pleasure, then, and then only, do we feel the need of pleasure. Wherefore we call pleasure (ἡδονὴν) the starting-point and goal of a blessed life" (Diogenes Laertius, Lives of the Philosophers X.127-129).

"When we say, then, that pleasure is the end and aim, we do not mean the pleasures of the prodigal or the pleasures of sensuality, as we are understood to do by some through ignorance, prejudice, or wilful misrepresentation. By pleasure we mean the absence of pain in the body and of trouble in the soul (τὸ μήτε ἀλγεῖν κατὰ σῶμα μήτε ταράττεσθαι κατὰ ψυχήν). It is not an unbroken succession of drinking-bouts and of revelry, not sexual love, not the enjoyment of the fish and other delicacies of a luxurious table, which produce a pleasant life ; it is sober reasoning, searching out the grounds of every choice and avoidance, and banishing those beliefs through which the greatest tumults take possession of the soul" (Lives of the Philosophers X.131-132).

Who, then, is superior in thy judgement to such a man? He holds a holy belief concerning the gods, and is altogether free from the fear of death. He has diligently considered the end fixed by nature, and understands how easily the limit of good things can be reached and attained, and how either the duration or the intensity of evils is but slight" (Diogenes Laertius, Lives of the Philosophers X.133).

"Exercise (μελέτα) thyself in these and kindred precepts day and night, both by thyself and with him who is like unto thee; then never, either in waking or in dream, wilt thou be disturbed, but wilt live as a god among men" (Diogenes Laertius, Lives of the Philosophers X.135).

• The rejection of dialectic

• Against rationalism in epistemology

"They reject dialectic (διαλεκτικὴν) as superfluous: holding that the physicists (φυσικοὺς) should be content to employ the ordinary terms for things" (Diogenes Laertius, Lives of the Philosophers X.31).

"[T]hey will not get Epicurus, who despises and laughs at the whole of dialectic,..." (Cicero, Academica II.97).

"Turn next to the second division of philosophy, the department of Method and of Dialectic, which is termed λογική. Of the whole armour of Logic your founder, as it seems to me, is absolutely destitute. He does away with Definition; he has no doctrine of Division or Partition; he gives no rules for Deduction or Syllogistic Inference, and imparts no method for resolving Dilemmas or for detecting Fallacies of Equivocation. The Criteria of reality he places in sensation..." (Cicero, On Ends I.22).

The Canon (Κανών, "rule, standard")

• Preconceptions are memories
• Confirmation and disconfirmation

"Now in [the now lost] The Canon Epicurus affirms that our perceptions and preconceptions and our feelings (αἰσθήσεις καὶ προλήψεις καὶ τὰ πάθη) are the criteria of truth (κριτήρια τῆς ἀληθείας)..." (Diogenes Laertius, Lives of the Philosophers X.31).

"[Nothing can] refute perceptions or convict them of error: one cannot convict another and kindred perception, for they are equally valid.... [N]or again can reason (λόγος) refute them, for reason is wholly dependent on sensation-perceptions.... Moreover, all our notions (ἐπίνοιαι) are derived from perceptions, either by actual contact or by analogy, or resemblance, or composition, with some slight aid from reasoning" (Diogenes Laertius, Lives of the Philosophers X.31-32).

"By preconception (πρόληψιν) they mean a cognition or a right opinion or notion, or universal idea stored in the mind; that is, a recollection of an external object often presented (κατάληψιν ἢ δόξαν ὀρθὴν ἢ ἔννοιαν ἢ καθολικὴν νόησιν ἐναποκειμένην, τουτέστι μνήμην τοῦ πολλάκις ἔξωθεν φανέντος), e.g. Such and such a thing is a man..." (Diogenes Laertius, Lives of the Philosophers X.33).

"For what nation or what tribe of men is there but possesses untaught some 'preconception' of the gods? Such notions Epicurus designates by the word πρóληψιν, that is, a sort of preconceived mental picture of a thing, without which nothing can be understood or investigated or discussed" (Cicero, On the Nature of Gods I.16).

"Opinion (δόξαν) they also call a taking up (ὑπόληψιν), and declare it to be true and false; for it is true if it is subsequently confirmed or if it is not contradicted by evidence, and false if it is not subsequently confirmed or is contradicted by evidence. Hence the introduction of the phrase, 'that which awaits' confirmation, e.g. to wait and get close to the tower and then learn what it looks like at close quarters" (Diogenes Laertius, Lives of the Philosophers X.34).

"Of opinions, then, according to Epicurus, some are true, others false; the true being those which testify for, and not against, the evidence of sense, and the false those which testify against, and not for, that evidence. And confirmatory testimony is apprehension by means of evidence that the thing opined is of such a sort as it was opined to be—as when, for example, on the approach of Plato from afar I guess and opine, because of the distance, that it is Plato, and when he has drawn near the fact that he is Plato is further testified—the distance being reduced—and is confirmed by actual evidence of sense. And lack of contrary testimony is the congruity of the supposed and opined non-evident object with the apparent—as when Epicurus says that void exists, which is a thing non-evident, and this is supported by an obvious fact, namely motion; for if void does not exist, neither ought motion to exist, the moving body having no place into which to pass over, owing to the fact that all things are full and close-packed; so that, since motion exists, the apparent does not give testimony that contradicts the opined non-evident fact. But contrary testimony is something which conflicts with lack of contrary testimony; for it is the joint-refutation of the apparent fact and the supposed non-evident fact,—as when, for instance, the Stoic says that void does not exist, asserting something non-evident, and jointly with this supposed fact the apparent fact, by which I mean motion, is necessarily refuted; for if void does not exist, of necessity motion does not exist either, according to the argument we have already set out. So likewise lack of confirmatory testimony is opposed to confirmatory testimony; for it is the impression due to sense-evidence that the thing opined is not such as it was opined to be; as, for instance, when someone is approaching from afar and we guess, because of the distance, that it is Plato, but when the distance is reduced we learn by evidence that it is not Plato. Such an occurrence is lack of confirmatory testimony; for the thing opined was not confirmed by the apparent fact. Hence confirmatory testimony and lack of contrary testimony form a criterion of the truth of a thing, but lack of confirmatory testimony and contradictory testimony of its falsehood. And the base and foundation of all is the evidence of sense" (Sextus Empiricus, Against the Logicians I.211-216).

• The criteria for choice: pleasure and pain

• The good and bad are pleasure and pain

"They affirm that there are two states of feeling, pleasure and pain (ἡδονὴν καὶ ἀλγηδόνα), which arise in every animate being, and that the one is favourable (οἰκεῖον) and the other hostile (ἀλλότριον) to that being, and by their means choice and avoidance (αἱρέσεις καὶ φυγάς) are determined (κρίνεσθαι)" (Diogenes Laertius, Lives of the Philosophers X.34).

"We are inquiring,then, what is the final and ultimate good (extremum et ultimum bonorum), which as all philosophers (philosophorum) are agreed must be of such a nature as to be the end to which all other things are means, while it is not itself a means to anything else. This Epicurus finds in pleasure; pleasure he holds to be the chief good, pain the chief evil. This he sets out to prove as follows: Every animal, as soon as it is born, seeks for pleasure, and delights in it as the chief good, while it recoils from pain as the chief evil, and so far as possible avoids it. This it does as long as it remains unperverted, at the prompting of nature's own unbiased and honest verdict. Hence Epicurus refuses to admit any necessity for argument or discussion (ratione neque disputatione) to prove that pleasure is desirable and pain to be avoided. These facts, he thinks, are perceived by the senses (Sentiri haec putat), as that fire is hot, snow white, honey sweet, none of which things need be proved by elaborate argument (exquisitis rationibus): it is enough merely to draw attention to them" (Cicero, On Ends I.29-30).

The Stoics

The writings of the early Stoics (Zeno, Cleanthes, and Chrysippus) have been almost completely lost.

Sources for information about Stoicism

Cicero (106 - 43 BCE)

Knowledge of what the early Stoics thought depends heavily on the discussions in Cicero . Toward the end of his life in 46 - 44, having been sidelined from politics, he wrote a series of works to present philosophy (which had been done in Greek) in his native Latin. He describes his intention in On Ends I.1-4.

Academica is the most important of these works. It discusses the Stoics and the Academic Skeptics on the possibility of knowledge.

Academica is reconstructed from fragments of two works. The first (Lucullus or Academica Priora) consists in the now lost Catulus and the extant Lucullus. The second (Varro or Academica Posteriora) consists in the Academic Books, of which only part of the first book is extant. Academica I is what remains of the Academic Books. Academica II is the Lucullus. Academica I (Varro) consists mostly in Varro's speech on the history of philosophy from the point of view of Antiochus (Academica I.15–42) and Cicero's alternative from the point of view of the Academic Skeptics (Academica I.44-46). Academica (Lucullus) consists mostly in Lucullus' speech on the Stoics (Academica II.11–62) and Cicero's defense of the Academic Skeptics in reply (Academica II.64–147).

On Divination (in two books) contains arguments for divination and refutations of these arguments.

On Ends (in five books) is a critical discussion of the main ethical views of is day. There are separate dialogues devoted to each of the three views. The first (in books one and two) sets out Epicurean ethics and refutes it from the point the Stoics. The second dialogue (in books three and four) sets out Stoic ethics and refutes it from the point of view Antiochus.

On the Nature of the Gods sets out (in three books) the theological views of the Epicureans, Stoics, and Academics.

Stoic Paradoxes (in six essays) discusses some of the more striking Stoic doctrines. The essays are intended as amusing popularizations, not serious works in philosophy.

Tusculan Disputations (in five books) discusses the fear of death, the endurance of pain, the alleviation of distress, the remaining disorders of the soul, and the sufficiency of virtue for a happy life. (The discussions in the Tusculan Disputations take place in Cicero's villa in Tusculum (a now ruined Roman city about 14 miles south of Rome).)

Seneca (4 BCE-65 CE)

Seneca is a late Stoic. His work in philosophy is concerned primarily with the application of Stoic ethics.

Epictetus (55-135 CE)

Epictetus is a late Stoic. He wrote nothing. His Manual and Discourses were compiled by his student Arrrian. "I attempted to write down in his own words as nearly as possible, for the purpose of preserving them as memorials to myself afterwards of the thoughts and the freedom of speech of Epictetus" (Discourses. "Arrian to Lucius Gellius").

"[I]n a manner this is philosophizing (φιλοσοφεῖν), to seek how it is possible to employ desire and aversion without impediment" (Discourses III.14).

Galen (130-210 CE)

Galen of Pergamum is a Greek physician and philosopher. He wrote the first six (of the nine) books of On the Doctrines of Hippocrates and Plato in 162-166. His aim is to show that Hippocrates and Plato agreed and were correct about the faculties of animals. The work is largely polemical. In books III-V, he attacks Chrysippus' understanding of the soul and conception of the passions.

Sextus Empiricus (2nd or 3rd century CE)

Sextus Empiricus was a physician (in the empirical tradition) and philosopher (a Pyrrhonian skeptic). His surviving works include the Outlines of Pyrrhonism and Against the Mathematicians (Adversus Mathematicos). This later work (referred to by the abbreviation M) is in eleven books that have separate titles. Against the Logicians I and II is M VII and VIII. Against the Ethicists is M XI.

Aëtius (1st or early 2nd century CE) in Placita Philosophorum, Pseudo-Plutarch (2nd century CE)

Placita Philosophorum (Views of the Philosophers) (once wrongly attributed to Plutarch) sets out five books of views of the philosophers on physics. Stobaeus (5th century CE) and Theodoret (5th century CE) preserve parts of this same work. Theodoret names (the otherwise unknown) Aëtius as the source. (The tradition of works of the views of the philosophers on physics begins with Theophrastus, Aristotle's successor in the Lyceum. Diogenes Laertius lists "sixteen books of Physical Opinions" in the catalog of works he attributes to Theophrastus (Lives of the Philosophers V.2.48).)

Arius Didymus (1st BCE) in Anthology, Stobaeus (5th century CE)

John of Stobi compiled an anthology of extracts from philosophers for the education of his son. Book II begins with "The views of Zeno and the rest of the Stoics about the ethical part of philosophy" (II.7.5-12). He does not mention the source for this extract. It is conjectured to be Arius Didymus (who was active in the time of the Roman emperor Augustus).

• Cicero. Academica. On Divination. On Ends. Stoic Paradoxes. Tusculan Disputations.

• Impression, cognitive impression
• Assent
• Cognition, opinion, knowledge

  "Here first of all he [Zeno] made some new pronouncements about perception itself, which he held to be a combination of a sort of impact offered from outside (which he called φαντασίαν and we may call an impression, and let us retain this term at all events, for we shall have to employ it several times in the remainder of my discourse),—well, to these impressions received by the senses he joins the act of mental assent which he makes out to reside within us and to be a voluntary act. He held that not all impressions are trustworthy but only those that have a 'manifestation,' peculiar to themselves, of the objects presented; and a trustworthy impression, being perceived as such by its own intrinsic nature, he termed ‘graspable’ [= a 'cognitive impression']—will you endure these coinages?
   Indeed we will,for how else could you express καταληπτόν?
  But after it had been received and accepted as true, he termed it a 'grasp' [= a 'cognition'] resembling objects gripped in the hand—and in fact he had derived the actual term from manual prehension, nobody before having used the word in such a sense, and he also used a number of new terms (for his doctrines were new). Well, a thing grasped by the senses he called itself a perception, and a perception so firmly grasped as to be irremovable by reasoning he termed knowledge, but a perception not so grasped he termed ignorance, and this was the source also of opinion, an unstable impression akin to falsehood and ignorance. But as a stage between knowledge and ignorance he placed that ‘grasp’ of which I have spoken.... On the strength of this he deemed the senses also trustworthy, because, as I said above, he held that a grasp achieved by the senses was both true and trustworthy, not because it grasped all the properties of the thing, but because it let go nothing that was capable of being its object, and because nature had bestowed as it were a 'measuring-rod' of knowledge and a first principle of itself from which subsequently notions of things could be impressed upon the mind, out of which not first principles only but certain broader roads to the discovery of reasoned truth were opened up. On the other hand error, rashness, ignorance, opinion, suspicion, and in a word all the things alien to firm and steady assent, Zeno set apart from virtue and wisdom. And it is on these points more or less that all Zeno’s departure and disagreement from the doctrine of his predecessors turned" (Academica I.40-42).

"...cognition (cognitio) or perception (perceptio) or (if we wish to give a literal translation) 'mental grasp (comprehensio),' the Stoic term κατάληψιν..." (Academica II.17).

"[A]cts of cognition (cognitiones) (which we may term comprehensions or perceptions (comprehensiones vel perceptiones), or, if these words are distasteful or obscure, καταλήψεις), — these we consider meet to be adopted for their own sake, because they possess an element that so to speak embraces and contains the truth" (On Ends III.17).

"Next follows the rest of the series linking on a chain of larger percepts, for instance the following, which embrace as it were a fully completed grasp of the objects: 'If it is a human being, it is a rational mortal animal.' From this class of percept are imprinted upon us our notions of things, without which all understanding and all investigation and discussion are impossible. But if false notions existed (I understood you to employ 'notions' to render (ἐννοίας)—well, if there were these false notions or notions imprinted on the mind by impressions of a kind that could not be distinguished from false ones, how pray could we act on them? how moreover could we see what is consistent with any given fact and what inconsistent" (Academica II.21-22)?

"What then is the probability that your school talk about? For if what a particular person happens to encounter, and almost at first glance thinks probable, is accepted as certain, what could be more frivolous than that? ... [W]hen they say that it can happen to the wise man that after he has taken every precaution and explored the position most carefully something may yet arise that while appearing to resemble truth is really very far remote from truth, they will be unable to trust themselves, even if they advance at all events a large part of the way, as they are in the habit of saying, towards the actual truth, or indeed come as near to it as possible. For to enable them to trust their judgement, it will be necessary for the characteristic mark of truth to be known to them, and if this be obscured and suppressed, what truth pray will they suppose that they attain to" (Academica II.36)?

"[L]et us say a few words on the subject of ‘assent’ or approval (termed in Greek συγκατάθεσιν)—not that it is not a wide topic, but the foundations have been laid a little time back. For while we were explaining the power residing in the senses, it was at the same time disclosed that many things are grasped and perceived by the senses, which cannot happen without the act of assent" (Academica II.37).

"[T]he mind must necessarily yield to clear impressions: since just as no animal can refrain from seeking to get a thing that is presented to its view as suited to its nature (the Greeks term it οἰκεῖον), so the mind cannot refrain from giving approval to a clear object when presented to it" (Academica II.38).

"Zeno used to demonstrate by gesture: for he would display his hand in front of one with the fingers stretched out and say 'An impression is like this'; next he closed his fingers a little and said, 'An act of assent is like this'; then he pressed his fingers closely together and made a fist, and said that that was comprehension [= cognition] (and from this illustration he gave to that process the actual name of κατάληψιν, which it had not had before); but then he used to apply his left hand to his right fist and squeeze it tightly and forcibly, and then say that such was knowledge, which was within the power of nobody save the wise man—but who is a wise man or ever has been even they themselves do not usually say" (Academica II.145).

• Impulsive impression
• Impulse
• Preconceptions
• Nature is provident

"...appetition (our chosen equivalent for the term ὁρμήν [= 'impulse']), by which we are impelled to action and seek to get an object of our impression,..." (Academica II.24).

"[T]he amount of craftsmanship that nature has employed in the construction first of every animal, then most of all in man,—the power possessed by the senses, the way in which we are first struck by the sense-presentations, next follows appetition [= impulse (ὁρμή)] imparted by their impact, and then we direct the senses to perceive the objects. For the mind itself, which is the source of the sensations and even is itself sensation, has a natural force which it directs to the things by which it is moved. Accordingly some sense-presentations it seizes on so as to make use of them at once, others it as it were stores away, these being the source of memory, while all the rest it unites into systems by their mutual resemblances, and from these are formed the concepts of objects which the Greeks term sometimes ἐννοίας and sometimes προλήψεις . When thereto there has been added reason and logical proof and an innumerable multitude of facts, then comes the clear perception of all these things, and also this same reason having been by these stages made complete finally attains to wisdom. Since therefore the mind of man is supremely well adapted for the knowledge of things and for consistency of life, it embraces information very readily, and your κατάληψιν, which as I said we will express by a literal translation as ‘grasp,’ is loved by the mind both for itself (for nothing is dearer to the mind than the light of truth) and also for the sake of its utility. Hence the mind employs the senses, and also creates the sciences as a second set of senses, and strengthens the structure of philosophy itself to the point where it may produce virtue, the sole source of the ordering of the whole of life" (Academica II.30-31).

"“It is the view of those whose system I adopt, that immediately upon birth (for that is the proper point to start from) a living creature feels an attachment for itself, and an impulse to preserve itself and to feel affection for its own constitution and for those things which tend to preserve that constitution; while on the other hand it conceives an antipathy to destruction and to those things which appear to threaten destruction. In proof of this opinion they urge that infants desire things conducive to their health and reject things that are the opposite before they have ever felt pleasure or pain; this would not be the case, unless they felt an affection for their own constitution and were afraid of destruction" (On Ends III.16).

"[T]he first appropriate act' (for so I render the Greek καθῆκον) is to preserve oneself in one's natural constitution; the next is to retain those things which are in accordance with nature and to repel those that are the contrary; then when this principle of choice and also of rejection has been discovered, there follows next in order choice conditioned by 'appropriate action'; then, such choice become a fixed habit; and finally, choice fully rationalized and in harmony with nature. It is at the right aim, this final stage that the Good properly so called first emerges and comes to be understood in its true nature. For originally man comes to be attached to those things which are in accordance with nature [= those things conducive to preserving itself]. But as soon as he has gained this understanding, or rather this notion which they call ennoia (ἔννοιαν), and he has come to see the order and, to put it this way, concord of the things to be done, he has come to value this concord so much more than all those things he had originally come to hold dear. And thus by insight and reasoning (cognitione et ratione) he has come to the conclusion that this highest good of men which is worthy of praise or admiration and desirable for its own sake lies precisely in this. It rests in what the Stoics call ὁμολογιαν, but which we may call agreement..." (On Ends III.20-21).

• Passions are a matter of false beliefs about what is good or bad

"Whereas the ancients claimed the passions (perturbationes) are natural and have nothing to do with reason, and whereas they located desire in one part of the soul, and reason in another, Zeno would not agree with that. He thought that these passions were equally voluntary and arose from a judgment which was a matter of mere opinion..." (Academica I.39).

"For as all disturbance is a movement of the soul either destitute of reason, or contemptuous of reason, or disobedient to reason, and as such a movement is provoked in two ways, either by an idea of good or idea of evil, we have four disturbances equally divided. For there are two proceeding from an idea of good, one of which is exuberant pleasure, that is to say, joy excited beyond measure by the idea of some great present good; the second is the intemperate longing for a supposed great good, and this longing is disobedient to reason, and may be rightly termed desire or lust. Therefore these two classes, exuberant pleasure and lust springing from the idea of good, disturb the soul just as the two remaining, fear and distress, cause disturbances by the idea of evil. For fear is the idea of a serious threatening evil and distress is the idea of a serious present evil and indeed an idea freshly conceived of an evil of such sort that it seems a due reason for anguish; now that means that the man who feels the pain believes that he ought to feel pain. We must, however, with all our might and main resist these disturbances which folly looses and launches like a kind of evil spirit upon the life of mankind, if we wish to pass our allotted span in peace and quiet" (Tusculan Disputations III.24).

"[W]e prefer to apply the term 'disorders (perturbationes)' ... to what the Greeks call πάθη.... This then is Zeno’s definition of disorder, which he terms πάθος, that it is an agitation of the soul alien from right reason and contrary to nature" (Tusculan Disputations IV.5.11-6.11). "There is the definition of disorder which I think Zeno rightly employed; for his definition is that 'disorder is an agitation of the soul alien from reason, contrary to nature,' or more briefly that 'disorder is a longing of undue violence,' unduly violent however being understood to mean a longing which is far removed from the equability of nature" (Tusculans Disputations IV.21.48).

"But all disorders are, they think, due to judgment and belief" (Tusculan Disputations IV.7.14). "But now that the cause of disorders is discovered, all of which originate in judgments based upon beliefs and upon consent of the will, let us at last put an end to this discussion" (Tusculan Disputations IV.38.82).

"But the man in whom there shall be perfect wisdom—we have never, it is true, seen a living example hitherto, but his character, if only one day he can be found, is described in the words of philosophers..." (Tusculan Disputations II.51).

"That only the wise man is free, and that every foolish man is a slave" (Ὅτι μόνος ὁ σοφὸς ἐλεύθερος καὶ πᾶς ἄφρων δοῦλος) (Stoic Paradoxes V).

"[I]t oftener happens that a mule brings forth a colt than that nature produces a sage" (On Divination II.61).

• Seneca. On Anger.

"'What then?' you say; 'when the wise man shall have something of this sort to deal with, will not his mind be affected by it, will it not be moved from its usual calm?' I admit that it will; it will experience some slight and superficial emotion. For as Zeno says: 'Even the wise man’s mind will keep its scar long after the wound has healed.' He will experience, therefore, certain suggestions and shadows of passion, but from passion itself he will be free" (On Anger I.16.7).

• Epictetus. Manual. Discourses.

• What is in our power
• The use of impressions
• What is free, not subject to restraint

"Of things some are in our power (ἐφ᾽ ἡμῖν), and others are not. In our power are opinion [= "taking up a position" (ὑπόληψις)], movement towards a thing (ὁρμή), desire, aversion (ἔκκλισις, turning from a thing); and in a word, whatever are our own acts: not in our power are the body, property, reputation, offices (magisterial power), and in a word, whatever are not our own acts. And the things in our power are by nature free (ἐλεύθερα), not subject to restraint nor hindrance..." (Manual 1).

"What then is your own? The use of impressions (χρῆσις φαντασιῶν)" (Manual 6). "If you have received the impression of any pleasure, guard yourself against being carried away by it; but let the thing wait for you, and allow yourself a certain delay on your own part" (Manual 34). "Remember that it is not he who reviles you or strikes you, who insults you, but it is your opinion (δόγμα) about these things as being insulting. When then a man irritates you, you must know that it is your own opinion which has irritated you. Therefore especially try not to be carried away by the impression. For if you once gain time and delay, you will more easily master yourself" (Manual 20). "But in the first place be not hurried away by the rapidity of the impression, but say, Impressions, wait for me a little: let me see who you are, and what you are about: let me put you to the test" (Discourses II.18). "For as Socrates said, we ought not to live a life without examination, so we ought not to accept an impression without examination, but we should say, Wait, let me see what you are and whence you come; like the watch at night (who says) Show me the pass. Have you the signal from nature which the appearance that may be accepted ought to have" (Discourses III.12)?

"In the first place then you must make your ruling faculty (ἡγεμονικόν) pure, and this mode of life also. Now (you should say), to me the matter to work on is my understanding, as wood is to the carpenter, as hides to the shoemaker; and my business is the right use of impressions (ὀρθὴ χρῆσις τῶν φαντασιῶν)" (Discourses III.22.)

"The material for the wise and good man is his own ruling faculty (ἡγεμονικόν).... The business of the wise and good man is to use appearances conformably to nature (χρῆσθαι ταῖς φαντασίαις κατὰ φύσιν): and as it is the nature of every soul to assent to the truth, to dissent from the false, and to remain in suspense as to that which is uncertain; so it is its nature to be moved by the desire of the good (τὸ ἀγαθὸν ὀρεκτικῶς κινεῖσθαι), and to aversion from the evil; and with respect to that which is neither good nor bad it feels indifferent. For as the money-changer (banker) is not allowed to reject Caesar's coin, nor the seller of herbs, but if you show the coin, whether he chooses or not, he must give up what is sold for the coin; so it is also in the matter of the soul. When the good appears, it immediately attracts to itself; the evil repels from itself. But the soul will never reject the manifest appearance of the good, any more than persons will reject Caesar's coin. On this principle depends every movement both of man and God" (Discourses III.3).

• The "will" (προαίρεσις) is free

"Disease is an impediment to the body, but not to the will (προαιρέσεως), unless the will itself chooses (θέλῃ). Lameness is an impediment to the leg, but not to the will" (Manual 9).

"Of all the faculties (except that which I shall soon mention), you will find not one which is capable of contemplating (θεωρητικήν) itself, and, consequently, not capable either of approving or disapproving. ... And what is this faculty [capable of contemplating itself]? The rational faculty (λογική); for this is the only faculty that we have received which examines itself, what it is, and what power it has, and what is the value of this gift, and examines all other faculties: for what else is there which tells us that golden things are beautiful, for they do not say so themselves? Evidently it is the faculty which is capable of judging of impressions (χρηστικὴ δύναμις ταῖς φαντασίαις). ... As then it was fit to be so, that which is best of all and supreme over all is the only thing which the gods have placed in our power (ἐφ᾽ ἡμῖν), the right use of impressions (τὴν χρῆσιν τὴν ὀρθὴν ταῖς φαντασίαις); but all other things they have not placed in our power. ... [T]his faculty of pursuing an object and avoiding it, and the faculty of desire and aversion, and, in a word, the faculty of using the impressions of things ( ὁρμητικήν τε καὶ ἀφορμητικὴν καὶ ὀρεκτικήν τε καὶ ἐκκλιτικὴν καὶ ἁπλῶς τὴν χρηστικὴν ταῖς φαντασίαις); and if you will take care of this faculty and consider it your only possession, you will never be hindered, (Discourses I.1).

"God had need of irrational animals to make use of appearances (χρωμένων ταῖς φαντασίαις), but of us to understand the use of appearances" (Discourses I.6).

"Hence Chrysippus rightly says: While consequences are uncertain (ἄδηλά), I will keep to those things which will bring me most in harmony with nature; for God himself hath formed me to choose (ἐκλεκτικόν) this. If I knew that it was inevitable for me to be sick, I would conform my inclinations that way; for even the foot, if it had understanding, would be inclined to get into the dirt" (Discourses II.6).

"[Y]ou have a will free by nature from hindrance and compulsion (προαίρεσιν ἔχεις ἀκώλυτον φύσει καὶ ἀνανάγκαστον).... I will show you this first in the matter of assent. Can any man hinder you from assenting to the truth? No man can. Can any man compel you to receive what is false? No man can. You see that in this matter you have the faculty of the will free from hindrance, free from compulsion, unimpeded. Well then, in the matter of desire and pursuit of an object, is it otherwise? And what can overcome pursuit except another pursuit? And what can overcome desire and aversion except another desire and aversion? But, you object: 'If you place before me the fear of death, you do compel me.' No, it is not what is placed before you that compels, but your opinion that it is better to do so and so than to die. In this matter then it is your opinion that compelled you: that is, will compelled will" (Discourses I.17).

"When then you would know how careless you are with respect to good and evil, and how active with respect to things which are indifferent, observe how you feel with respect to being deprived of the sight of the eyes, and how with respect to being deceived, and you will discover that you are far from feeling as you ought to do in relation to good and evil. But this is a matter which requires much preparation, and much labour and study. Well then do you expect to acquire the greatest of arts with small labour? And yet the chief doctrine of philosophers is very brief. If you would know, read Zeno's writings and you will see For how few words it requires to say that man's end (or object) is to follow the gods, and that the nature of good is a proper use of appearances (ὅτι τέλος ἐστὶ τὸ ἕπεσθαι θεοῖς, οὐσία δ᾽ ἀγαθοῦ χρῆσις οἵα δεῖ φαντασιῶν)" (Discourses I.20).

"But where there is will and the use of appearances (προαίρεσις καὶ χρῆσις τῶν φαντασιῶν), there you will see how many eyes he has so that you may say, Argus [= the "all-seeing" giant in Greek legend] was blind compared with him. Is his assent (συγκατάθεσις) ever hasty, his movement (ὁρμὴ) rash, does his desire ever fail in its object, does that which he would avoid befall him, is his purpose unaccomplished, does he ever find fault, is he ever humiliated, is he ever envious? To these he directs all his attention and energy; but as to every thing else he snores supine. All is peace; there is no robber who takes away his will (προαιρέσεως), no tyrant" (Discourses III.102.)

"[I]f we place the good in a right determination of the will (ὀρθῇ προαιρέσει), the very observance of the relations of life is good, and accordingly he who gives up any external things, obtains that which is good" (Discourses III.3).

• False beliefs about what is good or bad stand in the way of happiness

"Men are disturbed not by the things which happen, but by the opinions (δόγματα) about the things: for example, death is nothing terrible, for if it were, it would have seemed so to Socrates; for the opinion about death, that it is terrible, is the terrible thing. When then we are impeded or disturbed or grieved, let us never blame others, but ourselves, that is, our opinions" (Manual 5).

"When you see a person weeping in sorrow either when a child goes abroad or when he is dead, or when the man has lost his property, take care that the impression (φαντασία) do not hurry you away with it, as if he were suffering in external things. But straightway make a distinction in your own mind, and be in readiness to say, it is not that which has happened that afflicts this man, for it does not afflict another, but it is the opinion (δόγμα) about this thing which afflicts the man" (Manual 16).

"When any person treats you ill or speaks ill of you, remember that he does this or says this because he thinks that it is his duty (καθήκειν). It is not possible then for him to follow that which seems right to you, but that which seems right to himself. Accordingly if he is wrong in his opinion, he is the person who is hurt, for he is the person who has been deceived; for if a man shall suppose the true conjunction to be false, it is not the conjunction which is hindered, but the man who has been deceived about it. If you proceed then from these opinions, you will be mild in temper to him who reviles you: for say on each occasion, It seemed so to him (ἔδοξεν αὐτῷ)" (Manual 42).

"If what philosophers say is true, that all men have one principle (πᾶσιν ἀνθρώποις μία ἀρχὴ), as in the case of assent the persuasion that a thing is so, and in the case of dissent the persuasion that a thing is not so, and in the case of a suspense of judgment the persuasion that a thing is uncertain, so also in the case of a movement towards any thing the persuasion that a thing is for a man's advantage, and it is impossible to think that one thing is advantageous and to desire another, and to judge one thing to be proper and to move towards another, why then are we angry with the many? They are thieves and robbers, you may say. What do you mean by thieves and robbers? They are mistaken about good and evil. Ought we then to be angry with them, or to pity them? But show them their error, and you will see how they desist from their errors. If they do not see their errors, they have nothing superior to their present opinion (δοκοῦντος)" (Discourses I.18).

"We ought then to eradicate these bad opinions (δόγματα), and to this end we should direct all our efforts. For what is weeping and lamenting? Opinion. What is bad fortune? Opinion. What is civil sedition, what is divided opinion, what is blame, what is accusation, what is impiety, what is trifling?. All these things are opinions, and nothing more, and opinions about things independent of the will, as if they were good and bad (ἀγαθῶν καὶ κακῶν)" (Discourses III.3).

• Preconceptions, rash assent, false belief

"Preconceptions (προλήψεις) are common to all men, nor does one such principle contradict another; for which of us does not admit that good is advantageous and eligible, and in all cases to be pursued and followed? Who does not admit that justice is fair and becoming? Where, then, arises the dispute? In adapting these preconceptions to particular cases; as when one cries, 'Such a person has acted well,-he is a gallant man;' and another, 'No, he has acted like a fool.' Hence arise disputes among men. ... What, then, is it to be properly educated? To learn how to apply the preconceptions to particular cases, and, for the rest, to distinguish that some things are in our power (ἐφ᾽ ἡμῖν), while others are not. In our own power are the will (προαίρεσις), and all purposeful actions; out of our power, the body and its parts, property, parents, brothers, children, country, and, in short, all our fellow-beings. Where, then, shall we place good? In what shall we define it to consist? In things within our own power" (Discourses I.22).

Socrates didn't write? Who has written as much as he? But how? Because, since he couldn't always have someone to test his judgements or to be tested by him in turn, he made a habit of testing and examining himself, and was for ever trying out the use of some particular preconception (πρόληψιν). That is how a philosopher writes" (Discourses II.1).

"[T]o learn what Socrates taught, what is the nature of each thing that exists, and that a man should not rashly adapt preconceptions (προλήψεις) to the several things which are. For this is the cause to men of all their evils, the not being able to adapt the general preconceptions to the several things. But we have different opinions. One man thinks that he is sick: not so however, but the fact is that he does not adapt his preconceptions right. Another thinks that he is poor; another that he has a severe father or mother; and another again that Caesar is not favourable to him. But all this is one and only one thing, the not knowing how to adapt the preconceptions. For who has not a preconception of that which is bad, that it is hurtful, that it ought to be avoided, that it ought in every way to be guarded against? One preconception is not repugnant to another, only where it comes to the matter of adaptation" (Discourses IV.1).

• Galen. On the Doctrines of Hippocrates and Plato.

• Against Chrysippus' explanation of the origin of vice

"[Chrysippus contradicts himself] in his account of the definition of passion (πάθος), when he says that passion is an irrational and unnatural movement of the soul and an excessive impulse (πλεονάζουσαν ὁρμήν).... These are both in conflict with his statement that passions are judgments (κρίσεις εἶναι τὰ πάθη)" (On the Doctrines of Hippocrates and Plato IV.2.8-9).

"[I]t is not surprising that he [Chrysippus] was perplexed about the origin of vice (άπορεῖ περὶ τῆς κατὰ τὴν κακίαν γενέσεως). He could not state its cause (αίτίαν) or the ways in which it comes to exist; and he could not discover how it is that children err. On all these points it was reasonable, I think, for Posidonius to censure and refute him. For if from the start children felt a kinship with excellence (τὸ καλὸν), their misconduct could not arise internally or from themselves, but necessarily come to them only from the outside. But even though they are brought up in good habits and are give the education that they ought to have, yet they are invariably observed doing something wrong; and Chrysippus acknowledges this fact. ... [H]e granted that even if children were raised under the exclusive care of a philosopher and never saw or heard any example of vice, nevertheless they would not necessarily become philosophers. There are two causes (he says) of their corruption; one arises in them from the conversation of the majority of men, the other from the very nature of things (ἐξ αὐτῆς τῶν πραγμάτων τῆς φύσεως). I have objections to both of these causes, beginning with that arises from associations. It occurs to me to wonder why it is that when they have seen and heard an example of vice, they do not hate it and flee from it, since they no kinship with it; and I wonder all the more that they should be corrupted when they neither seen nor hear such examples and are deceived by the very things themselves. What necessity it there that children be enticed by pleasure as a good thing, when they feel no kinship with it, or that they avoid and flee from pain if they are not by nature also alienated from it? ... [W]hen he says that corruption arises in inferior men in regard to good and evil because of the persuasiveness of impressions (πιθανότητα τῶν φαντασιῶν) and the talk of me, we must ask him why it is that pleasure projects the persuasive impression that it is good, and pain that it is evil" (On the Doctrines of Hippocrates and Plato V.5.9-20).

("When a rational (λογικὸν) being is perverted, this is due to the deceptiveness of external pursuits (πραγματειῶν πιθανότητας) or sometimes to the influence of associates. For the starting-points of nature are never perverse" (Diogenes Laertius, Lives of the Philosophers VII.1.89).)

• Sextus Empiricus. Against the Logicians. Against the Ethicists. Outlines of Pyrrhonism.

• Cognitive impression, cognition, knowledge, opinion

"[The Stoics] assert that there are three criteria—knowledge (ἐπιστήμην) and opinion (δόξαν) and, set midway between these two, apprehension [= cognition (κατάληψιν)]; and of these knowledge is the unerring and firm apprehension which is unalterable by reason, and opinion is weak and false assent, and apprehension is intermediate between these, being assent to an apprehensive presentation [= cognitive impression (καταληπτικῆς φαντασίας)]; and an apprehensive presentation, according to them, is one which is true and of such a kind as to be incapable of becoming false. And they say that, of these, knowledge subsists only in the wise, and opinion only in the fools, but apprehension is shared alike by both, and it is the criterion of truth" (Against the Logicians I.151-153).

"These men, then, assert that the criterion of truth is the cognitive impression (καταληπτικὴν φαντασίαν)" (Against the Logicians I.227).

"[A cognitive impression] being plainly evident (ἐναργὴς) and striking, lays hold of us, almost by the very hair, as they say, and drags us off to assent (συγκατάθεσιν), needing nothing else to help it to be thus impressive or to suggest its superiority over all others. For this reason, too, every man, when he is anxious to apprehend (καταλαμβάνεσθαι) any object exactly, appears of himself to pursue after an impression of this kind—as, for instance, in the case of visible things, when he receives a dim impression of the real object. For he intensifies his gaze and draws close to the object of sight so as not to go wholly astray, and rubs his eyes and in general uses every means until he can receive a clear and striking impression of the thing under inspection, as though he considered that the credibility of the apprehension (τὴν τῆς καταλήψεως πίστιν) depended upon that" (Against the Logicians I.257-258).

"[I]f every conception of the fool is, according to them, ignorance and only the Sage speaks the truth and possesses firm knowledge of the true, it follows that, since up till now the Sage has proved undiscoverable, the true also is necessarily undiscoverable; and because of this, all things are non-apprehensible, seeing that we all, being fools, do not possess a firm apprehension of existent things" (Against the Logicians I.432-433).

"[A]ccording to the Stoics the cognitive impression (καταληπτικὴ φαντασία) is judged to be cognitive by the fact that it proceeds from an existing object and in such a way as to bear the impress and stamp of that existing object; and the existing object is approved as existent because of its exciting a cognitive impression" (Sextus Empiricus, Against the Ethicists 183).

• Aëtius in Placita Philosophorum, Pseudo-Plutarch.

• Preconception, conception, reason

"When a man is born, the Stoics say, he has the commanding-part of his soul (τὸ ἡγεμονικὸν μέρος τῆς ψυχῆς) like a sheet of paper ready for writing upon. On this he inscribes each of his conceptions (ἐννοιῶν). The first method of inscription is through the senses. For by perceiving something, e.g., white, they have a memory of it when it has departed. And when many memories of a similar kind have occurred, we then say we have experience (ἐμπειρίαν). For the plurality of similar impressions is experience. Some conceptions arise naturally in the aforesaid ways and undesignatedly, others through our own instruction and attention. The later are called 'conceptions (ἔννοιαι)' only, the former are called 'preconceptions (προλήψεων)' as well. Reason (λόγος), for which we are called rational (λογικοί), is said to be completed from our preconceptions (προλήψεων) during our first seven years" (Pseudo-Plutarch, Placita 4.11).

(By concept I mean what the Greeks call now ἔννοια, now πρόληψις. This is an innate knowledge of anything, which has been previously apprehended, and needs to be unfolded (Ea est insita et ante percepta cuiusque cognitio enodationis indigens)" (Cicero, Topica VII.1.31).)

• Arius Didymus in Anthology, Stobaeus.

• Impulsive impressions

"What sets impulse in motion, they [the Stoics] say is nothing other than an impression capable of directly impelling an appropriate act (τὸ δὲ κινοῦν τὴν ὁρμὴν οὐδὲν λέγουσιν ἀλλ' ἢ φαντασίαν ὁρμητικὴν τοῦ καθήκοντος αὐτόθεν)" (2.86.17-18). "They [the Stoics] say that all impulses are acts of assent, and [although there are other kinds of assent,] the practical ones also contain motive power (πάσας δε τας όρμάς συγκαταθέσεις είναι, τὰς δε πρακτικάς και το κινητικόν περιέχειν). Acts of assent and impulses differ in their objects: propositions are the objects of acts of assent, but impulses are directed toward predicates contained somehow in (ἐπὶ κατηγορήματα τα περιεχόμενά πως ἐν) the propositions" (2.88.2-6).

• Diogenes Laertius. Life of Zeno.

• Impression
• Cognitive impression, preconception
• Cognition, knowledge
• Rational impressions, non-rational impressions

"Now the part which deals with canons or criteria (κανόνων καὶ κριτηρίων) they admit as a means for the discovery of truth, since in the course of it they explain the different kinds of impressions (φαντασιῶν) that we have. And similarly the part about definitions is accepted as a means of recognizing truth, inasmuch as things are apprehended (λαμβάνεται) by means of general notions (ἐννοιῶν)" (Lives of the Philosophers VII.1.42).

"An impression (φαντασίαν) is an imprint on the soul: the name having been appropriately borrowed from the imprint made by the seal upon the wax. Of impressions, some are cognitive (καταληπτικήν) and some are not-cognitive (ἀκατάληπτον). The former, which they say is the criterion (κριτήριον) of reality, is defined as that which proceeds from a real object, agrees with that object itself, and has been imprinted seal-fashion and stamped upon the mind: the latter, or non-cognitive, that which does not proceed from any real object, or, if it does, fails to agree with the reality itself, not being clear or distinct (μὴ τρανῆ μηδὲ ἔκτυπον)" (Lives of the Philosophers VII.1.45-46).

"Irrefutability is strength in argument so as not to be brought over by it to the opposite side. Earnestness is a habit of referring impressions (φαντασίας) to right reason (ὀρθὸν λόγον). Knowledge (ἐπιστήμην) itself they define either as secure cognition (κατάληψιν) or as a habit or state which in reception of impressions cannot be shaken by argument. Without the study of dialectic (διαλεκτικῆς), they say, the wise man cannot guard himself in argument so as never to fall; for it enables him to distinguish between truth and falsehood, and to discriminate what is merely plausible and what is ambiguously expressed, and without it he cannot methodically put questions and give answers" (Lives of the Philosophers VII.1.47).

"The Stoics agree to put in the forefront the doctrine of impression and sense-perception (φαντασίας καὶ αἰσθήσεως), inasmuch as the criterion (κριτήριον) by which the truth of things is tested is generically an impression, and again the theory of assent (συγκαταθέσεως) and that of cognition (καταλήψεως) and thought (νοήσεως), which precedes all the rest, cannot be stated apart from impression. For impression comes first; then thought, which is capable of expressing itself, puts into the form of a proposition that which the subject receives from an impression" (Lives of the Philosophers VII.1.49).

"Another division of impressions (φαντασιῶν) is into rational (λογικαί) and irrational (ἄλογοι), the former being those of rational creatures, the latter those of the irrational. Those which are rational are processes of thought (νοήσεις), while those which are irrational have no name" (Lives of the Philosophers VII.1.51).

"The criterion of truth (Κριτήριον δὲ τῆς ἀληθείας) they declare to be the cognitive impression (καταληπτικὴν φαντασίαν), i.e. that which comes from a real object--according to Chrysippus in the twelfth book of his Physics.... In the first book of his Exposition of Doctrine, he contradicts himself and declares that sensation and preconception (αἴσθησιν καὶ πρόληψιν) are the only standards, preconception being a general notion which comes by the gift of nature (ἔστι δ᾽ ἡ πρόληψις ἔννοια φυσικὴ τῶν καθόλου)" (Lives of the Philosophers VII.1.54).

"A notion or object of thought is an impression to the intellect (Ἐννόημα δέ ἐστι φάντασμα διανοίας)..." (Lives of the Philosophers VII.1.61).

• Impulse
• Use of impressions, origin of vice, passion
• Providence in nature
• Wisdom
• Virtue and vice

"An animal's first impulse (ὁρμήν), say the Stoics, is to self-preservation, because nature from the outset endears it to itself, as Chrysippus affirms in the first book of his work On Ends....[N]ature in constituting the animal made it near and dear to itself; for so it comes to repel all that is injurious and give free access to all that is serviceable or akin to it" (Lives of the Philosophers VII.1.85).

"And nature, they say, made no difference originally between plants and animals, for she regulates the life of plants too, in their case without impulse and sensation (ὁρμῆς καὶ αἰσθήσεως), just as also certain processes go on of a vegetative kind in us. But when in the case of animals impulse has been superadded, whereby they are enabled to go in quest of their proper aliment, for them, say the Stoics, Nature's rule is to follow the direction of impulse. But when reason (λόγου) by way of a more perfect leadership has been bestowed on the beings we call rational (λογικοῖς), for them life according to reason rightly becomes the natural life (τὸ κατὰ λόγον ζῆν ὀρθῶς γίνεσθαι <τού> τοις κατὰ φύσιν). For reason supervenes to shape impulse scientifically (τεχνίτης γὰρ οὗτος ἐπιγίνεται τῆς ὁρμῆς). This is why Zeno was the first (in his treatise On the Nature of Man) to designate as the end 'life in agreement (ὁμολογουμένως) with nature' (or living agreeably to nature), which is the same as a virtuous life, virtue being the goal towards which nature guides us. ... And this is why the end may be defined as life in accordance with nature, or, in other words, in accordance with our own human nature as well as that of the universe, a life in which we refrain from every action forbidden by the law common to all things, that is to say, the right reason which pervades all things, and is identical with this Zeus, lord and ruler of all that is. And this very thing constitutes the virtue of the happy man and the smooth current of life, when all actions promote the harmony of the spirit dwelling in the individual man with the will of him who orders the universe" (Lives of the Philosophers VII.1.86-88).

"They hold that there are two principles in the universe, the active principle and the passive. The passive principle, then, is a substance without quality, i.e. matter, whereas the active is the reason (λόγον) inherent in this substance, that is God. For he is everlasting and is the artificer of each several thing throughout the whole extent of matter" (Lives of the Philosophers VII.134).

"God is one and the same with Mind, Fate, and Zeus (νοῦν καὶ εἱμαρμένην καὶ Δία); he is also called by many other names" (Lives of the Philosophers VII.135).

("Chrysippus..., musters an enormous mob of unknown gods.... He says that the divine power resides in reason, and the soul and mind of the universe; the the world itself a god, and also the all-pervading world-soul, and again the guiding principle of that soul, which operates in the intellect and reason, and the common and all-embracing nature of things; and also the power of fate, and the necessity that governs future events; besides this, [many other things]" (Cicero, On the Nature of the Gods, I.39).)

"The notions of justice and goodness come by nature (φυσικῶς δὲ νοεῖται δίκαιόν τι καὶ ἀγαθόν)" (Lives of the Philosophers VII.53).

"[A] definition of good which they give is 'the natural perfection of a rational being qua rational (τὸ τέλειον κατὰ φύσιν λογικοῦ ὡς λογικοῦ).' To this answers virtue and, as being partakers in virtue, virtuous acts and good men ; as also its supervening accessories, joy and gladness and the like" (Lives of the Philosophers VII.94).

"Overhastiness in assertion affects the actual course of events, so that, unless we are well trained in handling impressions (φαντασίας), we are liable to fall into unseemly conduct and heedlessness" (Lives of the Philosophers VII.1.48).

"Passion (πάθος) is defined by Zeno as an irrational and unnatural movement in the soul (ἄλογος καὶ παρὰ φύσιν ψυχῆς κίνησις), or again as impulse in excess (ὁρμὴ πλεονάζουσα)" (Lives of the Philosophers VII.1.110).

"They hold the emotions (πάθη) to be judgements (κρίσεις), as is stated by Chrysippus in his treatise On the Passions..." (Lives of the Philosophers VII.1.111).

"[T]hey [the Stoics] say "that the wise man is free from passion (ἀπαθῆ)..." (Lives of the Philosophers VII.1.117).

"[T]hey say that the wise man will never form opinions (δοξάσειν), that is to say, he will never give assent to anything that is false. ... [And] they declare that he alone is free (ἐλεύθερον)..." (Lives of the Philosophers VII.1.121).

"It is a tenet of theirs that between virtue and vice (ἀρετῆς καὶ κακίας) there is nothing intermediate..." (Lives of the Philosophers VII.1.127).

The Academic Skeptics

Academic Skepticism begins in 265 BC with Arcesilaus, who succeeded Crates as the sixth head of the Academy Plato founded almost a hundred years ago in 387 BC. Arcesilaus refocused the Academy by interpreting Plato's dialogues in terms of the Socratic practice of exposing the pretense to wisdom. There were disputes about how to understand this skepticism.

Most of what is known about Academic Skepticism depends on the discussion in Cicero's Academica.

• Cicero. Academica.

"It was entirely with Zeno, so we have been told, that Arcesilas set on foot his battle, not from obstinacy or desire for victory, as it seems to me at all events, but because of the obscurity of the facts that had led Socrates to a confession of ignorance.... Accordingly Arcesilas said that there is nothing that can be known, not even that residuum of knowledge that Socrates had left himself—the truth of this very dictum: so hidden in obscurity did he believe that everything lies, nor is there anything that can be perceived or understood, and for these reasons, he said, no one must make any positive statement or affirmation or give the approval of his assent to any proposition, and a man must always restrain his rashness and hold it back from every slip, as it would be glaring rashness to give assent either to a falsehood or to something not certainly known, and nothing is more disgraceful than for assent and approval to outstrip knowledge and perception. His practice was consistent with this theory—he led most of his hearers to accept it by arguing against the opinions of all men, so that when equally weighty reasons were found on opposite sides on the same subject, it was easier to withhold assent from either side. They call this school the New Academy..." (Academica I.45-46).

"[T]he sole object of our discussions is by arguing on both sides to draw out and give shape to some result that may be either true or the nearest possible approximation to the truth. Nor is there any difference between ourselves and those who think that they have positive knowledge except that they have no doubt that their tenets are true, whereas we hold many doctrines as probable, which we can easily act upon but can scarcely advance as certain..." (Academica II.7-8).

"[Philo had] maintained that there was nothing that could be grasped (that is the expression that we choose in rendering ἀκατάληπτον), if that ‘presentation’ of which he spoke (for we have by this time sufficiently habituated ourselves by our yesterday’s conversation to this rendering of φαντασίᾳ) was, as Zeno defined it, a presentation impressed and moulded from the object from which it came in a form such as it could not have if it came from an object that was not the one that it actually did come from (we declare that this definition of Zeno’s is absolutely correct, for how can anything be grasped in such a way as to make you absolutely confident that it has been perceived and known, if it has a form that could belong to it even if it were false?)—but when Philo weakens and abolishes this, he abolishes the criterion between the unknowable and the knowable; which leads to the inference that nothing can be grasped..." (Academica II.18).

"For they [= the Academic Skeptics] hold (and this in fact, I noticed, excites your school extremely) that something is 'probable (probabile),' or as it were resembling the truth (veri simile), and that this provides them with a canon of judgement both in the conduct of life and in philosophical investigation and discussion" (Academica II.32).

"if you bring forward 'probable presentation' [= plausible impression (φαντασία πιθανὴ)], or 'probable and unhampered presentation' [= plausible and unhampered impression (φαντασία πιθανὴ καὶ ἀπερίσπαστος)], as Carneades held, or something else, as a guide for you to follow..." (Academica II.33-34).

"[The] argument [against the Stoics] is constructed as follows: 'Some impressions are true, others false; and what is false cannot be perceived (percipi). But a true impression is invariably of such a sort that a false impression also could be of exactly the same sort; and among impressions of such a sort that there is no difference between them, it cannot occur that some are capable of being perceived and others are not. Therefore there is no impression that is capable of being perceived" (Academica II.40-41).

"[T]he way in which they [the Academic Skeptics] harp on cases of resemblance between twins or between the seals stamped by signet-rings is childish. For which of us denies that resemblances exist, since they are manifest in ever so many things? But if the fact that many things are like many other things is enough to do away with knowledge (cognitionem), why are you not content with that, especially as we admit it, and why do you prefer to urge a contention utterly excluded by the nature of things.... For it is granted that two twins are alike, and that might have satisfied you; but you want them to be not alike but downright identical, which is absolutely impossible" (Academica II.54-55).

"These considerations necessarily engendered the doctrine of ἐποχή, that is, ‘a holding back of assent,’ in which Arcesilas was more consistent, if the opinions that some people hold about Carneades are true. For if nothing that has presented itself to either of them can be perceived, assent must be withheld; for what is so futile as to approve anything that is not known? But we kept being told yesterday that Carneades was also in the habit of taking refuge in the assertion that the wise man will occasionally hold an opinion, that is, commit an error" (Academica II.59).

"For how can I fail to be eager for the discovery of truth, when I rejoice if I have discovered something that resembles truth? But just as I deem it supremely honourable to hold true views, so it is supremely disgraceful to approve falsehoods as true. And nevertheless I myself am not the sort of person never to give approval to anything false, never give absolute assent, never hold an opinion; it is the wise man that we are investigating. For my own part however, although I am a great opinion-holder (for I am not a wise man)..." (Academica II.66).

"'If the wise man ever assents to anything, he will sometimes also form an opinion; but he never will form an opinion; therefore he will not assent to anything.' This syllogism Arcesilas used to approve, for he used to accept both the major premiss and the minor (Carneades used sometimes to grant as minor premiss that the wise man sometimes assents, so that it followed that he also holds an opinion..." (Academica II.67).

"We may suppose Arcesilaus putting the question to Zeno, what would happen if the wise man was unable to perceive anything [= have a cognitive impression] and also it was the mark of the wise man not to form an opinion. Zeno no doubt replied that the wise man's reason for abstaining from forming an opinion would be that there was something that could be perceived. What then was this, asked Arcesilaus. An impression, was doubtless the answer. Then what sort of impression? Hereupon no doubt Zeno defined it as follows, an impression impressed and sealed and moulded from a real object, in conformity with its reality. There followed the further question, did this hold good even if a true impression was of exactly the same form as a false one? At this I imagine Zeno was sharp enough to see that if an impression proceeding from a non-existent thing could be of the same form, there was no impression that could be perceived. Arcesilas agreed that this addition to the definition was correct, for it was impossible to perceive either a false presentation or a true one if a true one had such a character as even a false one might have; but he pressed the points at issue further in order to show that no presentation proceeding from a true object is such that a presentation proceeding from a false one might not also be of the same form. This is the one argument that has held the field down to the present day. For the point that the wise man will not assent to anything, had no essential bearing on this dispute; for he might perceive nothing and yet form an opinion—a view which is said to have been accepted by Carneades; although for my own part, trusting Clitomachus more than Philo or Metrodorus, I believe that Carneades did not so much accept this view as advance it in argument [against the Stoics]" (Academica II.77-78).

"If a person looking at Publius Servilius Geminus used to think he saw [his twin] Quintus he was encountering an impression of a sort that could not be perceived, because there was no mark to distinguish a true impression from a false one; and if that mode of distinguishing were removed, what mark would he have, of such a sort that it could not be false, to help him to recognize Gaius Cotta, who was twice consul with Geminus? You say that so great a degree of resemblance does not exist in the world. You show fight, no doubt, but you have an easy-going opponent; let us grant by all means that it does not exist, but undoubtedly it can appear to exist, and therefore it will cheat the sense, and if a single case of resemblance has done that, it will have made everything doubtful; for when that proper canon of recognition has been removed, even if the man himself who you see is the man he appears to you to be, nevertheless you will not make that judgement, as you it it ought to be made, by means of a mark of such a sort that a false likeness could not have the same character" (Academica II.84).

"I shall take it from Clitomachus, who was a companion of Carneades quite until old age, a clever fellow as being a Carthaginian, and also extremely studious and industrious. There are four volumes of his that deal with the withholding of assent, but what I am now going to say has been taken from Volume One. Carneades holds that there are two classifications of presentations [= impressions (φαντασίαι)], which under one are divided into those that can be perceived [= those impressions to which assent is cognition (κατάληψις)] and those that cannot, and under the other into those that are probable (probabilia) and those that are not probable; and that accordingly those presentations that are styled by the Academy contrary to the senses and contrary to perspicuity belong to the former division, whereas the latter division must not be impugned; and that consequently his view is that there is no presentation of such a sort as to result in perception, but many that result in a judgement of probability. For it is contrary to nature for nothing to be probable, and entails that entire subversion of life of which you, Lucullus, were speaking; accordingly even many sense-percepts must be deemed probable, if only it be held in mind that no sense-presentation has such a character as a false presentation could not also have without differing from it at all. Thus the wise man will make use of whatever apparently probable presentation he encounters, if nothing presents itself that is contrary to that probability, and his whole plan of life will be charted out in this manner. In fact even the person whom your school brings on the stage as the wise man follows many things probable, that he has not grasped nor perceived nor assented to but that possess verisimilitude; and if he were not to approve them, all life would be done away with" (Academica II.99-100).

"After setting out these points, he [Clitomachus] adds that the formula 'the wise man withholds assent' is used in two ways, one when the meaning is that he gives absolute assent to no impression at all (omnino eum rei nulli adsentiri), the other when he restrains himself from replying so as to convey approval or disapproval of something, with the consequence that he neither makes a negation nor an affirmation; and that this being so, he holds the one plan in theory, so that he never assents, but the other in practice, so that he is guided by probability (probabilitatem), and wherever this confronts him or is wanting he can answer 'yes' or 'no' accordingly. In fact as we hold that he who restrains himself from assent about all things nevertheless does move and does act, the view is that there remain impressions of a sort that arouse us to action, and also answers that we can give in the affirmative or the negative in reply to questions, merely following a corresponding impression, provided that we answer without actual assent; but that nevertheless not all impressions of this character were actually approved, but those that nothing hindered" (Academica II.104).

"... especially as he [the Academic Skeptic] is able to follow mere resemblance to truth when unhampered, without the act of assent (Academica II.107-108)?

"Clitomachus used to declare that he had never been able to understand what Carneades did accept..." (Academica II.139).

"'My view [= Philo's view before his Roman Books]?' replied Catulus, 'I am coming round to the view of my father, which indeed he used to say was that of Carneades, and am beginning to think that nothing can be perceived [= nothing can be cognized], but to deem that the wise man will assent to something not perceived, that is, will hold an opinion, but with the qualification that he will understand (intellegat) that it is an opinion and will know (sciatque) that there is nothing that can be comprehended and perceived; and therefore although [in this way] agreeing with their rule of ἐποχήν [= holding back] as to everything, I assent emphatically to that second view, that nothing exists that can be perceived.'
'I have your view,' said I, 'and I do not think it quite negligible; but pray, Hortensius, what do you think?'
'Away with it [= away with assent and away with us]!' he replied with a laugh.
'I take you,' said I, 'for that is the true Academic verdict.'
The conversation thus concluded, Catulus stayed behind, while we went down to our boats" (Academica II.148).

• Sextus Empiricus. Against the Logicians. Outlines of Pyrrhonism.

"[The Stoics] assert that there are three criteria—knowledge (ἐπιστήμην) and opinion (δόξαν) and, set midway between these two, cognition (κατάληψιν); and of these knowledge is the unerring and firm apprehension which is unalterable by reason, and opinion is weak and false assent, and cognition is intermediate between these, being assent to a cognitive presentation; and a cognitive presentation, according to them, is one which is true and of such a kind as to be incapable of becoming false. And they say that, of these, knowledge subsists only in the wise, and opinion only in the fools, but cognition is shared alike by both, and it is the criterion of truth. It was these statements of the Stoics that Arcesilaus controverted by proving that cognition is not a criterion intermediate between knowledge and opinion" (Against the Logicians I.150-153).

"[Carneades] too, himself requires a criterion for the conduct of life and for the attainment of happiness, he is practically compelled on his own account to frame a theory about it, and to adopt both the plausible impression (πιθανὴν φαντασίαν) and that which is at once plausible and irreversible and tested" (Against the Logicians I.166-167).

"[T]hat which appears true, and appears so vividly (ἱκανῶς ἐμφαινομένη), is the criterion of truth according to the School of Carneades. And, being the criterion, it has a large extension, and when extended one impression reveals itself as more plausible and more vivid (πιθανωτέραν τε καὶ πληκτικωτέραν) than another. ... Hence the criterion will be the apparently true impression, which the Academics called 'plausible (πιθανὴν)'" (Against the Logicians I.171-175).

"For we believe that this man is Socrates from the fact that he possesses all his customary qualities—colour, size, shape, converse, coat, and his position in a place where there is no one exactly like him. And just as some doctors do not deduce that it is a true case of fever from one symptom only—such as too quick a pulse or a very high temperature—but from a concurrence, such as that of a high temperature with a rapid pulse and soreness to the touch and flushing and thirst and analogous symptoms; so also the Academic forms his judgement of truth by the concurrence of presentations, and when none of the presentations in the concurrence provokes in him a suspicion of its falsity he asserts that the impression is true. And that the 'irreversible' presentation is a concurrence capable of implanting belief is plain from the case of Menelaus; for when he had left behind him on the ship the wraith of Helen—which he had brought with him from Troy, thinking it to be the true Helen—and had landed on the island of Pharos, he beheld the true Helen, but though he received from her a true presentation, yet he did not believe that presentation owing to his mind being warped by that other impression from which he derived the knowledge that he had left Helen behind in the ship. Such then is the 'irreversible' presentation; and it too seems to possess extension inasmuch as one is found to be more irreversible than another. Still more trustworthy than the irreversible presentation and supremely perfect is that which creates judgement; for it, in addition to being irreversible, is also 'tested.' What the distinctive feature of this presentation is we must next explain. Now in the case of the irreversible presentation it is merely required that none of the presentations in the concurrence should disturb us by a suspicion of its falsity but all should be apparently true and not improbable; but in the case of the concurrence which involves the 'tested' presentation, we scrutinize attentively each of the presentations in the concurrence..." (Against the Logicians I.178-182).

"For all these factors together form the criterion—namely, the probable presentation, and that which is at once both probable and irreversible and besides these that which is at once probable and irreversible and tested. And it is because of this that, just as in ordinary life when we are investigating a small matter we question a single witness, but in a greater matter several, and when the matter investigated is still more important we cross-question each of the witnesses on the testimony of the others,—so likewise, says Carneades, in trivial matters we employ as criterion only the probable presentation, but in greater matters the irreversible, and in matters which contribute to happiness the tested presentation. Moreover, just as they adopt, they say, a different presentation to suit different cases, so also in different circumstances they do not cling to the same presentation. For they declare that they attend to the immediately probable in cases where the circumstances do not afford time for an accurate consideration of the matter. A man, for example, is being pursued by enemies, and coming to a ditch he receives a presentation which suggests that there, too, enemies are lying in wait for him; then being carried away by this presentation, as a probability, he turns aside and avoids the ditch, being led by the probability of the presentation, before he has exactly ascertained whether or not there really is an ambush of the enemy at the spot. But they follow the probable and tested presentation in cases where time is afforded for using their judgement on the object presented with deliberation and thorough examination. For example, on seeing a coil of rope in an unlighted room a man jumps over it, conceiving it for the moment to be a snake, but turning back afterwards he inquires into the truth, and on finding it motionless he is already inclined to think that it is not a snake, but as he reckons, all the same, that snakes too are motionless at times when numbed by winter’s frost, he prods at the coiled mass with a stick, and then, after thus testing the presentation received, he assents to the fact that it is false to suppose that the body presented to him is a snake" (Against the Logicians I.184-188).

"...the Stoics approving the 'cognitive' impressions, and the Academics those which appear to be 'plausible.' But, on examining it closely, this view also seems to us more like a pious aspiration than the truth. For a 'cognitive' impression—to take this first—is one which is 'imprinted and impressed by a real object and in accordance with that object itself, and such as could not be produced by anything not real.' As to the rest of this account Carneades says that he will concede it to the Stoics, but the clause “Such as could not be produced by what is not real' should not be conceded. For impressions are produced by non-real objects just as by real ones. And the fact that they are found equally self-evident and striking is a token of their indistinguishability, while the fact that corresponding actions are linked to them is a token of their being equally striking and self-evident" (Against the Logicians I.401-403).

"If, then, presentations are cognitive in so far as they attract us to assent and to the following of them up with corresponding action, then, since false ones also are seen to be of this kind, we must declare that the non-cognitive presentations are indistinguishable from the cognitive" (Against the Logicians I.405).

"They summon the Stoics to face apparent facts. For in the case of things similar in shape but differing in substance it is impossible to distinguish the apprehensive presentation from the false and non-apprehensive. If, for example, of two eggs that are exactly alike I offer each one in turn to the Stoic for him to distinguish between them, will the Sage be able on inspection to declare indubitably whether the egg exhibited is this one or that other one? And the same argument also holds good in the case of twins" (Against the Logicians I.408-410).

"Philo asserts that objects are inapprehensible (ἀκατάληπτα) so far as concerns the Stoic criterion, that is to say 'cognitive impression (καταληπτικῇ φαντασίᾳ),' but are apprehensible so far as concerns the real nature of the objects themselves (ἐπὶ τῇ φύσει τῶν πραγμάτων αὐτῶν καταληπτά)" (Sextus Empiricus, Outlines of Pyrrhonism I.33).

• Diogenes Laertius. Lives of the Philosophers.

"Arcesilaus... was the first to suspend his judgement owing to the contradictions of opposing arguments. He was also the first to argue on both sides of a question, and the first to meddle with the system handed down by Plato..." (Lives of the Philosophers IV.6.28).

"Carneades... studied carefully the writings of the Stoics and particularly those of Chrysippus, and by combating these successfully he became so famous..." (Lives of the Philosophers IV.9.62).

"[Carneades] had many other disciples, but the most illustrious of them all was Clitomachus.... He succeeded Carneades in the headship of the school, and by his writings did much to elucidate his opinions" (Lives of the Philosophers IV.9.66-10.67).

The Pyrrhonian Skeptics

Aenesidemus (1st century BC) broke from the "New" Academy and founded new skeptical movement named after Pyrrho (who pursued a skeptical way of life but wrote nothing and established no school).

Sextus Empiricus' Outlines of Pyrrhonism is the primary source for Pyrrhonian Skepticism.

• Sextus Empiricus. Outlines of Pyrrhonism.

"The natural result of any investigation is that the investigators either discover the object of search or deny that it is discoverable and confess it to be inapprehensible (ἀκαταληψίας) or persist in their search. So, too, with regard to the objects investigated by philosophy, this is probably why some have claimed to have discovered the truth, others have asserted that it cannot be apprehended, while others again go on inquiring. Those who believe they have discovered it are the 'Dogmatists,' especially so called—Aristotle, for example, and Epicurus and the Stoics and certain others; Cleitomachus and Carneades and other Academics treat it as inapprehensible: the Sceptics keep on searching. Hence it seems reasonable to hold that the main types of philosophy are three—the Dogmatic, the Academic, and the Sceptic. ... [O]ur task at present is to describe in outline the Sceptic doctrine, first premising that of none of our future statements do we positively affirm that the fact is exactly as we state it, but we simply record each fact, like a chronicler, as it appears to us at the moment" (Outlines of Pyrrhonism I.1.1-4).

"[It is called] 'Pyrrhonean' from the fact that Pyrrho appears to us to have applied himself to Scepticism more thoroughly and more conspicuously than his predecessors" (Outlines of Pyrrhonism I.1.7).

"The [Pyrrhonian] Sceptics, then, were constantly engaged in overthrowing the dogmas (δόγματα) of all schools, but enuntiated none themselves; and though they would go so far as to bring forward and expound the dogmas of the others, they themselves laid down nothing definitely, not even the laying down of nothing. So much so that they even refuted their laying down of nothing, saying, for instance, 'We determine nothing,' since otherwise they would have been betrayed into determining..." (Diogenes Laertius, Lives of the Philosophers XI.74).

"The originating cause of Scepticism is, we say, the hope of attaining quietude. Men of talent, who were perturbed by the contradictions in things and in doubt as to which of the alternatives they ought to accept, were led on to inquire what is true in things and what false, hoping by the settlement of this question to attain quietude (ἀταρακτήσοντες). The main basic principle of the Sceptic system is that of opposing to every proposition an equal proposition; for we believe that as a consequence of this we end by ceasing to dogmatize" (Outlines of Pyrrhonism I.1.12).

"When we say that the Sceptic refrains from dogmatizing we do not use the term 'dogma (δόγμα),' as some do, in the broader sense of 'approval of a thing (εὐδοκεῖν)' (for the Sceptic gives assent to the feelings which are the necessary results of sense-impressions, and he would not, for example, say when feeling hot or cold 'I believe that I am not hot or cold'); but we say that 'he does not dogmatize' using 'dogma' in the sense, which some give it, of 'assent to one of the non-evident objects of scientific inquiry (τινι πράγματι τῶν κατὰ τὰς ἐπιστήμας ζητουμένων ἀδήλων συγκατάθεσιν)'; for the Pyrrhonean philosopher assents to nothing that is non-evident. Moreover, even in the act of enunciating the Sceptic formulae concerning things non-evident—such as the formula 'No more (one thing than another),' or the formula 'I determine nothing,' or any of the others which we shall presently mention,—he does not dogmatize. ... in his enunciation of these formulae he states what appears to himself and announces his own impression in an undogmatic way, without making any positive assertion regarding the external realities" (Outlines of Pyrrhonism I.1.13-15).

"Adhering, then, to appearances we live in accordance with the normal rules of life, undogmatically (ἀδοξάστως), seeing that we cannot remain wholly inactive. And it would seem that this regulation of life is fourfold, and that one part of it lies in the guidance of Nature, another in the constraint of the passions, another in the tradition of laws and customs, another in the instruction of the arts. Nature’s guidance is that by which we are naturally capable of sensation and thought (αἰσθητικοὶ καὶ νοητικοί); constraint of the passions is that whereby hunger drives us to food and thirst to drink; tradition of customs and laws, that whereby we regard piety in the conduct of life as good, but impiety as evil; instruction of the arts, that whereby we are not inactive in such arts as we adopt. But we make all these statements undogmatically" (Outlines of Pyrrhonism I.1.23-24).

"We assert still that the Sceptic's End is quietude in respect of matters of opinion and moderate feeling in respect of things unavoidable. For the Sceptic, having set out to philosophize with the object of passing judgement on the sense-impressions and ascertaining which of them are true and which false, so as to attain quietude thereby, found himself involved in contradictions of equal weight, and being unable to decide between them suspended judgement; and as he was thus in suspense there followed, as it happened, the state of quietude in respect of matters of opinion. For the man who opines that anything is by nature good or bad is for ever being disquieted: when he is without the things which he deems good he believes himself to be tormented by things naturally bad and he pursues after the things which are, as he thinks, good; which when he has obtained he keeps falling into still more perturbations because of his irrational and immoderate elation, and in his dread of a change of fortune he uses every endeavour to avoid losing the things which he deems good. On the other hand, the man who determines nothing as to what is naturally good or bad neither shuns nor pursues anything eagerly; and, in consequence, he is unperturbed" (Outlines of Pyrrhonism I.1.25-28).

"[T]he Sceptics were in hopes of gaining quietude by means of a decision regarding the disparity of the objects of sense and of thought, and being unable to effect this they suspended judgement; and they found that quietude, as if by chance, followed upon their suspense, even as a shadow follows its substance. We do not, however, suppose that the Sceptic is wholly untroubled; but we say that he is troubled by things unavoidable; for we grant that he is cold at times and thirsty, and suffers various affections of that kind. But even in these cases, whereas ordinary people are afflicted by two circumstances,—namely, by the affections themselves and, in no less a degree, by the belief that these conditions are evil by nature,—the Sceptic, by his rejection of the added belief in the natural badness of all these conditions, escapes here too with less discomfort. Hence we say that, while in regard to matters of opinion the Sceptic’s End is quietude, in regard to things unavoidable it is 'moderate affection'" (Outlines of Pyrrhonism I.1.29-30).

"[A]lthough both the Academics and the Sceptics say that they believe some things, yet here too the difference between the two philosophies is quite plain. For the word 'believe' (πείθεσθαι) has different meanings: it means not to resist but simply to follow without any strong impulse or inclination, as the boy is said to believe his tutor; but sometimes it means to assent to a thing of deliberate choice and with a kind of sympathy due to strong desire, as when the incontinent man believes him who approves of an extravagant mode of life. Since, therefore, Carneades and Cleitomachus declare that a strong inclination accompanies their credence and the credibility of the object, while wea say that our belief is a matter of simple yielding without any consent (ἁπλῶς εἴκειν ἄνευ προσπαθείας)..." (Outlines of Pyrrhonism I.1.229-230).