12. It is not possible for a man to banish all fear of the essential questions of life unless he understands the nature of the universe, and unless he banishes all consideration that the fables told about the universe could be true. Therefore a man cannot enjoy full happiness, untroubled by turmoil, unless he acts to gain knowledge of the nature of things.

Alternate Translations: Bailey: A man cannot dispel his fear about the most important matters if he does not know what is the nature of the universe but suspects the truth of some mythical story. So that without natural science it is not possible to attain our pleasures unalloyed. Yonge: A man cannot dispel his fear about the most important matters if he does not know what is the nature of the universe but suspects the truth of some mythical story. So that without natural science it is not possible to attain our pleasures unalloyed

Letter to Menoeceus: Let no one delay in the study of philosophy while he is young, and when he is old, let him not become weary of the study. For no man can ever find the time unsuitable or too late to study the health of his soul. And he who asserts either that it is too soon to study philosophy, or that the hour is passed, is like a man who would say that the time has not yet come to be happy, or that it is too late to be happy. So both the young and the old must study philosophy – that as one grows old he may be young in the blessings that come from the grateful recollection of those good things that have passed, and that even in youth he may have the wisdom of age, since he will know no fear of what is to come. It is necessary for us, then, to meditate on the things which produce happiness, since if happiness is present we have everything, and when happiness is absent we do everything with a view to possess it.

Letter to Menoeceus: Meditate then, on all these things, and on those things which are related to them, both day and night, and both alone and with like-minded companions. For if you will do this, you will never be disturbed while asleep or awake by imagined fears, but you will live like a god among men. For a man who lives among immortal blessings is in no respect like a mortal being.

Cicero’s Defense of Epicurus: The great disturbing factor in man’s life is ignorance of good and evil. Mistaken ideas about these frequently rob us of our greatest pleasures, and torment us with the most cruel pains of mind. Thus we need the aid of Wisdom to rid us of our fears and unnatural desires, to root out all our errors and prejudices, and to serve as our infallible guide to the attainment of happiness. Wisdom alone can banish sorrow from our hearts and protect us from alarm and apprehension. Become a student of Wisdom, and you may live in peace and quench the glowing flames of vain desires. For the vain desires are incapable of satisfaction — they ruin not only individuals but whole families, and in fact they often shake the very foundations of the state. It is the vain desires that are the source of hatred, quarreling, strife, sedition, and war. Nor do the vain desires flaunt themselves only away from home, and turn their onslaughts solely against other people. For even when they are imprisoned within the heart of the individual man, they quarrel and fall out among themselves, and this can have no result but to render the whole of life embittered. For this reason it is only the wise man, who prunes away all the rotten growth of vanity and error, who can possibly live untroubled by sorrow and by fear, and who can live contentedly within the bounds that Nature has set.

Cicero’s Defense of Epicurus: Therefore we observe that ignorance and error reduce the whole of life to confusion. It is Wisdom alone that is able to protect us from the onslaught of the vain appetites and the menace of fears. Only wisdom is able to teach us to bear the hardships of fortune with moderation, and only wisdom is able to show us the paths that lead to calmness and to peace. Why then should we hesitate to proudly affirm that Wisdom is to be desired, not for its own sake, but for the sake of the happiness it brings? And why therefore should we hesitate to affirm that Folly is to be avoided, again not for its own sake, because of the injuries that follow in its path?”

Cicero’s Defense of Epicurus: Theoretical logic, on which your Platonic school lays such stress, Epicurus held to be of no assistance either as a guide to conduct or as an aid to thought. In contrast, he deemed Natural Philosophy to be all-important. Natural Philosophy explains to us the meaning of terms, the nature of cause and effect, and the laws of consistency and contradiction. A thorough knowledge of the facts of Nature relieves us of the burden of superstition, frees us from fear of death, and shields us against the disturbing effects of ignorance, which is often in itself a cause of terrifying fears. A knowledge of those things that Nature truly requires improves the moral character as well. It is only by firmly grasping a well-reasoned scientific study of Nature, and observing Epicurus’ Canon of truth that has fallen, as it were, from heaven, which affords us a knowledge of the universe. Only by making that Canon the test of all our judgments can we hope always to stand fast in our convictions, undeterred and unshaken by the eloquence of any man. On the other hand, without a firm understanding of the world of Nature, it is impossible to maintain the validity of the perceptions of our senses. Every mental presentation has its origin in sensation, and no knowledge or perception is possible unless the sensations are reliable, as the theory of Epicurus teaches us that they are. Those who deny the reliability of sensation and say that nothing can be known, having excluded the evidence of the senses, are unable even to make their own argument. By abolishing knowledge and science, they abolish all possibility of rational life and action. Thus Natural Philosophy supplies courage to face the fear of death; and resolution to resist the terrors of religion. Natural Philosophy provides peace of mind by removing all ignorance of the mysteries of Nature, and provides self-control, by explaining the Nature of the desires and allowing us to distinguish their different kinds. In addition, the Canon or Criterion of Knowledge which Epicurus established shows us the method by which we evaluate the evidence of the senses and discern truth from falsehood.

Letter to Pythocles: It is not good to desire what is impossible and to endeavor to articulate a uniform theory about everything. Accordingly, we should not adopt here the method which we have followed in our researches into ethics or in the solution of problems of natural philosophy. There we said, for instance, that there are no other things except matter and the void, and that the atoms are the principle elements of things, and so on. In other words, we gave a precise and simple explanation for every fact that could be conformed to what we see [and observe directly]. We cannot act in the same way with respect to the heavenly phenomena. These phenomena may arise from several different causes, and we may arrive at many different explanations on this subject that are equally agreeable with the appearances that we can observe through the senses. In regard to the stars and planets we do not have the ability to reason out new principles and to lay down absolute rules for the interpretation of Nature, because the only guide for us to follow here are the appearances themselves. Our object then that we have in view is not to set up a system of vain opinions, but rather to attain a life that is exempt from every kind of fear and turmoil. So long as we accept only those explanations of the heavenly phenomena that are conformable with the evidence we see, we are not inspired with any fears, as are those who allow that any hypothesis at all may possibly be true. But if we abandon the rule of accepting only those hypotheses that are reasonable, and we renounce the attempt to explain the heavenly phenomena by means of analogies that are founded on the evidence provided by senses, then we are conducting ourselves in complete disregard of the science of Nature in favor of falling into fables.

Lucretius De Rerum Natura Book I: When human life – before the eyes of all – lay foully prostrate upon the earth, crushed down under the weight of religion, which glowered down from heaven upon mortal men with a hideous appearance, one man – a Greek – first dared to lift up his mortal eyes and stand up face-to-face against religion. This man could not be quashed either by stories of gods or thunderbolts or even by the deafening roar of heaven. Those things only spurred on the eager courage of his soul, filling him with desire to be the first to burst the tight bars placed on Nature’s gates. The living force of his soul won the day, and on he passed, far beyond the flaming walls of the world, traveling with his mind and with his spirit the immeasurable universe. And from there he returned to us – like a conqueror – to tell us what can be, and what cannot, and on what principle and deep-set boundary mark Nature has established all things. Through this knowledge, superstition is thrown down and trampled underfoot, and by his victory we are raised equal with the stars.

Lucretius De Rerum Natura Book I: Your terror and darkness of mind must be dispelled – not by the rays of the sun and glittering shafts of day, but by the study of the law of nature.

Lucretius De Rerum Natura Book II: For even as children are terrified and dread all things in the thick darkness, thus we in the daylight fear at times things not a bit more to be dreaded than those which children shudder at in the dark and fancy to be true. Therefore this terror and darkness of mind must be dispelled, not by the rays of the sun and glittering shafts of day, but by a clear view of the law of Nature.

Lucretius De Rerum Natura Book III: So far, I have shown in what way all things have their first beginnings, of such diverse shapes, which fly spontaneously on in everlasting motion, and how all things are produced out of these. Next, my verses must clear up the nature of the mind and soul, and drive the dread of Hell headlong away, since that dread troubles the life of man from its inmost depths, and overspreads all things with the blackness of death, allowing no pleasure to be pure and unalloyed.

Lucretius De Rerum Natura Book III: And men are driven on by an unreal dread, wishing to escape and keep the gates of death far away. They amass wealth by civil bloodshed and greedily double their riches, piling up murder on murder. Such men cruelly celebrate the sad death of a brother, and hate and fear the tables of their relatives. Often, from the same fear, envy causes them to grieve, and they moan that before their very eyes another person is powerful, famous, and walks arrayed in gorgeous dignity, while they are wallowing in darkness and dirt. Some wear themselves to death for the sake of statues and a famous name. Often men dread death to such a degree that hate of life and the sight of daylight seizes them so that in their sorrow they commit suicide, quite forgetting that this fear of death was the source of their worries. Fear of death prompts some men to forsake all sense of shame, and others to burst asunder the bonds of friendship, overturning duty at its very base. Often men even betray their country and their parents in seeking to escape the realms of Hell. For even as children are flurried and dread all things in the thick darkness, thus we in the daylight fear things not a bit more to be dreaded than what children shudder at in the dark and fancy to be real. This terror and darkness of mind must be dispelled, not by the rays of the sun and glittering shafts of day, but by the study of the law of Nature.

Lucretius De Rerum Natura Book III: In truth there is no Tantalus, poor wretch, numbed by groundless terror as the story goes, fearing a huge stone hanging in the air above him. In life, however, a baseless dread of the gods terrifies men, and the falling rock they fear is the bad luck that chance brings to each one.

Vatican Saying 49: It is impossible for someone to dispel his fears about the most important matters if he does not know the Nature of the universe but still gives some credence to myths. So without the study of Nature there is no enjoyment of pure pleasure.