Epicurus’ Letter to Pythocles – Elemental Edition

With today’s release of the Letter to Pythocles, I have now completed these “Elemental Editions” of each of Epicurus’ three letters from Diogenes Laertius, plus a version of the Inscription of Diogenes of Oinoanda, and the “Defense of Epicurus” from Cicero.  I hope you find them helpful.  An MP3 version can be downloaded here.

Epicurus’ Letter to Pythocles. Elemental Edition.


This presentation of the letter to Pythocles is a project of New Epicurean.com, based on the translation of Charles D. Yonge. What you are about to hear is not a literal reading of Yonge’s translation, but a version rendered into modern American English and organized for audio presentation. The following text has been abridged, omitting the details of a number of matters such as hurricanes and earthquakes. Questions about these are resolved in the same manner as those matters which are included here. The listener should consult literal translations of the full text for comparison purposes, and should ultimately refer to the letter in its original Greek as preserved by Diogenes Laertius.

The letter to Pythocles is the second in the trilogy of letters which Epicurus wrote to summarize the core aspects of his philosophy. In contrast to the letter to Herodotus, this letter focuses on the problem of explaining the things we see in the sky above, rather than on matters which are directly before us here on earth. This change in focus allows us to see one of the most essential aspects of the Epicurean Canon of Truth. Heavenly phenomena are classic examples of matters about which we have only limited evidence. In these situations, where the evidence is not sufficient to reach a conclusion with certainty, the wise man must hold back from pronouncing judgment, and must “wait” for additional evidence. In the meantime, unless and until more evidence is found, the wise man will be very careful about labelling a theory as true or false. He will pronounce only that some theories are possible, because they are in accord with the evidence, or that some theories are not possible, because they conflict with the evidence, or that some theories, which are possible, are more likely than others, due to the weight of the evidence that supports each one.

The importance of this rule will be seen most starkly in regard to Epicurus’ view of the size of the sun. This question was of particular importance, because the Platonists, who Epicurus strongly opposed, had argued that the sun and the stars were of immense size. The Platonists were interested in this issue because they also held the sun and the stars to be gods, which directed not only their own motions through the skies, but also the affairs of men on earth. The Platonists supported these arguments with their work in mathematics and geometry, which they pursued as a kind of mystical numerology and astrology.

Epicurus responded by first pointing out that the evidence available in astronomical matters is not sufficient to establish any theory with certainty. He then set forth the view he favored himself, that the sun should not be considered to be of immense size, but only about the size that it appears to our eyes. He supported this argument by the observation that, here on earth, the light from fires does not appear to grow smaller as it recedes in the distance as fast as does the appearance of other objects. From this, and in the absence of accurate knowledge of the distances involved, Epicurus constructed an evidence-based argument with which to oppose the astrology of the Platonists.

Although we now know that, in regard to the size of the sun, Epicurus predicted wrongly, the method of thinking he employed remains valuable, and by studying his reasoning we can observe the application of several of Epicurus’ most important Canonic rules.

First, where evidence is conflicting, certainty must not be claimed.

Second, where a new theory supposes a matter that would conflict with a fact that has previously been established with certainty, the new theory must be rejected. Here, the supposition of the Platonists, that the sun was of immense size, was based in part on their theory that the sun was a god. For Epicurus, the act of hurtling through space, as an immense ball of fire, would conflict with men’s clear anticipations of divine nature as calm and blissfully happy, so the supposition must be rejected.

Third, care must always be taken to distinguish between those things which are transitory, and therefore “incidental,” and those things which are fundamental and eternal. Incidental properties change, but the ultimate properties of the elements are eternal, and never change. In remaining always the same, the properties of the elements set the limits and boundaries of what can, and what cannot, occur. Here, the sun and the stars are observed to have sizes and appearances that change, and these aspects are therefore incidental. As Epicurus had previously explained in his letter to Herodotus, incidental matters may vary, according to our perception of them, and so these must be judged in accord with the way they appear to our senses. On the other hand, the fundamental properties of the elements do not change, and from this we have confidence that only certain things are possible. No matter what size the sun and stars are theorized to be, they are clearly observed to be balls of fire hurtling through the skies. The act of hurtling through the sky as a fireball is not consistent with our anticipations of true divinity, so the sun and stars cannot be gods.

Thus in the question that was of supreme importance to human life, that of whether the sun and stars are gods that control the affairs of men, the Epicurean method led to the correct conclusion, while Platonic rationalism led to the wrong conclusion. Even without the tools of modern science, Epicurus had correctly determined that, no matter their size, the sun and stars were not gods to be worshipped. In contrast, the Platonists, carrying the banner of mathematical logic, concluded that the sun and stars were gods which guided the affairs of men. This error led the Platonists on, unchecked, in their vain pursuit of a worthless astrology, and even infected later generations, who grafted the same Platonic errors into their own religious speculations.

Those who are tempted to dismiss Epicureanism, either because of the ancient dispute about the size of the sun, or because of the modern Platonism embedded in some theories of quantum physics, are best answered by a response recorded by Cicero, two thousand years ago, in the following passage.

“You amuse yourself by thinking that Epicurus was uneducated. The truth is that Epicurus refused to consider any education to be worthy of the name if it did not teach us the means to live happily. Was Epicurus to occupy himself, like Plato, with music and geometry, arithmetic and astronomy, which are at best mere tools, and which, if they start from false premises, can never reveal truth or contribute anything to make our lives happier, and therefore better? Was Epicurus to study the limited arts, such as these, and neglect the master art, so difficult, but correspondingly so fruitful, the art of living? No! It was not Epicurus who was uninformed. The truly uneducated are those who ask us to go on studying, until old age, the subjects that we ought to be ashamed that we did not learn when we were children!”

And now, the letter to Pythocles.


Epicurus to Pythocles, wishing he may do well.

Cleon has brought me your letter, in which you continue to show toward me an affection worthy of the friendship which I have for you. You devote all your care, you tell me, to engraving in your memory those ideas which contribute to the happiness of life. At the same time, you ask me to send to you a simple outline of my ideas on astronomy, in order that you may remember them without difficulty. For you say that what I have written on this subject in my other works is difficult to remember, even with continual study.

I willingly yield to your desire, and I have good hope that, in fulfilling what you ask, I shall also be useful to many others, especially to those who are still novices in the real knowledge of Nature, and to those for whom the perplexities and the ordinary affairs of life leave but little time for leisure. Be careful, then, to seize on these precepts thoroughly. Engrave them deeply in your memory, and meditate on them along with the outline that I have previously written and addressed to Herodotus, which I also send to you.

First, remember that the only aim of knowledge of astronomy is a firm understanding that gives rise to calmness and freedom from anxiety, as this is the aim of every science.

It is not good to desire those things that are impossible, so it is not good to attempt to define a uniform theory about everything. Accordingly, we should not seek to adopt here in astronomy the method which we have followed in our researches in ethics, or in natural philosophy. In those areas, we were able to say, for instance, that there are no other things except matter and void, and that the particles provide the principles that explain all things, and so on. We were able to give a precise and simple explanation for every fact, and conform our explanation to the observable evidence.

We cannot act in the same way with respect to astronomical matters. The things we observe in the sky may arise from several different causes, and therefore we can name a number of different theories that would all be in agreement with the observations of our senses. In these astronomical matters, we do not have sufficient evidence to reason definitively, and to lay down new principles which can be relied upon with certainty for the further interpretation of Nature. The only guides for us to follow are the appearances themselves. Our purpose is not to produce a set of elaborate theories and vain opinions, but to produce a life exempt from every kind of false fear.

The things we see in the sky will not inspire alarm in us if we can avoid relying on sheer speculation to explain them, and if we can instead determine reasonable explanations that are consistent with the evidence that we can observe. But if we abandon true reasoning, and renounce the effort to seek explanations that are both consistent with the evidence we can observe in the sky, and also consistent with similar phenomena we observe here on earth, then we place ourselves far outside the science of Nature, and we fall headlong into fantasies and fables.

It is possible that the celestial phenomena may simply appear to be like phenomena we see around us here on earth, without there really being any true similarity. For the heavenly phenomena may be produced by many different causes, and we do not have sufficient evidence to know which causes are correct. Nevertheless, the only logical course for us to follow is to observe the evidence that is available, seek to distinguish the circumstances in which that evidence appears, and then compare that evidence to similar phenomena here on earth, which arises before our own eyes, and about which we have sufficient evidence for certainty.

When we use the term “world,” we mean not only the earth itself, but also a collection of things embraced by the heaven, containing the moon, the stars, and all visible objects. This collection, separated from the infinite, is terminated by an extremity. This extremity may be either thin, or dense, or revolving, or in a state of repose, or round, or triangular, or some other shape. Any of these may be true, but we must remember that everything in this world was formed from the elements at some point in the distant past, and will be destroyed back to elements at some point in the future. Any of these theories may be considered true so long as the theory does not contradict a fact that we can observe here, on our earth, that proves otherwise. It is easily seen also that the number of worlds similar to our own throughout the universe is infinite in number, as is the fact that the space between the worlds is also made up of matter and void, and not absolutely empty as some philosophers pretend.

One theory on how worlds are produced is that suitable elemental seeds emanate, either from one or more existing worlds, or from the area that is between existing worlds, and these elements flow towards a particular point where they become collected together and organized. After that, other seeds come together with these, in such a way as to form a durable whole, which might be thought of as a nucleus to which all successive elemental additions unite themselves.

In this question of formation of worlds, we must not be content with saying, as some natural philosophers do, that the elements which come together to form worlds come from the void itself, under the influence of “necessity” or “fate.” These men say that the body which is thus produced increases in size until it comes to crash against some other body, but this is contrary to the evidence, for nothing can come from the void, which is nothing.

It is also theorized that the sun, the moon, and the other lights we see in the sky were originally formed separately, and were afterwards brought into the entire total of what we call our world. All the other objects contained in our world, for instance, the earth and the sea, were also formed spontaneously, and subsequently gained size, by the addition and movement of light substances, similar to elemental fire and air, or both. This explanation is in accord with what we observe with our senses.

As to the size of the sun and of the other stars, we believe them to be approximately the same size that they appear to be. The only evidence we have as to this is what we see, and based on what we see the sun may be larger or smaller than the size it appears to be, or about the same. We base this on the fact that when we observe fires at a distance, they do not appear to shrink in size so much as do other objects. But all the difficulties on this subject will be easily dismissed if one always remembers to separate clearly in your mind those things which are certain from those things which are not certain, as I have shown in my books about Nature.

The rising and setting of the sun, of the moon, and of the stars, may have a variety of causes. It is possible that they become ignited and are then extinguished as they pass above us, or they may pass above and then below the earth, or there may be other causes. We may also entertain other theories to explain these movements, so long as those theories do not contradict what we observe.

The motion of the lights in the sky may be caused by the circular movement of the entire sky, or because the lights move while the heaven remains immovable. There is nothing in what we see that contradicts the theory that originally, before our world was formed, the stars and planets received, as determined necessarily by Nature, an impulse from east to west, and that now their movement continues, as the fire that burns on them naturally proceeds onward to consume more fuel.

The movements of the sun and moon between the tropics may be caused either by the shape of the heavens, as set by Nature, by necessity, long years ago, or on the resistance of the air through which they travel. The cause could occur because they burn toward the fuel which nourishes them, or because they originally received an impulse that causes them to travel in a spiral direction. The evidence we can observe does not contradict any of these different theories. We may develop other theories as well, so long as we pay due regard to what is consistent with the evidence before us, and so long as we bring each theory back to something that is similar to what we can observe in our world. Any of these theories will allow us to explain the phenomena reasonably, without disquieting ourselves with the miserable speculations of the astrologers.

The waxing and waning of the moon may also have a number of causes. These may arise from some change in the way the light of the moon is generated, or because another body comes between the earth and the moon, or for other reasons similar to phenomena we can observe here on earth. The important thing is to remember that one cannot be obstinate, and adopt, without sufficient evidence, a single and exclusive theory for the cause. Here again, where the facts are insufficient to allow us to reach a final conclusion, we must always guard against throwing ourselves into interminable speculations.

It is possible that the moon has a light of her own, or that she reflects the light of the sun. We see here on earth many examples of objects which are luminous, and many others that only reflect light. None of these celestial phenomena will cause us alarm so long as we always remember that many explanations are possible. It is essential that we always conduct our inquiries with this approach in mind, and that we do not make our decisions in any other way. Otherwise, we will be foolishly carried away into fantasies, continuously falling into one unverifiable theory after another.

The same goes for the appearance of what seems to be a face in the circle of the moon. This face may appear because of the shape of the moon, or because something obscures our vision, or for other reasons that might be capable of accounting for such an appearance. We must apply the same method here that we do with all heavenly phenomena. The moment we allow ourselves to entertain a theory that contradicts the evidence of the senses, we will thereafter find it impossible to possess perfect tranquility and happiness.

As we examine the eclipses of the sun and moon, we must compare the different theories, and remember that it is possible that many causes may at one and the same time concur in their production. The regular and periodic march of these eclipses have nothing in them that ought to surprise us, if we would only pay attention to similar phenomena which take place here on earth before our own eyes. Above all, beware the idea that a god causes these things, for we must recognize that gods are exempt from all toil, and perfectly happy. If we do not keep this in mind, we will join the crowd of men who rush to embrace vain explanations. Such men, who are not able to recognize what is really possible, fall into vain theories when they conclude that all phenomena have but a single cause, and when they reject all other explanations which are equally probable. These men adopt the most unreasonable of opinions because they fail to give priority to the observable facts, which ought always to be consulted first.

The differences in the length of nights and days may arise from the fact that the passage of the sun above the earth is more or less rapid, according to the length of the region through which it has to pass, or for some other cause similar to what we see here on earth. Those who say that only one explanation for this is possible put themselves in opposition to facts, and they lose sight of the boundaries set to human knowledge.

And then there are those who seek to predict the future from the stars. Any such predictions which happen to come true, like those predictions which some obtain from animals, arise purely by coincidence. These may happen, for example, because there is some change in the air, or from any other cause which we may find evidence to support.

Such matters as lightning and thunderbolts may be produced by a violent condensation of the winds, or by their rapid motion and conflagrations. One may give a number of explanations for these things, but we must above all be on guard against fables. This we can easily do if we faithfully follow the method we have set forth. In seeking to explain those things which we are not able to observe directly, we must always compare them to those things which we are, in fact, able to observe directly, and we must accept as possible only those theories which are supported by evidence from both.

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Hurricanes, earthquakes, wind, hail, snow, due, frost, rainbows, the halo around the moon, comets, and the regular revolutions of some stars – all of these may be explained in a number of ways if we reason in accord with observable facts. To assign one single cause to all these phenomena, when the experience of our senses suggests several causes, is folly. Such reasoning is suited only to ignorant astrologers, who covet a vain knowledge. These men assign imaginary causes to facts, because they wish to leave the care and government of the universe entirely to the gods. The assignment of one uniform and positive explanation to all these matters is foolish, and consistent only with the desire to flash prodigies in the eyes of the crowd.

The same is also true for those who seek to make forecasts by observing certain animals. Any such forecasts which happen to come to pass occur purely by chance, for there is no necessary connection between certain animals and winter. These animals do not produce winter, nor is there any god sitting in heaven, watching for the exits of these animals, and then causing winter to arrive. Such a folly as this would not occur to any being who is even moderately comfortable, much less to a god, who is possessed of perfect happiness.

Imprint all these precepts in your memory, Pythocles. If you do so, you will easily escape fables, and you will discover many other truths similar to these. Above all, apply yourself to the study of general principles of Nature, and to infinity, and to similar questions. Study closely the use of the evidence that comes from the senses, and from the anticipations, and from the feelings of pleasure and pain. Apply yourself to these, always keeping in mind the goal of happy living, toward which we prosecute all our researches.

Once you resolve these general matters in your mind, by following the example I have set forth, the answers to your particular questions will eventually become clear to you. As to those men who will not apply themselves to this study, such men will never find the truth, nor will they reach the goal of happy living, toward which all our research directs us.



And Thus Ends the Letter to Pythocles.


Peace and Safety!


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