"All Sensations Are True" - Illusions Do Not Invalidate The Senses

Epicurus saw that it is opinions which are true and false, and that the senses do not contains opinions. The senses, the feelings, and the prolepses are reported to the mind "truly," in the sense of "honestly," without containing any propositions or opinions of their own. Neither the eyes nor the ears nor any other faculty have any memory - they simply relay to the mind what they perceive at any moment.

It is in the mind where the perceptions are stored and turned into opinions about what is being perceived, and it is the mind which must undertake the task of processing the perceptions accurately. The eyes do not tell our minds what they see and the ears do not tell our minds what they hear, and so on – truth and error is in the mind, not in the faculties given by nature.

The task of determining truth is that of the mind, which requires that we understand both nature and how our faculties process the perceptions provided to us by nature, because our faculties alone are our direct contacts with outside reality. As Lucretius wrote as to our "feelings" in general: " For that body exists is declared by the feeling which all share alike; and unless faith in this feeling be firmly grounded at once and prevail, there will be naught to which we can make appeal about things hidden, so as to prove aught by the reasoning of the mind." (Book 1:418)

One very important aspect of our analysis of "all sensations are true" is that we will see how - in interpreting Epicurus - it is important to look behind a superficial analysis of his statements. Phrases like "death is nothing to us" or "pleasure is the absence of pain" or "all sensations are true" can be interpreted in multiple ways, some of which are absurd when taken literally, but profound when the deeper meaning of the words used are examined. From as far back as Epicurus' own time, through the time of Cicero, and even today, far too often Epicurus' teachings are given absurd constructions that conflict with the unmistakeable thrust of other Epicurean principles.

Epicurus is an extremely logical philosopher, and we should always look to construe his meaning by considering all of his statements as a coherent whole, never allowing ourselves to ignore any part of them, and never falling under the influence of other philosophies to construe him in ways that are foreign to his core principles.

As we will see when we examine Lucretius Book IV, the Epicureans were very familiar with the issues posed by illusions, so we must never construe the statement "all sensations are true" as if Epicurus were not fully and completely aware of the existence of illusions and the need to account for them.

The aim of this article is to show reasons for believing that the statement in the heading is false as usually understood. It is absurd; the documentation is deficient, misleading, and from prejudiced sources; advocates of its validity go beyond their authorities. It is inconsistent with Epicurus' theory of perception, his terminology, his account of vision, his classifications, his treatment of the criteria in his Principal Doctrines, his account of heavenly phenomena in the letter to Pythocles, and his recommendations to students. Ancient proofs of it are polemical sophistries. Modern misinterpretations have arisen from the ambiguity of ἀληθοῦς, which has three meanings in Epicureanism: 1. real or self- existent; 2. relatively true; 3. absolutely true. Sensations have been confused with judgments.

It is not a difficult task to find both general and specific reasons for doubting the truth of the allegation that Epicurus believed all sensations to be true in the sense of dependable. Of general reasons the most cogent is the absurdity of the idea. It contradicts human experience and tends to equate the sensations of madmen and the sane. It also diminishes the necessity of establishing the criteria of truth apart from the sensations, and it raises the question why Epicurus should have gone to such pains to set up a canon ranking in importance with his physics and ethics.

Another reason of a general nature is the character of the documentation and the bias of its sources. Explicit evidence in the literary remains of Epicurus is extremely scanty and the implicit evidence has been largely overlooked. The external testimonia derive chiefly from the writings of Cicero and Plutarch, both of whom were interested in placing Epicurus in an unfavorable light. Lastly, no ancient philosopher was so universally calumniated as Epicurus and modern scholarship has not yet emancipated itself from the entails of inherited detraction.

The zeal of these detractors is sufficient to place the impartial student keenly on his guard. John Masson wrote: "The first principle of the Epicurean theory of knowledge is that all sensations are of themselves reliable." This goes beyond all authority. Epicurus undoubtedly did say that all sensations were true but this is not to say that they are all reliable. He assumed that their reliability varied according to distances. Neither is it right to speak here of a "first principle." There can be no comparison among essentials. The canon was based upon three things, the sensations, the feelings, and the general concepts.2 These formed a tripod, and one leg of a tripod cannot be more important than another.

• Norman DeWitt - "All Sensations Are True" Transactions and Proceedings of the American Philological Association Vol. 74 (1943)

Aristotle’s attitude toward empirical method is more favorable than Plato’s; for though Aristotle denies that empirical observation alone is adequate for knowledge, yet he does regard perception as the starting-point of all knowledge. In one passage he says that each sense organ has its distinctive objects of perception, and in regard to these objects it never errs. In the Metaplzysics he traces the origin of art and science to experience and memory. The observation and memory of what is beneficial to a number of persons suffering from some disease provide the ground for a generalization about the cure of that disease. Experience is knowledge of particulars, while art is knowledge of the universal; yet knowl- edge of the universal is derived from the determination of similarities in a number of particular cases.“ In the Topics Aristotle describes the method of deriving the universal from the particular as the observation of the similar; and he asserts that this method is useful in inductive arguments, in hypo- thetical syllogisms, where inference is made from one group of objects to other objects that are similar, and even in the formulation of de¿nitions.

• Commentary by Phillip and Estelle De Lacy in "Philodemus - On Methods of Inference" p. 126 (1941)

In spite of such statements as these, Aristotle does not formulate his own scienti¿c method in purely empirical terms. He says that science requires the use of both reason and per- ception, and only once does he indicate that perception is the ultimate test. In the absence of rational explanation he refers to an empirical generalization merely as a probable conjecture.”

Aristotle regards empiricism as inadequate because he be- lieves that observation can never give necessary connections between objects. In the absence of causal knowledge the empirical scientist must base his knowledge on a study of signs, and inferences from signs are not reliable except in cases where the inferences may be converted into valid syllogisms.

• Commentary by Phillip and Estelle De Lacy in "Philodemus - On Methods of Inference" p. 127 (1941)

Constructions that were interpreted as "All Sensations Are True" and "The Size of The Sun Is As It Appears To Be" focus attention o this point and challenge us to understasnd the mind-sensation relationship properly.

This will be explained in the article by T.M. H. Gellar-Goad cited below.

One example of this is Plato's "cave" analogy.

See DeWitt's article "All Sensations Are True" and the explanation in "Epicurus and His Philosophy"

The adoption of the Euclidean textbook as a model involved, of course, the procedure by deducdve reasoning. The Twelve Elementary Principles were first stated and then demonstrated like theorems. Each theorem, in turn, once demonstrated, became available as a major premise for the deduction of subsidiary theorems. The truth of this subsidiary theorem is then confirmed by the evidence of the Sensations, which operate as criteria. The mistake of believing Epicurus to be an empiricist must be avoided; it is not his teaching that knowledge has its origin in sensation. The status of the Sensations is that of witnesses in court and is limited to confirming or not confirming the truth of a given proposition.

• Norman DeWitt "Epicurus and His Philosophy" Page 25

The status of the volitional mind, which alone is truly rational, is that of a judge presiding in court. The litigants are truth and error. The role of the Sensations, Anticipations, and Feelings is that of witnesses. The judge, as becomes his office, rejects no evidence that is pertinent; he distinguishes between mere opinion and knowledge, between the idea that awaits confirmation by additional evidence and that which is already certain, between the immediate, dependable sensation and the deceptive, distant view, between false pleasures and wholesome pleasures and between true and false concepts of abstract truth. If the mind falls short of performing these judicial functions, the conflict in the soul will be prolonged and no satisfying decision between truth and error will be attainable. This is the gist of Authorized Doctrine 24.

• Norman DeWitt "Epicurus and His Philosophy" Page 213

It remains to speak of the relatively true. The views of a tower at various distances may be cited as examples. Each is true relative to the distance; its value as evidence of the facts is another mauer. This distinction was no novelty to the ancients; Sextus Empiricus sets it forth at some length in a discussion of Epicureanism.

Also worthy of mention is the sensation which is optically true but false to the facts. An example much brandished by the skeptics was the bent image of the oar immersed in the water. Epicurus made logical provision for this difficulty: "Of two sensations the one cannot refute the other, because we give attention to all sensations." This statement alone would acquit him of belief in the infallibility of sensation, because it is distinctly implied that some sensations are employed to correct others.

The example of the tower will serve as a transition from the topic of ambiguity to that of confusion. When modern scholars seize upon the saying "all sensations are true," which appears nowhere in the extant writings of Epicurus, and stretch it to mean that all sensations are reliable or trustworthy or "that the senses cannot be deceived," they are confusing the concept of truth with the concept of value. They overlook the fact that even a truthful witness may fall short of delivering the whole truth or may even give false evidence. The distant view of the square tower is quite true relative to the distance but it fails to reveal the whole truth about the tower.

To assume that Epicurus was unaware of these plain truths. as one must if belief in the infallibility of sensation is imputed to him, is absurd. It is because he was aware that the value of sensations, apart from their truth, varied all the way from totality to zero, that he exhorted beginners "under all circumstances to watch the sensations and especially the immediate perceptions whether of the intellect or any of the criteria whatsoever." Obviously, so far from thinking the sensations infallible, he was keenly aware of the possibility of error and drew sharp attention to the superior values of immediate sensations.

When once these ambiguities and confusions have been discerned and eliminated, it is possible to state the teaching of Epicurus with some of that precision by which he set high store. In the meaning of the Canon, then, a sensation is an aisthesis. All such sensations may possess value; otherwise there would be no sense in saying. "We pay attention to all sensations." Their values, however, range all the way from totality to zero. The value is total only when the sensation is immediate. For example, when Aristotle says, "The sense of sight is not deceived as to color," this is true only of the close view, because colors fade in more distant views.

Sensations, however, usually present themselves in combinations of color, shape, size, smell, and so on. An immediate presentation of such a composite unit is a phantasia. All such presentations are true, but they do not rank as criteria in the meaning of the Canon, for the reason that the intelligence has come into play. An act of recognition (epaisthesis) has taken place in the mind of the observer, which is secondary to the primary reaction that registered color, shape, size, smell, and so forth. That Epicurus did not regard these composite sensations as criteria is made clear by a statement of his own: "The fidelity of the recognitions guarantees the truth of the sensations." For example, the animal standing yonder is recognized as a dun-colored ox. This is a secondary reaction. Only the primary perceptions of color, shape, size, and so on constitute a direct contact between man and the physical environment. The truth of these perceptions is confirmed by the fidelity of the recognition.

Again, let it be assumed that the quality of sweetness is registered by sensation. It is not, however, sensation that says, "This is honey"; a secondary reaction in the form of a recognition involving intelligence has taken place. This, in the terminology of Epicurus, is "a fantastic perception of the intelligence." These were not given the rank of criteria by Epicurus for the reason already cited. It is on record, however, that later Epicureans did so.

So far is Epicurus from believing all sensations to be true in the meaning of the Canon that he guards against error in various ways. In the first place, attention must be paid to all sensations, as already mentioned. Next, the sensations of the individual must be checked by those of others: "Consequently attention must be paid to the immediate feelings and to the sensations, in common with others in matters of common concern and individually in matters of private concern and to all clear presentations of every one of the criteria." This guardedness was imperative, because contemporary skepticism was flourishing. The problem of skepticism is attacked disjunctively in the Authorized Doctrines: either all sensations are rejected as valid evidence or some are admitted and some rejected. The former procedure is dealt with in Doctrine 23: "If you are going to make war on all the sensations, you will not even have a standard by reference to which you shall judge those of them which you say are deceptive." This makes it plain once more that not all sensations are true but the validity of some must be checked by the evidence of others.

The Doctrine above is directed at the outright skeptics. The second limb of the disjunctive approach deals with the Platonists, who rejected terrestrial phenomena as deceptive while accepting the evidences of celestial phenomena. Epicurus denied "clear vision (phantasia) from distances, if only the text be not emended. He wrongly insisted that heavenly phenomena could be explained from the terrestrial. This betrayed him into committing his most notorious blunder; for the reason that the magnitude of a fire does not seem to diminish with distance as does that of concrete objects he declared the sun to be no larger or only a little larger than it appears to be. This ridiculous judgment calls for no comment, but it may be mentioned that Plato's belief in astral gods, however grandiose, is no more acceptable. Epicurus not only censured Plato for accepting the evidence of celestial phenomena while rejecting that of terrestrial phenomena but also condemns him as a mythologer: "'Whenever a man admits one phenomenon and rejects another equally compatible with the phenomenon in question, it is manifest that he takes leave of all scientific study of nature and takes refuge in mythology." Hostility to Plato was combined in this case with contempt of mythology.

Nevertheless Doctrine 23 throws light upon the working of the mind in respect of the criteria. Mental activity may be automatic or volitional. It is the automatic mind that errs; it may judge the distant tower to be round; this is the error of "opinion." The discreet observer knows the distant view to be deceptive and suspends judgment until the tower is observed at close hand. A tentative judgment is then confirmed or disproved. In the case of the size of the sun, which is visible but never at close hand, the judgment held good, as Epicurus believed, because not contradicted.

The sensations are consistently regarded as witnesses in court. Their evidence may be false, as in the case of the oar half-immersed in the water, which appears to be bent. False evidence is to be corrected by that of other sensations. The evidence of all witnesses must receive attention. The volitional mind, as opposed to the automatic mind, which errs, functions as judge.

By way of concluding this account of the Sensations as criteria it is well to present a synoptic view of the evidence. Nowhere in our extant Little Epitome or the Authorized Doctrines do we find the statement "that all sensations are true." On the contrary, the Epitome begins by urging the student "to give heed to the sensations under all circumstances and especially the immediate perceptions whether of the intelligence or of any criterion whatsoever," which manifestly allows some value to all sensations and special value to immediate sensations. At the end of the Epitome the student is warned to check his own observations by those of others. These authentic statements are incompatible with belief in the infallibility of sensation. They presume belief in gradations of value among sensations and also the need of perpetual caution against error.

Of three Authorized Doctrines devoted to the topic, 23, 24, and 25, the first urges attention to "all the clear evidence"; the second warns that the rejection of all the sensations leaves the observer without the means of checking sensation by sensation; the third warns of the confusion resulting from rejecting any particular sensation. All of these are of the nature of warnings and completely belie the reckless verdict of an otherwise meticulous scholar "that the Epicureans boldly said that every impression of sense is true and trustworthy."

Lastly, in every instance above mentioned the word for sensation is aisthesis and not phantasia. That somewhere Epicurus had actually written "all phantasias are true" seems certain; in which of his writings it is unknown, but the evidence is sufficient. This statement, as being assailable, was pounced upon by his detractors and zealously ventilated. If, however, the extant texts of Epicurus be taken as a guide. the phantasia or "fantastic" perception is merely the highest grade of evidence; the aisthesis, the perception of particulars, is the criterion.

• Norman DeWitt, "Epicurus And His Philosophy" page 138

Lucretius Book IV:

[353] And when we see from afar off the square towers of a town, it comes to pass for this cause that they often look round, because every angle from a distance is seen flattened, or rather it is not seen at all, and the blow from it passes away, nor does its stroke come home to our eyes, because, while the idols are being borne on through much air, the air by its frequent collisions constrains it to become blunted. When for this cause every angle alike has escaped our sense, it comes to pass that the structures of stone are worn away as though turned on the lathe; yet they do not look like things which are really round to a near view, but a little resembling them as though in shadowy shape.

[364] Likewise our shadow seems to us to move in the sunshine, and to follow our footsteps and imitate our gait; if indeed you believe that air bereft of light can step forward, following the movements and gait of men. For that which we are wont to name a shadow can be nothing else but air devoid of light. But in very truth it is because in certain spots in due order the ground is bereft of the light of the sun wherever we, as we move on, cut it off, and likewise the part of it which we have left is filled again; for this cause it comes to pass that, what was but now the shadow of our body, seems always to follow unaltered straight along with us. For always new rays of light are pouring out, and the former perish, like wool drawn into a flame. Therefore readily is the ground robbed of light, and is likewise filled again and washes away its own black shadows.

[379] And yet we do not grant that in this the eyes are a whit deceived. For it is theirs to see in what several spots there is light and shade: but whether it is the same light or not, whether it is the same shadow which was here, that now passes there, or whether that rather comes to pass which I said a little before, this the reasoning of the mind alone must needs determine, nor can the eyes know the nature of things. Do not then be prone to fasten on the eyes this fault in the mind.

[387] The ship, in which we journey, is borne along, when it seems to be standing still; another, which remains at anchor, is thought to be passing by. The hills and plains seem to be flying towards the stern, past which we are driving on our ship with skimming sail.

[391] All the stars, fast set in the vault of the firmament, seem to be still, and yet they are all in ceaseless motion, inasmuch as they rise and return again to their distant settings, when they have traversed the heaven with their bright body. And in like manner sun and moon seem to abide in their places, yet actual fact shows that they are borne on.

[397] And mountains rising up afar off from the middle of the waters, between which there is a free wide issue for ships, yet seem united to make a single island.

[400] When children have ceased turning round themselves, so sure does it come to appear to them that the halls are turning about, and the pillars racing round, that scarcely now can they believe that the whole roof is not threatening to fall in upon them.

[404] And again, when nature begins to raise on high the sunbeam ruddy with twinkling fires, and to lift it above the mountains, those mountains above which the sun seems to you to stand, as he touches them with his own fire, all aglow close at hand, are scarce distant from us two thousand flights of an arrow, nay often scarce five hundred casts of a javelin: but between them and the sun lie the vast levels of ocean, strewn beneath the wide coasts of heaven, and many thousands of lands are set between, which diverse races inhabit, and tribes of wild beasts.

[414] And yet a pool of water not deeper than a single finger-breadth, which lies between the stones on the paved street, affords us a view beneath the earth to a depth as vast as the high gaping mouth of heaven stretches above the earth; so that you seem to descry the clouds and the heaven and bodies wise hidden beneath the earth—yet in a magic sky.

[420] Again, when our eager horse has stuck fast amid a river, and we look down into the hurrying waters of the stream, the force seems to be carrying on the body of the horse, though he stands still, athwart the current, and to be thrusting it in hot haste up the stream; and wherever we cast our eyes all things seem to be borne on and flowing forward, as we are ourselves.

[426] Though a colonnade runs on straight-set lines all the way, and stands resting on equal columns from end to end, yet when its whole length is seen from the top end, little by little it contracts to the pointed head of a narrow cone, joining roof with floor, and all the right hand with the left, until it has brought all together into the point of a cone that passes out of sight.

[432] It happens to sailors on the sea that the sun seems to rise from the waves, and again to set in the waves, and hide its light; since verily they behold nothing else but water and sky; so that you must not lightly think that the senses waver at every point.

[436] But to those who know not the sea, ships in the harbour seem to press upon the water maimed, and with broken poop. For all the part of the oars which is raised up above the salt sea spray, is straight, and the rudders are straight above; but all that is sunk beneath the water, seems to be broken back and turned round, yes, and to turn upwards again and twist back so that it almost floats on the water’s surface.

[443] And when winds in the night season carry scattered clouds across the sky, then the shining signs seem to glide athwart the storm-clouds, and to be moving on high in a direction far different from their true course.

[447] Then if by chance a hand be placed beneath one eye and press it, it comes to pass by a new kind of perception that all things which we look at seem to become double as we look, double the lights of the lamps with their flowery flames, double the furniture throughout the whole house in twin sets, and double the faces of men, double their bodies.

[453] Again, when sleep has bound our limbs in sweet slumber, and all the body lies in complete rest, yet then we seem to ourselves to be awake and moving our limbs, and in the blind gloom of night we think to see the sun and the light of day, and, though in some walled room, we seem to pass to new sky, new sea, new streams, and mountains, and on foot to cross over plains, and to hear sounds, when the stern silence of night is set all about us, and to give answer, when we do not speak.

[462] Wondrously many other things of this sort we see, all of which would fain spoil our trust in the senses; all in vain, since the greatest part of these things deceives us on account of the opinions of the mind, which we add ourselves, so that things not seen by the senses are counted as seen. For nothing is harder than to distinguish things manifest from things uncertain, which the mind straightway adds of itself.

[469] Again, if any one thinks that nothing is known, he knows not whether that can be known either, since he admits that he knows nothing. Against him then I will refrain from joining issue, who plants himself with his head in the place of his feet. And yet were I to grant that he knows this too, yet I would ask this one question; since he has never before seen any truth in things, whence does he know what is knowing, and not knowing each in turn, what thing has begotten the concept of the true and the false, what thing has proved that the doubtful differs from the certain?

[478] You will find that the concept of the true is begotten first from the senses, and that the senses cannot be gainsaid. For something must be found with a greater surety, which can of its own authority refute the false by the true. Next then, what must be held to be of greater surety than sense? Will reason, sprung from false sensation, avail to speak against the senses, when it is wholly sprung from the senses? For unless they are true, all reason too becomes false. Or will the ears be able to pass judgement on the eyes, or touch on the ears? or again will the taste in the mouth refute this touch; will the nostrils disprove it, or the eyes show it false? It is not so, I trow. For each sense has its faculty set apart, each its own power, and so it must needs be that we perceive in one way what is soft or cold or hot, and in another the diverse colours of things, and see all that goes along with colour. Likewise, the taste of the mouth has its power apart; in one way smells arise, in another sounds. And so it must needs be that one sense cannot prove another false. Nor again will they be able to pass judgement on themselves, since equal trust must at all times be placed in them. Therefore, whatever they have perceived on each occasion, is true.

[500] And if reason is unable to unravel the cause, why those things which close at hand were square, are seen round from a distance, still it is better through lack of reasoning to be at fault in accounting for the causes of either shape, rather than to let things clear seen slip abroad from your grasp, and to assail the grounds of belief, and to pluck up the whole foundations on which life and existence rest. For not only would all reasoning fall away; life itself too would collapse straightway, unless you chose to trust the senses, and avoid headlong spots and all other things of this kind which must be shunned, and to make for what is opposite to these. Know, then, that all this is but an empty store of words, which has been drawn up and arrayed against the senses.

[513] Again, just as in a building, if the first ruler is awry, and if the square is wrong and out of the straight lines, if the level sags a whit in any place, it must needs be that the whole structure will be made faulty and crooked, all awry, bulging, leaning forwards or backwards, and out of harmony, so that some parts seem already to long to fall, or do fall, all betrayed by the first wrong measurements; even so then your reasoning of things must be awry and false, which all springs from false senses.

[522] Now it is left to explain in what manner the other senses perceive each their own object—a path by no means stony to tread.

The process works this way:

The process may be stated as a formula or as an equation: sensation plus general concept equals a recognition. When this is fulfilled the sensation is true. Laertius states it clearly as a general principle:10 'the fact of the occurrence of the recognitions guarantees the truth of the sensations.' This statement, however, implies a negative: 'the non-occurrence of the recognitions reveals the falsity or indecisiveness of the sensations.' This would be the case if the horse or the cow were so distant or the light so dim that recognition was impossible. If, on the contrary, all sensations were true, as is alleged, every sensation would result in a recognition and there would be no difference between an αἴσθησις and an ἐπιβολή, which is so absurd as to call for no further argument.

• Norman DeWitt - "All Sensations Are True" Transactions and Proceedings of the American Philological Association Vol. 74 (1943) page 20

[91] The size of sun (and moon) and the other stars is for us what it appears to be; and in reality it is either (slightly) greater than what we see or slightly less or the same size: for so too fires on earth when looked at from a distance seem to the senses. And every objection at this point will easily be dissipated, if we pay attention to the clear vision, as I show in my books about nature.

• Epicurus' letter to Pythocles

See the article "Lucretius on the Size of the Sun", by T.H.M. Gellar-Goad https://www.epicureanfriends.com/thread/2550-lucretius-on-the-size-of-the-sun-by-t-h-m-gellar-goad/?postID=18347&highlight=%2522Sun%2BIs%2BThe%2BSize%2522#post18347

Size of the Sun as Didactic Challenge

Getting to this state of reasoned aporia is no simple task, as my ruminations above indicate. The text of DRN presents what can be taken on a simple surface reading to mean that the sun is the size of a soccer ball, a claim that may strike ancient and modern readers alike as patently ridiculous. I suggest that the complication and the seemingly questionable wording are part of the point of the passage, a call for us to apply our Epicurean philosophical and critical thinking to a knotty problem. In this respect, the Lucretian presentation of the size of the sun can be compared to the role of hunting imagery throughout the poem (Whitlatch: 2014) or the final-exam interpretation of the plague scene at the poem’s end (e.g., Clay: 1983, 257-266). Each of the three constitutes a didactic challenge to the reader, whose successful progression through the Lucretian narrator’s didactic plot entails solving the riddle it presents.

A principal element of the response to the solar challenge is to think about optics and perspective when it comes to figuring out the size of the sun. Contrary to Barnes’ claim that “there is virtually no evidence on how the Epicureans understood the perception of size,” recent scholarship on perspective in the atomic theory of Democritus gives ample clues for Epicurus’ own thinking, which can in turn be confirmed as Epicurean by examination of relevant passages elsewhere in Lucretius’ DRN. Kelli Rudolph’s study of Democritus clarifies the theoretical function of eidola in the perception of size in relation to distance. Rudolph also explores the importance of Democritus’ metaphor of wax impressions for his atomic theory of vision: Because “a wax impression is an isomorphic copy of the original, but never an exact replica” (2011, 79), the eidolic-vision theory of Democritus allows for “epistemic uncertainty in the images we see” (80). Since, according to Democritus, sight consists in the physical reception of physical emissions from viewed bodies, the objects so viewed and visions of them should not be considered identical, because the εἴδωλον of the thing is never the thing itself. For Epicurus and his followers who have adopted Democritean atomism and optics, therefore, visual sensation – though it may (inasmuch as it is a sense-perception) be infallible – requires active cognition in order for sensations to be properly related to and with their sources.

We can verify that some such theory of vision at a distance is in force in DRN by considering passages that deal with perspective in the treatment of simulacra in Book 4. The main description of how we are able to judge distance by sight appears at 4.244-255. In essence, the image emitted by the perceived object to the viewer pushes the intervening “air” (aer, 247-251) past the viewer’s eyes, and the quantity of the air is directly proportional to the distance between viewer and viewed. That the sun falls into the category of distant objects requiring intentional perspective-taking along these lines is arguably obvious, but is also suggested by the Lucretian speaker’s explanation, shortly thereafter in the same book, of the sun’s blinding power (4.325-328). According to the Lucretius-ego, the sun is endowed with great power even though it is shining from on high (vis magnast ipsius . . . alte, 326); the sun’s simulacra, therefore, as they travel through air (aera per purum, 327, a phrase that looks back to the importance of air in 4.244-255), can strike the eyes heavily enough to harm their atomic compounding. From these lines the reader can determine that the sun is not entirely a special case, but is subject to the same air-based perspectival adjustments as are other observable objects.

The image most often cited by scholars examining the Lucretian treatment of perspective is that of the tower seen from far away (4.353-363), which is square but appears at a distance to be round. According to the speaker’s explanation for the apparent roundness of the tower’s “angle” (angulus, 355), “while the simulacra are moving through a lot of air, the air with constant collisions forces it [the angle] to become dull” (aera per multum quia dum simulacra feruntur, | cogit hebescere eum crebris ostensibus aer, 358-359). As a result, “every angle all at once has escaped our perception” (suffugit sensum simul angulus omnis, 360). That the tower appears round does not make it round; that the tower is in reality square does not invalidate our perceiving it as having a round appearance from a distance. The fact that the Lucretian discussion of the size of the sun invokes readers’ sense-perception (with videtur at 5.565, inter alia) prompts them to think back to the Lucretian discussion of perception at a distance, and to recall from the tower example that data derived from visual perception degrades over distance along with the simulacra themselves. We know intuitively that the sun is farther away than such a tower, and thus we know that we need care in assessing the size of the sun, just as we would in assessing the size (and shape) of a far-off tower.

Finally, there must be perspective-taking on our tactile sensation of warmth as well as on our sight. The heat emitted by a candle, by a bonfire and by a burning building fades away at profoundly different distances – an important piece of evidence in figuring out just how big the sun appears to be. Similarly, the Lucretian speaker’s explicit introduction of heat into the Epicurean doctrine on the size of the sun may suggest to readers that they ponder as well the difference in perceived heat transmitted by the sun and the moon, despite the roughly equivalent percentage of the sky they fill – attested by, among other things, the moon’s ability to eclipse the sun for terrestrial viewers. Vision alone, it appears, is insufficient for solving the puzzle.

So the implied prompts to remember the role of heat in addition to light, and to apply our understanding of perspective to the question of the size of the sun, amount to another current in the didactic airstream of DRN. The Lucretian speaker, rather than merely parroting a ruthlessly ridiculed doctrine, instead pulls his student-readers into the process of inquiry. It becomes the didactic audience’s task to receive data from sense-perception, and to use lessons learned earlier in the poem (as about perspective and distance, cf. 4.239-268, 353-363) in making correct rational judgments based upon that sense data. Asmis reminds us that for the Lucretius-ego “there is no clash between the judgment of the senses and objective reality, because the type of fact that seems to be in conflict with sense perception does not fall within the province of sense perception at all, but belongs to an entirely distinct domain of reality . . . judged by reason.” As Demetrius Lacon writes of a related solar question, “the sun does not appear stationary, but rather it is thought to appear stationary” (Greek omitted, PHerc. 1013 col. 20.7-9; cited by Barnes: 1989, 35-36 n.36). Tricky cases such as the size of the sun, where sense data is incomplete, may require suspension of such reasoned judgment, until enough evidence becomes available to evaluate our hypotheses through the process of ἐπιμαρτύρησις, until which point the opinion must remain a προσμένον.

In the Epicurean and Lucretian account of reality, the senses themselves are infallible. The Lucretian speaker’s assertion that the sun is just as big as it is perceived to be by our senses must therefore also be infallible – just as the perception that the sun is bigger when it is close to the horizon at sunrise and sunset must be infallible, without our having to believe that the sun actually changes sizes dramatically during the day. But our interpretation of what exactly that assertion entails about the sun’s actual size is a matter of judgment, and as such is fallible and uncertain indeed. As with the argumentation presented by the Lucretius-ego throughout the poem, and as with the gripping, awful plague scene at the end of Book 6, we must be keen-scented, relentless and detached from mundane concerns and fears in order to reckon and judge accurately in cosmic matters.

• Gellar-Goad "Lucretius On The Size of The Sun," from "Epicurus in Rome, Philosphical Perspectives in the Roman Age"

Size of the Sun as Epicurean Shibboleth

The Epicureans did not believe that the sun was the size of a human foot. They distinguished between the sun’s actual size and the size of its appearance, the latter of which was the only magnitude measurable from earth with the technology available. In this matter as almost everywhere else, the Epicureans appealed to the truth of sense-perception – with the important caution that discerning reality from appearance requires perception-based judgment, which itself is not guaranteed to be true. In Lucretius’ poem, the discussion of solar magnitude adds more detail to Epicurus’ original conception, especially with the introduction of the sun’s heat into the passage. Complicated style emphasizes how full of hedges and conditioned claims the Lucretius-ego is, and his thorny exposition of the doctrine amounts to a didactic challenge that sends readers elsewhere in his work, to ponder perspective and to hunt down a proper understanding of this aspect of the natural world.

By staking out a stance of aporia conditioned by sense-perception and reasoning thereupon, the Epicureans did in fact prove to be less wrong than everyone else. Algra emphasizes that “all ancient estimates of the size of the sun, including those put forward by the mathematical astronomers, were false.”The failing of ancient mathematical science in estimate- making was pervasive since, Geoffrey Lloyd notes, “an important recurrent phenomenon in Greek speculations about nature is a premature or insecurely grounded quantification or mathematicisation.” Epicurus and his school, in avoiding a concrete statement of the sun’s size, avoided being concretely wrong, in contrast to Eudoxus and all the rest. The sun passage in DRN pushes the reader towards non-commitment rather than risking such a misjudgment.

In closing I argue that the size of the sun is an Epicurean shibboleth. In Epicurus,in Lucretius and in Demetrius,we see the same nostrum repeated, with progressive elaborations that do not fully clarify the basic precept. The persistence of Epicureans in this formulation is not so much the result of reflexive dogma or pseudo-intellectual obscurantism as it is a passphrase, a litmus test. Think like an Epicurean, and you will figure out that the sun’s appearance and the sun itself are two related but distinct things with two different sizes; that you must keep the infallible data of the senses, tactile as well as visual, in proper perspective when making judgments about your perception; and that the available data is insufficient to estimate the sun’s magnitude to an acceptable degree of confidence (compare Barnes: 1989, 36). Think that Epicureans believe the sun’s diameter is a foot,that they are absurd,and you have exposed yourself as un-Epicurean. The first/second-century AD Stoic doxographer Cleomedes, who as Algra points out “nowhere takes account of the Epicurean principle of multiple explanations,”likewise fails this test when he mocks Epicurus’ position on the size of the sun.

Thinking like an Epicurean – rather than figuring out the actual size of the sun – is, I suggest, the point of the Lucretian passage on the size of the sun, as it is indeed the fundamental point of Epicurean natural philosophy generally. Constantina Romeo suggests that Epicurus’ moral program of liberating humankind from the fear of death motivates his followers’ ardent defense of his claims on the sun’s size. Since Epicurus presented understanding of the natural and celestial world as essential for a life of ataraxia, “nel momento in cui lo Stoico ritiene di avere dimostrato l’errore di Epicuro nella scienza della natura, sostiene pure che Epicuro non ha dato nessun conforto di fronte alla morte” (“in the moment in which the Stoic [Posidonius] thinks he has shown Epicurus’ mistakes in natural science, he also claims that Epicurus has provided no comfort in the face of death”).

Yet Posidonius has actually failed the test, has misunderstood the stakes of the debate. Precise measurement of the sun’s size is not what is at issue for the Epicureans, and so proof of scientific error does not vitiate Epicurus’ moral philosophy. The Epicureans pushed back so fiercely against their opponents’ (mis)characterizations of Epicurus’ position because of the underlying epistemological and phenomenological principles. It does not matter to Epicurean ethics or to ataraxia whether the size of the sun is known. After all, the Epicureans did not even need to afix a certain size to the sun to accomplish their core epistemological objective: to remove anxiety about divine control over cosmological phenomena. What matters, and the underlying reason for this Epicurean shibboleth, is a readiness to use careful reasoning and good judgment to embrace uncertainty about the nature of things without succumbing to the anxiety-inducing fear of death.

• Gellar-Goad "Lucretius On The Size of The Sun," from "Epicurus in Rome, Philosphical Perspectives in the Roman Age"

[86] We must not try to force an impossible explanation, nor employ a method of inquiry like our reasoning either about the modes of life or with respect to the solution of other physical problems: witness such propositions as that ‘the universe consists of bodies and the intangible,’ or that ‘the elements are indivisible,' and all such statements in circumstances where there is only one explanation which harmonizes with phenomena. For this is not so with the things above us: they admit of more than one cause of coming into being and more than one account of their nature which harmonizes with our sensations.

[87] For we must not conduct scientific investigation by means of empty assumptions and arbitrary principles, but follow the lead of phenomena: for our life has not now any place for irrational belief and groundless imaginings, but we must live free from trouble.

Now all goes on without disturbance as far as regards each of those things which may be explained in several ways so as to harmonize with what we perceive, when one admits, as we are bound to do, probable theories about them. But when one accepts one theory and rejects another which harmonizes as well with the phenomenon, it is obvious that he altogether leaves the path of scientific inquiry and has recourse to myth. Now we can obtain indications of what happens above from some of the phenomena on earth: for we can observe how they come to pass, though we cannot observe the phenomena in the sky: for they may be produced in several ways.

[88] Yet we must never desert the appearance of each of these phenomena, and further, as regards what is associated with it, must distinguish those things whose production in several ways is not contradicted by phenomena on earth.

• Epicurus' letter to Pythocles