Introduction to Lucretius: On the Nature of Things
by M.F. Smith

Reprinted by permission of Hackett Publishing Company, from Lucretius: On the Nature of Things, Translated, with Introduction and Notes by Martin Ferguson Smith, Copyright © 1969 Martin Ferguson Smith and  Copyright © 2001 Hackett Publishing Company, Inc.  All rights reserved.  Unauthorized copying strictly prohibited.

Numerical references are always, unless otherwise indicated, to the text of Lucretius.

1. Lucretius

Of all the great Latin writers, we know least about Titus Lucretius Carus, author of the philosophical poem On the Nature of Things (De Rerum Natura). He does not talk about himself in the way that his contemporary Catullus does, and information from other sources is meager and unreliable. St. Jerome, writing more than four hundred years after Lucretius’ death, makes the sensational statement that the poet went mad in consequence of drinking a love potion, wrote in the intervals of his insanity, and committed suicide. Since earlier writers show no knowledge of this story,2 it can confidently be dismissed as a fabrication, probably designed to undermine the credibility of the materialistic philosophy that Lucretius expounds. The story is used by Tennyson in his poem Lucretius and by the contemporary novelist Luca Canali,3 which is fine; unfortunately, however, it is not always confined to the realm of fiction: under its influence some critics have detected in Lucretius’ work signs of morbid pessimism and even mental unbalance and then have used their “discoveries” as confirmation of what St. Jerome says—a circular procedure that is completely out of order. The correct approach is to consign Jerome’s statement to the wastepaper basket and to approach On the Nature of Things with an unprejudiced mind.

Lucretius was born at the beginning of the first century b.c., perhaps in 99 b.c., and it is most probable that he died in 55 b.c.4 If we assume that the dates 99–55 are correct, he was born when Cicero was aged seven and Julius Caesar was a toddler; and when he died, Virgil and Horace were aged fifteen and nine or ten respectively. Catullus probably died in 54 b.c.

We know nothing of Lucretius’ family, but, whether he was highborn or of humbler origin, it is evident that he received an excellent education: a master not only of Latin, but also of Greek, he possessed a wide knowledge of the literature of both languages; and his partiality for legal and political metaphors suggests that he may have been prepared for a forensic or political career.

He was familiar with the city and may have spent much of his life in Rome. He appears to have witnessed military exercises on the Campus Martius (2.40–43, 323–332); he had attended horse races (2.263–265; 4.990) and theatrical performances (2.416–417; 4.75–83, 978–983; 6.109–110). His vivid description of the man who leaves his fine mansion in the city out of boredom, jumps into the ancient equivalent of a fast car, dashes out to his country villa as though on his way to save a house on fire and, as soon as he has arrived, yawns and either goes to sleep or returns to the city (3.1060–1067), must be based on his own experience of the restless and unsatisfactory life led by some wealthy Romans.

It is clear, however, that not all his time was spent in the city. Numerous passages in his poem show his familiarity with the countryside, woods and forests, mountains, rivers, and streams. He has an extraordinary sympathy with nature and possesses the keen powers of observation of an artist. Witness his vivid picture in the opening lines of the poem (1.1–20) of the effect of spring on climate, flowers, pastures, sea, sky, winds, birds, wild animals, and cattle. Witness too his descriptions of animals in the fields: the cow searching vainly for her lost calf (2.352– 366); the flock of sheep and lambs moving on the green hillside, but appearing only as a motionless white blur when viewed from the distance (2.317–322); and the newborn calves and lambs, “intoxicated” with milk, frisking on unsteady legs in the tender grass (1.259–261). The probability is that he owned a villa in the country and spent as much time as possible there.

A line in Book 4 (1277) has been taken, perhaps rightly, to imply that he was a married man. Several passages in the poem suggest that he was fond of children, but of course do not prove that he had any of his own. The celebrated attack on sexual love (4.1058–1191), which has sometimes been thought to reflect his own unhappy experience of the opposite sex (compare the story of the love potion), is in line with the Epicurean view that while it is all right to satisfy sexual desire, provided that this does not cause one physical or mental disturbance, the passion of love is disturbing and destructive and therefore to be avoided.

The times through which Lucretius lived were dominated by intense social and political unrest and punctuated with outbreaks of revolution and war. The second decade of the first century b.c. was a period of civil war and bloodshed; and if one takes 99 as the year of his birth, he would have been seventeen when thousands of Samnites were butchered at the Colline Gate near the Quirinal Hill; twenty-six when Spartacus led the great revolt of slaves, six thousand of whom were to be crucified along the Appian Way; and thirty-six at the time of Catiline’s conspiracy. It is hardly surprising that one who, as his poem shows, was so sensitive to human suffering, should have become an Epicurean, a follower of a philosopher who taught that one should take no part in the struggle for wealth and power, who attached the greatest importance to friendship, and who offered his adherents tranquillity of mind.

The only friend or acquaintance whom Lucretius mentions is the addressee of his poem, Memmius (see section 2, below). But it is fair to assume that he also knew Catullus and Catullus’ poet-friend Helvius Cinna, whom Memmius patronized. There are verbal parallelisms between Lucretius’ poem and Catullus 64 (Peleus and Thetis), which seem too numerous to be accidental, but we cannot be sure who was the imitator and who the imitated. If Lucretius knew Catullus, he may also have encountered some of those with whom Catullus associated, including Clodia, whose stormy affair with Catullus (exactly the sort of relationship against which Lucretius warns his readers in Book 4) is revealed in Catullus’ poetry, where she is called Lesbia.

Jerome states that after Lucretius’ death Cicero “emended” (emendavit) his work. The Latin verb probably refers here, as elsewhere, to the making of essential corrections to a work in readiness for publication—the sort of corrections that nowadays a proofreader is expected to make. Jerome’s statement is less likely to be of trustworthy origin than to be a guess based on the information, given to us by Cicero himself (see section 2, below), that he had read On the Nature of Things. Although Cicero thought well of Lucretius’ poetry, as we shall see, and wrote poetry himself, his dislike of Epicureanism makes it seem improbable that he would have prepared On the Nature of Things for publication. Someone who is more likely, one would suppose, to have helped Lucretius’ work reach the public is Cicero’s closest friend Atticus, who not only was an Epicurean, albeit a less than fully committed one, but also owned a well-organized publishing business. Perhaps it was his copyists who made the first copies of On the Nature of Things.

One naturally wonders whether Lucretius knew other famous contemporaries. Did he meet the Epicurean teachers Siro and Philodemus, the former of whom is reported to have taught Virgil, the latter of whom, a writer of poems as well as of philosophical treatises, made Virgil the coaddressee of one of his books?5 Was he acquainted with Amafinius,6 Catius, and Rabirius, who wrote in Latin (unlike Philodemus, who used Greek) and did much to popularize Epicurean ideas in Italy with their prose works? Did he know Julius Caesar, who seems to have had some sympathy with Epicureanism, or Caesar’s destined assassin Cassius, who certainly counted himself an adherent of the school, though, like many Roman Epicureans, he was not obedient to Epicurus’ advice to keep out of politics and public life? We can only guess.

2. On the Nature of Things

On the Nature of Things is Lucretius’ only extant work; and, so far as we know, it is the only work that he produced, though it is inconceivable that he had not tried his hand at poetry before he embarked on the composition of his masterpiece, a poem divided into six books and containing about seven thousand five hundred lines.7

The meter of the poem is the dactylic hexameter. This is the meter used by Greek epic and didactic poets, including Homer and Hesiod, the philosophers Parmenides and Empedocles, and the Hellenistic poets Apollonius of Rhodes, Aratus, and Nicander. The first to employ the meter in Latin was Ennius (239–169 b.c.), author of the epic Annals, and he was followed by later writers of Latin epic and didactic.

Although On the Nature of Things has a didactic character and purpose, it is also an epic—an epic whose theme is the universe, the world, nature, human beings, the soul, death, and the gods. It is to be noted that it is the Muse of epic poetry, Calliope, whom Lucretius invokes at 6.92–95. Because the poem is both epic and didactic, its language ranges from the lofty to the conversational: often, particularly when Lucretius is introducing a new topic, he addresses Memmius much as a teacher addresses a pupil, sometimes calling quite sharply for his attention.

The brilliant poetical qualities of Lucretius’ work result partly from his own imagination, observation, experience, reflection, and peculiar genius, partly from his knowledge and subtle exploitation of a wide range of Greek and Latin literary sources and from his mastery of rhetorical technique. Not all the influences on Lucretius’ poetry can be mentioned here. They include the only three poets8 range of Greek and Latin literary sources and from his mastery of rhetorical technique. Not all the influences on Lucretius’ poetry can be mentioned here. They include the only three poets8 named by him—Homer, Empedocles, and Ennius, all of whom he deeply admired (see 1.117–119, 124, 716–737; 3.1037–1038). His debt to Ennius and other early Latin poets is significant: he employs archaic words and forms, and he is fond of compound adjectives, assonance, and alliteration—all prominent features of the work of Ennius and company. But, while his poetry retains the vigor of theirs, it is far more polished, and it is only within the last few decades that scholars have properly noticed and explored his not inconsiderable debt to Hellenistic poetry—poetry characterized by, among other things, learning and refinement.9 One of the prominent manifestations of his poetic art is the extraordinary richness and subtlety of the imagery that he employs.10 Another remarkable feature of his writing is the way in which, instead of banishing mythology from his work, as one might expect an Epicurean poet to have done, he skillfully exploits it for his poetical and philosophical purposes:11 see, for example, the opening passage of the poem (1.1–43).

Lucretius probably embarked on the composition of On the Nature of Things in or about 59: lines in the opening passage (1.41–43) seemingly allude to Memmius’ praetorship of 58. When he died, probably in 55, his work, though almost finished, still lacked final revision. Some of the chief indications of lack of revision may be mentioned: there are alternative introductory passages in Book 4 (see note on 4.45–53); at 5.155 there is a promise of a proof that is not provided; and there are places where the transition from one passage to another is very abrupt: see, for example, 5.235, where the argument of 5.91–109 is resumed as if the intervening refutation of belief in the divine origin and character of the world in 5.110–234 were not there. Repetitions of passages, which are not uncommon in the poem, have sometimes been regarded as another sign of lack of revision, but probably Lucretius intended to retain most, if not all, of the repeated passages: repetition is an effective way of getting important facts to stick in the reader’s mind; and a certain amount of repetition is almost inevitable in a scientific work in which the author cannot refer the reader to earlier passages by means of footnotes.  Whether the actual ending of On the Nature of Things is (as I believe) the intended ending, or whether Lucretius did not live to add the concluding passage that he had planned, is not agreed, but we can at least be sure that he had no intention of writing more than six books: he makes clear at 6.93–94 that he is working on the last book.

The philosophy that Lucretius expounds in On the Nature of Things is not his own, though he believes in it as passionately as if it were.  He faithfully reproduces the doctrines of Epicurus.  He has sometimes been criticized for making an unfortunate choice of subject.  After all, as he himself was well aware (1.136-139), the presentation of Greek philosophy and science in Latin poetry was no easy task.  But he did not choose his theme.  It was not a case of wanting to write a poem, looking about for a suitable subject, and eventually deciding upon Epicureanism.  Epicureanism had to be his theme.  That this is so becomes obvious if we consider his relation to Epicurus, about which he tells us so much.  He devotes four magnificent passages, full of emotion, to heartfelt praise of his master (1.62-79; 3.1-30; 5.1-54; 6.1-42).12 He regards Epicurus as the spiritual and moral savior of himself and of humanity.  Epicurus is to him as Jesus is to a Christian.  He has complete faith in him and regards his sayings as infallible.  He claims to follow him not in rivalry, but out of love for him.  He calls him “father”; he even hails him as a god, not because he really believes him to be divine, but because it is the only description that is appropriate to one who possessed seemingly superhuman qualities and who enabled human beings to create a heaven on earth through the attainment of the perfect peace of mind in which perfect happiness consists.  Epicurus had discovered the truth and the whole truth, and Lucretius endeavors to communicate that truth as accurately, attractively, and persuasively as he can.

The Epicurean school was very much a “society of friends.” Epicurus thought that “of all the contributions that wisdom makes to the blessedness of the complete life, much the most important is the possession of friendship” (Principal Doctrines 27) and that “the chief concerns of the right-minded person are wisdom and friendship, of which the former is a mortal benefit, the latter an immortal one” (Vatican Sayings 78). In these pronouncements he is referring to something more than ordinary friendship: he means the friendship, fellowship, and love of persons who share the same ideals and the same philosophy—Epicureanism, of course. An Epicurean could find philosophical friends both by joining a circle of adherents and by making new converts. The making of converts was encouraged, and the recommended method of conversion was by personal contact: just as a doctor treats individual patients, so the philosopher treats individually, if that is possible, those who are morally sick.13 Obviously the situation is different when Epicureans, wanting to make their master’s efficacious remedies available to those not known to them, including those not yet born, communicate them in writing, but it is noticeable that even Epicurean writers, though they want to reach as many readers as possible, frequently address the public through the medium of an address to an individual or to a small group of persons. Epicurus himself does this, and so does Lucretius.

Whether Memmius, to whom On the Nature of Things is addressed, was Lucretius’ patron or not (I doubt if he was), he is not a mere dedicatee, for Lucretius informs him that the inspiration of the poem is “the hope of gaining the pleasure of your delightful friendship” (1.140-145) – in other words, the hope of converting him to Epicureanism.  There can be no doubt that he wants his message to benefit anyone who would read his work, but he speaks to this wider audience, through the medium of his address to Memmius.

Gaius Memmius, a member of a senatorial family and the husband of Sulla’s daughter Fausta until he divorced her in 55, had been tribune, perhaps in 62;14 he became praetor in 58 and governor of the province of Bithynia in northwest Asia Minor in 57; in 54 he stood for the consulship but was unsuccessful, and in 52, after being found guilty of using bribery in the elections of 54, went into exile in Greece, where, as we shall see shortly, he showed himself to be no friend of the Epicureans. He is said by Cicero, who was on friendly terms with him, to have been accomplished in Greek literature, but scornful of Latin, and to have been a talented orator, but lazy (Brutus 247). He may have been a lazy orator, but he was more energetic in another direction: his adultery with the wives of two of his political enemies, the brothers Marcus and Lucius Lucullus, is reported by Cicero in a letter dated 20 January 60 (Letters to Atticus 1.18.3). The erotic poetry that he wrote does not survive: according to Ovid, its language left little to the imagination (Tristia 2.433–434), but this does not mean that it was without literary merit, and he showed good taste by patronizing Catullus and Helvius Cinna.

Scholars have often expressed surprise that Lucretius chose to address his Epicurean poem to a man of such imperfect character and un-Epicurean behavior, and some have even doubted the identification of Lucretius’ Memmius with Gaius Memmius. But there is no need for either surprise or doubt. Given that Lucretius’ purpose is to enlighten the unenlightened, it would have been very odd if he had not chosen to address someone who was in need of enlightenment and reform. Although he tactfully describes Memmius as a man of good character and good reputation (1.26–27, 140; 3.420; 5.8), he was no doubt well aware of his weaknesses and hoped that he would heed his warnings against the dangers of, for example, ambition and sexual passion. The fact is that Memmius’ imperfections, together with his prominent position in public life, well qualified him to be the addressee of On the Nature of Things.  There was also something else, something very important, that so qualified him—his interest in poetry.

When Lucretius decided to expound the Epicurean system in a poem, he was taking a bold, indeed unprecedented, step: no one had done it before in Greek or Latin. In the fifth century b.c. Parmenides and Empedocles had written philosophical poems, and Lucretius, who, despite his disagreement with Empedocles’ views, warmly praises him, undoubtedly regarded him as his chief model as a philosopher-poet.15  Epicurus, however, had discouraged the writing of poetry and, though he could write elegant prose if he wished, usually adopted an arid style, apparently regarding literary adornment as an obstacle, rather than as an aid, to clear understanding. Lucretius is well aware that he is a pioneer, and is extremely proud of the fact (1.921–934; 4.1–9; 5.336–337). He is also fully conscious of the formidable nature of his task: he refers to the difficulty of “illuminating the obscure discoveries of the Greeks in Latin verse” (1.136–137); and he draws attention to the inadequacy of his native language (1.139, 832; 3.260), which means that he has to invent many new terms (1.138).16 It is evident that he overcame these difficulties not only by his genius, but also by sheer hard work: he describes his verses as “the product of long research and the fruit of joyful labor” (3.419), and confesses that he spends “the still calm of the night” working on his poem(1.142–145), reminding one of Robert Bridges’s would be poet “o’er his lamp-lit desk in solitude.”

Why did he choose to expound his philosophy in verse rather than in prose? The obvious answer is that he was a natural poet who knew that he could put across his message more effectively in verse. But it is clear too that he believed that a poetic exposition of Epicureanism was more likely to attract and persuade Memmius and no doubt other cultured Romans. In a famous and important passage (1.936–950, repeated at 4.11–25) he explains that, just as doctors trick children into drinking unpleasant-tasting, but beneficial, medicine by first coating the rim of the cup with honey, so he has chosen to coat Epicurean philosophy with the sweet honey of the Muses in the hope of holding Memmius’ attention and enabling him to learn the truth about nature. To what extent it was a question of his instinctively knowing that he must write a poem because his own genius demanded it, and to what extent he deliberately chose verse to suit Memmius and others who had found Epicureanism, as usually presented, off-putting, we cannot be sure. What is certain is that the situation in which he found himself was a fortunate one, because the need to write in verse in order to be most effective as an exponent of philosophy enabled him at the same time to satisfy his poetic aspirations. His philosophical purpose, the enlightenment of Memmius, is both the inspiration and the justification of the poem.

Does the fact that Lucretius, on his own admission, uses his poetic art to sugar the somewhat bitter pill of his philosophy mean that he is a great poet in spite of his Epicureanism rather than because of it? Does it mean that, from a poetic point of view, it would have been better if he had not been an Epicurean and thus had been free to compose a poem on a theme that lent itself more readily to poetic treatment than an abstruse philosophical system? The Romantics answered yes to these questions: Shelley complains that “Lucretius had limed the wings of his swift spirit in the dregs of the sensible world”; and Byron comments: “If Lucretius had not been spoiled by the Epicurean system, we should have had a far superior poem to any now in existence.” But these criticisms are misguided. As I have written elsewhere: “Certainly it must be admitted that [Lucretius] was a natural poet, and that, if he had taken a more traditional theme, the result would have been an artistic poem. But [On the Nature of Things] is one of the world’s greatest poems not because it is merely artistic, but because it is also full of passion, fervour, and emotion: the poet is inspired with a deep sense of missionary purpose and puts all his heart and soul, as well as all his intellectual power, into his writing, and that is largely why his work still grips our attention, still throbs with life and excitement. If he had not been an Epicurean, this inspiration would have been lacking.”17 As I have pointed out above, On the Nature of Things, though often labeled a didactic poem, is also an epic of the universe and of everything in it, including human beings. Even the ultimate particles of matter, the imperceptible atoms, inspire fine poetry, since Lucretius demonstrates their existence and illustrates their properties and movements by introducing many superbly conceived and brilliantly described analogies from the perceptible world. Coleridge’s remark to Wordsworth that “whatever in Lucretius is poetry is not philosophical, whatever is philosophical is not poetry,” though valued by teachers as a convenient topic for essays and tutorials, could not be more wrong: in On the Nature of Things philosophy and poetry are inextricably intertwined.

The merits of Lucretius’ poetry were acknowledged at once, and he exercised a considerable influence on his immediate successors. Cicero, writing to his brother (Letters to Quintus 2.9) on 10 or 11 February 54 b.c., comments: “The poetry of Lucretius is, as you say in your letter, rich in brilliant genius, yet highly artistic.” Virgil owed a vast poetic debt to Lucretius not only in his pastoral Eclogues and didactic Georgics, but also in his epic Aeneid, and it is undoubtedly Lucretius who is at the front of his mind when he writes: “Blessed is he who has succeeded in finding out the causes of things and has trampled underfoot all fears and inexorable fate and the roar of greedy Acheron”18 (Georgics 2.490–492).  Horace, who toyed with Epicureanism, was influenced by Lucretius, though much less deeply than Virgil was, in early life. Ovid admired On the Nature of Things, prophesying that “the verses of sublime Lucretius are destined to perish only when a single day will consign the world to destruction” (Amores 1.15.23–24). The Stoic Manilius, who wrote an astrological poem early in the first century a.d., though he disagreed strongly with Lucretius’ Epicurean views, was influenced by him.

So the influence of Lucretius’ poetry is not in doubt. But what of his philosophy? Did he succeed in making any converts to Epicureanism? Certainly he failed to convert Memmius. He must have hoped to rescue him from the stormy seas of political life, and he had warned him about the harmful consequences of ambition (see especially 3.59–78, 995–1002; 5.1120–1135); and yet Memmius not only stood for the consulship of 54, but showed himself to be so unscrupulously ambitious that, as we have seen, he used bribery. Moreover, as an exile in Athens, he obtained permission from the city’s authorities to build on the remains of Epicurus’ house, and thus distressed and angered the Epicureans; he appears to have gone out of his way to annoy them. There is a simple explanation for his behavior. If one assumes, as one reasonably may, that On the Nature of Things had been recently published when the Cicero brothers exchanged opinions on Lucretius’ poetry early in 54, its publication can be placed late in 55. Soon afterward Memmius was exiled in consequence of a vice against which Lucretius had warned him. If Lucretius had lived to witness Memmius’ disgrace, he might well have remarked, “Well, what did I tell you?” Memmius naturally felt that he had been made to look foolish in the eyes of the public and took his revenge on the Epicureans in a rather childish way. I am speculating of course, but such an act of vindictiveness would not have been out of character for a man who was probably motivated partly, if not mainly, by spite against his political opponents when he bedded their wives. Although Lucretius did not succeed in converting Memmius, it is rash to assume, as some have done, that his missionary effort was a total failure. There is evidence that he was not only admired as a poet, but also taken seriously as an exponent of Epicureanism.19 Virgil was influenced by his thought as well as by his poetry, and it is tempting to suppose that it was a reading of On the Nature of Things that persuaded him to study under the Epicurean philosopher Siro in Naples. It would be surprising if many did not derive comfort from Lucretius’ philosophy in the dark days of the civil wars (49–31 b.c.) and under Nero (a.d. 54–68) and Domitian (a.d. 81–96), who, after beginning their reigns in good style, dealt ruthlessly with their opponents or presumed opponents. Even when Lucretius’ poem did not convince its readers, it must have contributed greatly to their understanding of Epicurean philosophy. The Christian writer Arnobius, writing about a.d. 300, seems to have derived much of his information about Epicureanism from On the Nature of Things, and the strong attacks that his pupil Lactantius makes on Lucretius suggest that he regarded him as philosophically significant.

Although Lucretius is not an original philosopher, he deserves to be reckoned a philosopher in that, as Cyril Bailey observes, he has “a firm and clear grasp of a great world-system, which he expounds with a marvellous vividness and completeness.” Whether he relied on a single work of Epicurus, as has recently been argued (see section 3, below), or used several of his master’s works, his presentation of Epicureanism is, to a significant degree, his own, and not only because it is in brilliant Latin poetry rather than in dull Greek prose: it is evident that it results from the extraction, condensation or expansion, adaptation and rearrangement of material that he found in Epicurus’ work, with the addition of material drawn from non-Epicurean sources and from his own experience. All the material is carefully chosen and organized to suit his missionary purpose. He follows Epicurus faithfully, but not blindly: because he lived more than two centuries after his master and was not a Greek, but a Roman, he takes good care to ensure that what is, after all, not a dead philosophical system, but a living faith, is fully relevant to the needs of Memmius and his contemporaries. He puts Epicureanism into an unmistakably Roman setting.

3. Epicurus and Epicureanism

Epicurus was born on the island of Samos, just off the west coast of Asia Minor, in 341 b.c. His parents were Athenians. His early education was presumably provided by his father, who was a schoolmaster. He is said to have first become interested in philosophy at the age of fourteen. After military service in Athens (323–321), he rejoined his family in the Ionian city of Colophon, near Ephesus, where they had resettled. In nearby Teos he studied under Nausiphanes, a follower of the philosopher Democritus (c.460–c.370), who had developed the atomic theory invented by Leucippus about 440. Epicurus adopted and modified the atomic theory, and it is natural to assume that it was Nausiphanes who introduced him to it.

In 311 Epicurus moved north to Mytilene on the island of Lesbos and began to teach in public. But he was apparently regarded as a subversive influence and had to leave in a hurry. It may have been this experience that persuaded him of the wisdom of “living unnoticed”; at any rate his first attempt to teach in public seems also to have been his last. He made some converts in Mytilene, including Hermarchus, who was to succeed him as head of the Epicurean school, and he made more converts in Lampsacus, a city on the Asiatic shore of the Hellespont, where he sought refuge. One of his converts in Lampsacus was Metrodorus, the most important member of the school after himself, who predeceased him. Another was Colotes, who, on hearing him speak, fell down before him and hailed him as a god. Colotes’ reaction is indicative of Epicurus’ charisma. Indeed, if he had not been capable of exerting a powerful influence on the minds of others, he would not have succeeded in founding a school that was to be an important presence in the ancient world for six centuries—for three centuries before Christ and for three after him.  His followers were noted for their loyalty and devotion to him, and he was revered and loved not only during his lifetime, but also long after his death. We have already seen how Lucretius regarded him. Epicurus encouraged this reverence for himself, because “the veneration of the wise man is a great benefit to those who venerate him” (Vatican Sayings 32).

In 307/306 b.c. Epicurus moved to Athens and purchased a house with a small garden. His school was often to be called the Garden, while the school founded in Athens at about the same time by Zeno of Citium was called the school of the Porch—the Stoic school.20 Epicurus taught in Athens for thirty-six years until his death in 270. During this period he seems never to have taught in public, and he left the city only occasionally to visit friends in Asia Minor.21 He lived a life of great simplicity with his pupils, who included women and slaves. In his last years he was afflicted with strangury (difficult and painful passage of urine), probably caused by enlargement of the prostate. He bore his illness with the utmost cheerfulness and, when on the verge of death and in great physical pain, wrote a letter in which he refers to his great happiness and joy.

Epicurus was a voluminous writer, but only a small percentage of what he wrote has survived. Thanks to the third-century a.d. writer Diogenes Laertius, who quotes them, we have three letters that Epicurus wrote to pupils—Letter to Herodotus (on physics), Letter to Pythocles22 (on astronomy and meteorology), Letter to Menoeceus (on ethics)—and a collection of forty moral sayings known as the Principal Doctrines (Kyriai Doxai). We also have eighty maxims (not all of them new and not all of them written by Epicurus himself ), which, because they were discovered (in 1888) in a manuscript in the Vatican Library, are known as the Vatican Sayings. Epicurus’ other writings either are lost or survive only in fragments. The most abundant source of fragments has been the volcanic ash of Herculaneum near Naples. Herculaneum, like Pompeii, was overwhelmed by the eruption of Vesuvius in a.d. 79, and in the middle of the eighteenth century excavation of a fine villa, the so-called Villa of the Papyri, brought to light the charred remains of an Epicurean library. The villa is undoubtedly that occupied by the first-century b.c. Epicurean teacher and writer Philodemus. Some of the papyrus texts are so seriously carbonized that little or nothing can be read, but others are legible or partly legible. They include not only works by Philodemus himself and several other followers of Epicurus,23 but also significant fragments of Epicurus’ own chief work, On Nature (Peri Physeōs), which was in thirty-seven books, each book representing an installment of a lecture course.

Epicurus was a voluminous writer, but only a small percentage of what he wrote has survived.  Thanks to the third-century A.D. writer Diogenes Laertius, who quotes them, we have three letters Epicurus wrote to pupils – Letter to Herodotus (On Physics), Letter to Pythocles22 (on astronomy and meteorology), and Letter to Menoeceus (on ethics) – and a collection of forty moral sayings known as The Principal Doctrines (Kyriai Doxai).  We also have eighty maxims (not all of them new and not all of them written by Epicurus himself), which, because they were discovered (in 1888) in a manuscript in the Vatican Library, are known as the Vatican Sayings.  Epicurus’ other writings either are lost or survive only in fragments.  The most abundant source of fragments has been the volcanic ash of Herculaneum near Naples.  Herculaneum, like Pompeii, was overwhelmed by the eruption of Vesuvius in a.d. 79, and in the middle of the eighteenth century excavation of a fine villa, the so-called Villa of the Papyri, brought to light the charred remains of an Epicurean library.  The villa is undoubtedly that occupied by the first-century B.C. Epicurean teacher and writer Philodemus.  Some of the papyrus texts are so seriously carbonized that little or nothing can be read, but others are legible or partly legible.  They include not only works by Philodemus himself and several other followers of Epicurus,23 but also significant fragments of Epicurus’ own chief work, On Nature (Peri Physeōs), which was in thirty-seven books, each book representing an installment of a lecture course.

Our most important sources for Epicureanism, in addition to those just mentioned, are Lucretius, Cicero, Plutarch, and Diogenes of Oinoanda.  Lucretius gives us our fullest account of Epicurean physics. Cicero and Plutarch, though hostile to Epicureanism, provide much information, especially on ethics and, in the case of Cicero, on theology as well.  Diogenes of Oinoanda, like Lucretius, was a devoted follower of Epicurus.  It was probably in the first half of the second century a.d. that Oinoanda, a small city in the mountains of Lycia in southwest Asia Minor, received a remarkable gift from Diogenes, who must have been wealthy and locally influential. The gift was a massive Greek inscription, carved on the limestone wall of a stoa or colonnade. Diogenes explains that he has “reached the sunset of life” and that, before he dies, he wants to advertise the benefits of Epicurean philosophy with the intention of bringing moral salvation not only to his contemporaries, but also to generations to come (“for they belong to us, though they are still unborn”), and not only to the people of Oinoanda, but also to foreigners—or rather to “those who are called foreigners, though they are not really so, for . . . the whole compass of this world gives all people a single country . . . and a single home.” In accomplishment of his philanthropic and cosmopolitan mission, he sets out Epicurus’ teachings on physics, epistemology, and ethics in writings that may have contained about 25,000 words and filled about 260 square meters of wall space. The inscription is eloquent proof of the continuing existence of Epicureanism as a missionary philosophy whose adherents regarded it as the saving truth; moreover, it is a valuable addition to our sources: Diogenes’ own exposition of Epicurus’ philosophy is informative and reliable, and there is the bonus that he quotes some maxims and letters written by his master. He was unknown until late in the nineteenth century, when French and Austrian epigraphists found 88 pieces of the inscription. Since 1968, when I started a long series of British investigations at Oinoanda, another 135 fragments have been brought to light, but no more than a third of the complete work has been recovered so far.

The question of which work or works of Epicurus Lucretius used in writing On the Nature of Things has been much discussed. The obvious difficulty facing those who try to answer it is the loss of so much of what Epicurus wrote, but our state of knowledge about his writings, and especially about On Nature, is by no means static. Much progress with the decipherment, restoration, and interpretation of the papyrus texts from Herculaneum has been made in recent decades and indeed recent years, and David Sedley, who himself has made an outstanding contribution to this work, now argues that Lucretius’ only Epicurean source for “the physical exposition in the main body of all six books” (not, it is to be noted, for all the material in the poem) was On Nature, especially the first fifteen of its thirty-seven books.24 He is careful to stress that he is only talking about “the bare bones of the exposition,” and he gives full credit to Lucretius for the original way in which he handled the material, rearranging it, elaborating it, illustrating it, and of course treating it poetically. Although Sedley probably goes too far in claiming that On Nature was Lucretius’ only source in his exposition of Epicurean physics, he certainly succeeds in showing that it was his main source. It is to be noted that Lucretius’ title translates that of his master’s chief work, though it is almost certainly also meant to recall Empedocles’ poem On Nature.

Early Greek philosophers, from Thales at the beginning of the sixth century b.c. down to the second half of the fifth century, had been mainly concerned with the physical nature of the universe. They are often called the Presocratics, a name that implies that Socrates (469–399) was the introducer of a new kind of philosophy—moral philosophy. Socrates was indeed the first Greek thinker to devote himself to the systematic exploration of moral issues, though the change of interest from physical phenomena to human problems began with the independent teachers known as the sophists, some of whom, including Protagoras and Gorgias, were senior contemporaries of Socrates. After Socrates the main focus of philosophy was on ethics, though by no means all Postsocratics followed him in having no interest in natural science. The fourth century b.c. was dominated, philosophically, by the giant figures of Plato (c.428–347), founder of the Academy, and Plato’s pupil Aristotle (384–322), founder of the Lyceum. The philosophers who followed them could not fail to take account of their views, as well as those of Socrates, even when they reacted against them rather than adopted them. So it was with Epicurus, who was born six years after Plato’s death and was doing his military service in Athens when Aristotle died. His primary concern, like that of Socrates, Plato, and Aristotle, was with moral philosophy, though he had his own ideas about it and, as we shall soon see, natural science had an essential, though subordinate, part to play in his system.

Formulating his ideas at a time when Athens had ceased to be a great power and the Greek city-states, as a result of the Macedonian conquests, had lost much of their political autonomy, Epicurus offered individuals a different sort of independence—moral independence. Defining philosophy as “an activity, attempting by means of discussion and reasoning, to make life happy,” he believed that happiness is gained through the achievement of moral self-sufficiency (autarkeia) and freedom from disturbance (ataraxia).

The main obstacles to the goal of tranquillity of mind are our unnecessary fears and desires, and the only way to eliminate these is to study natural science. The most serious disturbances of all are fear of death, including fear of punishment after death, and fear of the gods. Scientific inquiry removes fear of death by showing that the mind and spirit are material and mortal, so that they cannot live on after we die: as Epicurus neatly and logically puts it: “Death . . . is nothing to us: when we exist, death is not present; and when death is present, we do not exist. Consequently it does not concern either the living or the dead, since for the living it is non-existent and the dead no longer exist” (Letter to Menoeceus 125). As for fear of the gods, that disappears when scientific investigation proves that the world was formed by a fortuitous concourse of atoms, that the gods live outside the world and have no inclination or power to intervene in its affairs, and that irregular phenomena such as lightning, thunder, volcanic eruptions, and earthquakes have natural causes and are not manifestations of divine anger.  Every Epicurean would have agreed with Katisha in the Mikado when she sings:

But to him who’s scientific
There’s nothing that’s terrific
In the falling of a flight of thunderbolts!

So the study of natural science is the necessary means whereby the ethical end is attained. And that is its only justification: Epicurus is not interested in scientific knowledge for its own sake, as is clear from his statement that “if we were not disturbed by our suspicions concerning celestial phenomena, and by our fear that death concerns us, and also by our failure to understand the limits of pains and desires, we should have no need of natural science” (Principal Doctrines 11). Lucretius’ attitude is precisely the same as his master’s: all the scientific information in his poem is presented with the aim of removing the disturbances, especially fear of death and fear of the gods, that prevent the attainment of tranquillity of mind. It is very important for the reader of On the Nature of Things to bear this in mind all the time, particularly since the content of the work is predominantly scientific and no systematic exposition of Epicurean ethics is provided.25  Epicurus despised philosophers who do not make it their business to improve people’s moral condition: “Vain is the word of a philosopher by whom no human suffering is cured. For just as medicine is of no use if it fails to banish the diseases of the body, so philosophy is of no use if it fails to banish the suffering of the mind” (Usener fr. 221). It is evident that he would have condemned the majority of modern philosophers and scientists.

As Diogenes Laertius (10.30) tells us, the Epicurean system “is divided into three parts—canonic, physics, and ethics,” though he adds that the Epicureans “usually merge the canonic with the physics.”

The canonic26 consists of Epicurus’ rules of investigation, his epistemology.  It is understandable that it was often not treated separately from physics, because the two are interlinked and interdependent.

According to the canonic, there are three criteria of truth. The fundamental criterion is sensation (1.422–425). In cases where sensation seems to deceive us, as when a square tower viewed from a distance appears to be round (4.353–363) or a straight oar submerged in water appears to be bent (4.436–442), the fault lies not with the senses, but with the mind, which wrongly interprets the information received by the senses (4.379–386, 462–468). The mechanics of sensation belong to the sphere of physics, and we shall see that sight, hearing, and smell are accounted for by a theory of emanations. The sense organs faithfully record the emanations that they receive, and if, for example, an image of a distant tower is already distorted when it reaches our eyes, they are not to be blamed any more than a camera is to be blamed if it records an already distorted image. It is when we interpret sense impressions that mistakes can arise. When we are investigating things, the aim is to obtain, wherever possible, a near, clear view of them. If we obtain such a view of a round-looking tower, we can be sure that it is indeed round. But if we have a distant view of a round-looking tower, the proper procedure is not to assume that it is round, but to suspend judgment until we can go near and obtain either “confirmation” or “nonconfirmation” of our sense impression of the distant tower. In the case of celestial phenomena and certain terrestrial phenomena such as volcanic eruptions and earthquakes a near, clear view is not possible. However, in investigating such phenomena we must still be guided by sensation. Taking phenomena of our immediate experience as “signs” and making use of analogy, we may be able to make inferences about their nature and causes, though these inferences cannot usually be confirmed when we test them against the evidence of sensation: if the result of a test is not “contradiction,” it may at best be “noncontradiction”; and if, as quite often happens, several theories pass the negative test of noncontradiction, all of them must be considered possible. This plurality-of-causes procedure was justified not only on the ground that suspension of judgment is necessary when one cannot determine which explanation of a phenomenon in our world is the correct one, but also on the ground that explanations that are not valid in our world may well be valid in other worlds. There is the further point that, since Epicurus was interested only in scientific knowledge that helps us to achieve the moral goal of tranquillity of mind, it did not bother him if he could not identify the precise cause of a particular phenomenon, so long as he could show that the phenomenon was natural and not supernatural. Lucretius, in his explanations of celestial and terrestrial phenomena in Books 5 and 6, frequently suggests several possible causes, and in each book he justifies this procedure (5.526–533; 6.703–711).27

Sensation by itself is irrational and incapable of memory, but the repeated reception of sense impressions creates in the mind general conceptions of all classes of things. Both in Greek and in Latin these general conceptions are often (though not by Lucretius) called “preconceptions,” because, once created in the mind, they remain there, and further sense impressions are referred to them for testing and identification.  However, it is important to understand that the (pre)conceptions are not innate, but derived from sensation. Indeed it is because they are derived from sensation that they are valid. Without them, memory, thought, and knowledge would be impossible, and they are the second criterion of truth.

The third criterion of truth, like the second, is bound up with sensation. This is feeling, or rather feelings—the feelings of pleasure and pain that are the supreme test in matters of conduct and morality. Pleasure and pain will be discussed shortly, and here it is necessary only to point out that Epicurus’ ethics, like his physics, is based on the validity of sensation.

We turn now to Epicurean physics, the first principles of which, established by Lucretius early in Book 1 (149–264), are that nothing can be created out of nothing, and that nothing can be reduced to nothing: compound bodies are formed and then are dissolved, but their constituent material has always existed and always will exist. The universe, which is therefore birthless and deathless, consists of just two ultimate realities—matter and void. The existence of matter is proved by sensation; and if there were no void, motion would be impossible, apparently solid objects could not be penetrated, and a ball of wool and a piece of lead of similar bulk would not have different weights, whereas sensation assures us that all these things occur (1.329–397). The extent of the universe, and that of each of its two ultimate components, is infinite, as Lucretius proves in 1.951–1051. One of his arguments (1.968–983) is justly famous. He invites us to assume that the universe is finite and to consider what would happen if someone went to the very edge of it and threw a spear. One of two things would happen: either the spear would be stopped, in which case there must be matter ahead; or the spear would fly on, in which case there must be space ahead. In neither case has the boundary of the universe been reached. Elsewhere (2.1048–1089) Lucretius argues that the number of worlds in the universe must be infinite.

In what form does uncompounded matter exist? It exists in the form of an infinite number of absolutely solid, indivisible, unmodifiable, imperishable particles or atoms (1.483–634). The Greek word atomos means “indivisible,” and so the modern atom, which has been split into subatomic particles, is really misnamed. The Epicureans argued that, unless the elements of matter were indivisible and indestructible, there could be no permanence for the universe, and indeed no existence, for everything would long ago have been reduced to nothing (1.540–550). The atoms are so small that they are individually imperceptible (1.265–328). They are uniform in substance but vary widely, though not infinitely, in shape, size, and weight, and it is these variations, as well as the variations in their movements and arrangements, that explain the diversity of things in the universe (2.333–729). Although every atom is minute, it has a certain magnitude and therefore, despite being physically indivisible, is mentally divisible into a limited number of “smallest parts,” that is to say, parts that are the minima of extension and magnitude. This interesting, but rather difficult, doctrine is expounded by Lucretius in 1.599–634, and he returns to it in 1.746–752 and 2.478–499.

All atoms, whether unattached in the void or joined in compounds, are always in motion (2.80–141). Those moving freely through the void fall downward by reason of their weight, and fall at a uniform speed despite their varying weights. The idea that they move downward is naive: there can be no “up” or “down” in infinite space. However, the idea that objects of different weights falling in a vacuum move with equal velocity—an idea that Epicurus could not prove by experiment—is correct. But his brilliant inference created a problem: the formation of compound bodies cannot take place without atoms colliding and, if all the atoms are moving in the same direction and at the same speed, how can collisions occur? The answer (2.216–293) is that at unpredictable times and places the atoms swerve very slightly from their straight course. This assumption of an atomic swerve was ridiculed for two millennia: Cicero thought it “puerile” as well as unscientific, and Lord Macaulay pronounced it to be “the most monstrous absurdity in all Epicurus’ absurd theory,” but in the modern atomic age it has been treated with more respect. An extremely important point, which emerges clearly from Lucretius’ account, is that the supposition of the swerve was made not only to explain how compound bodies can be formed, but also to account for free will, which Epicurus firmly believed in, but which the physical determinism of Democritus seemed to have excluded. More over, it would be a mistake to suppose that Epicurus argued that the irregular movement of atoms proves the existence of free will: rather, as Lucretius’ account makes clear, the argument was that the fact of free will proves the existence of the atomic swerve. Unfortunately our surviving sources do not make clear exactly how a random atomic movement makes possible actions performed by choice, but Epicurus certainly believed that by his theory he had preserved the moral independence of the individual. The very great significance that he attached to this matter can be gauged from his statement that “it would be preferable to subscribe to the legends of the gods than to be a slave to the determinism of the physicists” (Letter to Menoeceus 134). Once again we see that his moral system was of paramount importance to him.

The motion of atoms enclosed in a compound body is not linear, but vibratory, as they continually collide and rebound at intervals that vary according to the density of the substance. Why, if the component atoms of objects are continually on the move, do we not perceive their movement? The answer is simple: since the atoms themselves are imperceptible, their movements too are imperceptible (2.308–322). Every compound body, however solid it may appear to be, contains a greater or lesser amount of void. Lucretius explains that differences in the shapes of the atoms explain the differences in the density of things as well as differences in the effects that they have on our senses of taste, hearing, smell, sight, and touch (2.381–477). Hooked and branchy atoms cohere more closely together than smooth and round ones and affect our senses more harshly.

Whereas atoms are uncreated, unchangeable, and imperishable, compound bodies, no matter how solid and bulky they may be, have a beginning, undergo change, and eventually are dissolved. This is true not only of ourselves and all the things around us, but also of the totality of the world (2.1105–1174). Like every one of the infinite number of worlds in the universe, our world had a beginning and will have an end (5.91–109, 235–415). Lucretius shows that it is a natural, not a divine, creation (2.167–183; 5.156–234, 416–508); and in his brilliant account of how plants and animals originated, of how primitive human beings lived, and of how civilization developed, divine intervention is wholly excluded (5.772–1457).

The continual vibration of the component atoms of objects causes the atoms on the surface to be thrown off constantly at high speed as extraordinarily fine films shaped like the objects from which they emanate. When these filmy images (most often called eidōla in Greek and simulacra in Latin) impinge upon the eyes, they produce sight; and when they enter the mind, they cause thought, if the body is awake, or dreams, if it is asleep (4.26–521, 722–822, 877–906, 962–1036). All sensation is explained by contact. In the case of touch and taste, the contact with the object perceived is obviously direct. In the case of sight, however, the contact is, as we have seen, indirect; and the same applies to hearing and smell: these sensations too are caused by effluences entering the relevant sense organs.

The mind and spirit, the two components of the soul, are corporeal. Being parts of the body, they are born with it and die with it. Both are composed of extremely small, round, and smooth particles, which accounts for their extraordinary mobility. The spirit (anima in Latin), the seat of sensation, is distributed throughout the whole body, while the mind (animus), the seat both of thought and of emotion, is located in the breast. At death both mind and spirit are dispersed at once, and there is no more sensation or consciousness. Lucretius, who devotes the bulk of Book 3 to explanation of the nature of the mind and spirit and to proof of their mortality (3.94–829), goes on to argue that “death is nothing to us” and that fear of death is unreasonable (3.830–1094). Fear of death is, as we have seen, one of the two main obstacles to tranquillity of mind, so that it is not surprising that Lucretius devotes a whole book to his attempt to dispel it. It is to be noted that the Epicureans regarded fear of death not only as a very bad thing in itself, but also as the root cause of that feeling of insecurity that leads people to compete for wealth and power and often to commit crimes or go to war in pursuit of these objectives. Lucretius, who presents this analysis in language that strongly suggests that contemporary events such as the Catilinarian conspiracy are at the front of his mind (3.59–86), makes the paradoxical but psychologically perceptive statement that fear of death sometimes drives people to suicide (3.79–82).

The gods, fear of whom is the other main obstacle to true happiness, exist, but not as popularly conceived. They are material beings, composed of exceedingly fine atoms, but, unlike other compound bodies, they continually gain new atoms to replace those they lose, so that they enjoy immortality. Occupying “the lucid interspace of world and world,”28 they are perfectly self-sufficient, perfectly tranquil, and perfectly happy. Even if they had possessed the power to create and govern the world, to punish the wicked and reward the righteous, the whole business would have been much too troublesome for them to have undertaken it and, if they had undertaken it, the world and human beings would not have been as imperfect as they are (2.167–181; 5.156–234).  Since they have no interest in our affairs, can they be of any interest or value to us? Are they to be worshipped? One might suppose that the answer to these questions is an emphatic no, but in fact it is an emphatic yes. The gods, being perfect, do not need us, but, because they are perfect, we need them. Although they live out in space, the images that they, like all atomic compounds, discharge are able to penetrate our world. The images are so fine that they cannot be perceived by our senses, but only by our minds (5.148–149). Our visions of the gods, which we may have either when we are awake or when we are asleep, not only are proof of the existence of the gods and of their anthropomorphic character, but also convey to us something of their beauty and tranquillity (5.1169–1182). Such visions are most easily experienced by those whose minds are at peace and, although the gods cannot be influenced by prayer or sacrifice, worship of them is beneficial to the worshipper provided that the worshipper is free of popular misconceptions about them (6.68–78). Diogenes of Oinoanda, one of several writers to attest to the importance that the Epicureans attached to worship of the gods, criticizes Homer for representing them as physically or morally imperfect; and he also criticizes sculptors for portraying them as formidable and irascible: instead, he says, “We ought to make statues of the gods genial and smiling, so that we may smile back at them rather than be afraid of them” (fr. 19).29

As we have seen, Epicurus’ ethical theory, like his physical theory, is based on the validity of sensation. Since our senses inform us that pleasure is good and pain is bad, we should aim to experience as much pleasure and as little pain as possible. But by no means every pleasure is to be taken, and by no means every pain is to be avoided, because pleasure (as anyone who drinks to excess can confirm) sometimes leads to pain, and pain (as anyone who has endured the dentist’s drill knows) sometimes leads to pleasure (Letter to Menoeceus 129–130).

An important teaching is that pleasure is limited (5.1433), and that the limit of bodily pleasure is reached as soon as desire is satisfied and the pain of want is removed: after that pleasure can only be varied, not increased (Principal Doctrines 18). Important too is the distinction made between kinetic pleasure (the pleasure of movement), derived from the process of satisfying desire (for example, eating to satisfy hunger), and katastematic or static pleasure (the pleasure of equilibrium), which comes when desire is satisfied and the pain of want has been removed. In sharp contrast to the hedonistic philosophers of the Cyrenaic school, who favored the pursuit only of kinetic pleasure and did not even recognize static pleasure as a pleasure at all, Epicurus, though he did not ignore kinetic pleasure, considered static pleasure to be much more desirable, partly because it is more long lasting, partly because it is pain-free, whereas kinetic pleasure, being derived from the process of satisfying desire, is necessarily preceded by pain—the pain of unsatisfied desire.

Certainly the desires of the body, and therefore kinetic pleasure, cannot be disregarded, but most bodily pleasure is achieved not by leading a life of sensual indulgence, but by strictly limiting one’s desires and eliminating all those that are incapable of satisfaction and therefore bound to cause one pain. Desires are to be separated into three classes: natural and necessary; natural but unnecessary; neither natural nor necessary. The desires in the first class, the desires for essential food, drink, clothing, and shelter, are to be satisfied; those in the second class, including sexual desire, are to be satisfied, if they cannot be suppressed, in strict moderation and in the least disturbing way possible; and those in the third class, including the desires for wealth and status, must be eliminated because they can never be satisfied: they have no limit, so that one will always suffer the pain of want as well as anxiety that one will lose what one has acquired.

Much more important than bodily pleasure is mental pleasure. Whereas the body can feel pleasure only at the time of the pleasurable experience, the mind has the gifts of memory and anticipation: it can mitigate or eliminate present pain by the recollection of past pleasures or the expectation of pleasures to come; moreover, whereas the static pleasure of the body (freedom from pain) cannot be enjoyed all the time, because it is bound to be interrupted by the pain of physical want, it is possible, if one guides one’s life by true principles, to experience without interruption the static pleasure of the mind (freedom from disturbance). Although the mind’s ability to look back and forward is exploited by the wise to their advantage, it ruins the lives of those whose attitude to past events is bitter, and whose attitude to the future is dominated by unnecessary fears, especially of the gods and of death, and unnecessary and insatiable desires, especially for wealth and power.

The Epicureans have often been criticized for their hedonism and egoism. But their doctrine of pleasure turns out to be something much closer to asceticism than to self-indulgence. It was no advocate of la dolce vita who considered the addition of cheese to his normal bread-and-water diet a luxury (Diogenes Laertius 10.11), and who wrote to a friend concerning a young disciple, “If you wish to make Pythocles rich, do not increase his means, but diminish his desire” (Usener fr. 135). What of the charge of egoism? It is true that individuals should aim to obtain as much pleasure for themselves as possible. But, although virtue is the means to the end, which is pleasure, true pleasure is impossible without virtue and is also inseparable from friendship. The fact is that in Epicurean ethics, egoism and altruism merge.

Although Epicureanism did not offer its adherents a life after death, it did offer them a heaven on earth. “You shall live like a god among human beings,” writes Epicurus in Letter to Menoeceus (135); Lucretius states that “there is nothing to prevent us from living a life worthy of the gods” (3.322); and Diogenes of Oinoanda looks forward to the time when “truly the life of the gods will pass to human beings” (fr. 56). These statements are to be taken literally: thanks to Epicurus, it is possible to obtain on earth the perfect tranquillity of mind and happiness that the gods enjoy out in space. It is true that, whereas the gods are immortal, humans are mortal, but perfect pleasure can be achieved in a limited time, and extension of time, even to infinity, would not produce any greater pleasure (Principal Doctrines 19–20), and what Lucretius strikingly calls “deathless death” (3.869) is nothing to us—of no more concern to us than the eternity of past time was to us before we were born (3.830–842, 972–977).

4. The Structure of Lucretius’ Poem

On the Nature of Things is carefully structured.30  The six books fall naturally into three pairs. Books 1 and 2 deal with atoms and void, Book 1 establishing the basic principles of atomism and Book 2 describing the movements, properties, and combinations of the atoms. In Books 3 and 4 the focus is on psychology: in Book 3 the material and mortal nature of the mind and spirit is demonstrated, and the bulk of Book 4 is devoted to explanation of sensation and thought. Books 5 and 6 are concerned with our world and its phenomena—Book 5 with its mortality, formation, and development, Book 6 with a variety of celestial and terrestrial phenomena.

It is noticeable that in each pair it is the odd-numbered book that presents the basic doctrines, whereas the even-numbered one, though essential to Lucretius’ exposition of the Epicurean system, presents deductions from those doctrines and arguments that supplement and complement them. This pattern is certainly deliberate, and one would like to know whether it influenced the design of Virgil’s Aeneid, where dramatic books alternate with less dramatic ones, though there it is the even-numbered books that stand out in higher relief.

There is not space to mention, let alone discuss, all the structural features and patterns of Lucretius’ work, but it is important to give some attention to the opening and concluding passages of the books, not least because, as we shall see, consideration of them is relevant to the question of whether the poet is, as some think, a pessimist.

Each book has a carefully written preface. The preface to Book 1, which serves also as the preface to the whole poem, is the longest. Its sections include the opening invocation to Venus (1–43), praise of Epicurus as the moral savior of humanity (62–79), and disclosure of the philosopher-poet’s pioneering and difficult task (136–145). The opening passages of the other five books develop themes of the first preface. Proud proclamation of the writer’s mission is elaborated in the preface to Book 4.31 Praise of Epicurus’ achievement is repeated and expanded in the prefaces to Books 3, 5, and 6; and although the preface to Book 2 does not mention Epicurus, its theme is the indispensability of his philosophy. In no preface is there a trace of pessimism: in each passage Lucretius makes clear that, while those ignorant of Epicurean philosophy lead unsatisfactory and unhappy lives, those who embrace it find happiness. The message is consistently one of hope and optimism.

No book of the poem has a concluding passage, such as a modern scientific writer might provide, in which a final opinion, based on the preceding arguments, is presented. It is important to bear this point in mind, especially in connection with the concluding passage of the poem, which some have seen as evidence of Lucretius’ pessimism and final despair. I shall return to this shortly.

The concluding sections of the books, like the books to which they belong, are paired.32 Book 1 ends, if one disregards the last four lines (1114–1117), in which the poet addresses words of encouragement to Memmius, with proof of the infinity of the universe (951–1113), Book 2 with proof of the infinite number of worlds that the infinite universe contains (1023–1174). In the closing sections of Books 3 and 4 Lucretius brilliantly deploys his poetical genius, his command of rhetoric, his satirical power, and his missionary fervor to deliver with maximum effect physics-based ethical messages: the passage in Book 3 (830–1094) is concerned with an unnecessary fear—fear of death; the passage in Book 4 (1058–1287) deals predominantly with an unnecessary desire—sexual desire. In the third pair of books the relationship between the final sections is less obvious than in the other two pairs, but is very real and very important. In order to understand it properly, we must take account of what Lucretius says in the preface to Book 6, a passage that (appropriately, in view of the close links between Books 5 and 6) has many similarities to the preface of Book 5.

Book 5 ends with an account of the development of civilization (1011–1457)—an account that makes clear that, while human beings were very successful in mastering their natural environment and in making technical and cultural advances, they were not so successful in mastering themselves: whereas primitive humans usually managed to satisfy their natural and necessary desires for food, drink, and shelter, “civilized” humans are too often disturbed by unnatural and unnecessary desires as well as by unnecessary fears. In the opening passage of Book 6 (1–42), which begins with mention of Athens, the place where cultural development reached “the peak of perfection” reported in the last line of Book 5, Lucretius describes how Epicurus, a citizen of Athens, correctly diagnosed the causes of the moral sickness from which people were suffering: he saw that they had all the things apparently necessary for a good life, but that they were unhappy because they did not understand the limits of fear and desire and did not know how to cope morally with situations of adversity.

This passage, with its mention of Athens and its emphasis on moral sickness and health, not only looks back to the closing section of Book 5, but also looks forward to the closing section of Book 6 (1138–1286), an account, modeled on that of Thucydides (2.47–52), of the terrible plague of Athens in 430 b.c. Lucretius represents the plague not only as a physical calamity, but also as a moral one: the plague-stricken Athenians, living before Epicurus’ remedies were available, were philosophically, as well as medically, unequipped to deal with this situation of extreme adversity. There is the further point that the Epicureans were fond of representing the unenlightened as diseased or plague-stricken (see, for example, Cicero De Finibus 1.59; Diogenes of Oinoanda fr. 3), and there can be little doubt that the condition of the plague’s victims symbolizes for Lucretius the moral condition of those ignorant of Epicurean philosophy.33

So the account of the plague does not reflect the poet’s pessimism and despair. Rather “the prospect of salvation and of a heaven on earth which Lucretius offers . . . shines with a brighter and stronger light on account of this dark and hellish picture of what life is like without the guidance of Epicurus.”34


1. On Lucretius’ life, personality, philosophy, mission, and poetry, see also my Introduction to the Loeb edition (pp. ix-liv).

2. For Virgil’s ignorance of it, see below n. 18.

3. Nei pleniluni sereni: autobiografia immaginaria di Tito Lucrezio Caro (Longanesi: Milan, 1995). French translation by Daniel Colomar, Aux pleines lunes tranquilles: autobiographie imaginaire de Lucr`ece (Aubier: Paris, 1997).

4. Since On the Nature of Things is unfinished, it cannot have been published in the author’s lifetime.  The Cicero brothers had read Lucretius’ poetry by February 54 B.C.  So, unless he showed them his incomplete poem, the assumption that he was dead by the beginning of 54 seems certain.

5. See M. Gigante and M. Capasso, “Il ritorno di Virgilio a Ercolano,” Studi Italiani di Filogia Classica 3rd series 7 (1989) 3 - 6.

6. Amafinius’ dates are uncertain.  Modern scholars usually place him in the late second century or early first century B.C., but he may have been a contemporary of Lucretius.

7. On the structure of the poem, see section 4.

8. I do not count Memmius, who wrote some poetry that does not survive.

9. See especially E.J. Kenney, “Doctus Lucretius,” Mnemosyne 23 (1970) 366-392

10. See especially D.A. West, The Imagery and Poetry of Lucretius.

11. For detailed treatment of this feature, see M.R. Gale, Myth and Poetry in Lucretius.

12. See also 3.1042-1044, where Epicurus is described as having “outshone the human race in genius and obscured the luster of all as the rising of the ethereal sun extinguishes the stars.”

13. The idea that the unenlightened are sick, and that the Epicurean philosopher is a moral healer, is found in Lucretius (1.936-950 [repeated at 4.11-24]; 3.1070), Philodemus, Cicero, and Diogenes of Oinoanda, as well as in Epicurus himself.

14. The date usually given by modern scholars is 66, but see F. X. Ryan,  “The Tribunate of C. Memmius L. F.,” Hermes 123 (1995) 393-302.

15. On Lucretius’ debt to Empedocles, see especially D. Sedley, Lucretius and Transformation of Greek Wisdom 1-34.  The debt is a considerable one and would almost certainly be seen to be even greater if Empedocles’ On Nature survived in its entirety instead of in fragments that comprise only a fraction of the work.

16. Actually, Lucretius usually prefers to use an existing Latin word in a new sense rather than introduce a coinage.

17. Loeb edition xliv-xlv.

18. Acheron, strictly a river of the underworld, is often used by Lucretius, Virgil, and others, to mean the underworld itself. As I point out in the Loeb edition xx–xxi, it is inconceivable that Virgil could have written the lines quoted, if he had known that Lucretius had gone mad and committed suicide, for “it would have been a sarcastic and cruel comment on a man whose tragic end showed that he was anything but felix [blessed], and had anything but conquered all fears and fate and death.”

19. See, for example, the remarks of Vitruvius 9, Preface 17, written within three decades of Lucretius’ death.

20. The Stoic school, which was to be the main rival of the Epicurean school under the late Republic and early Empire, derived its name from the Painted Stoa, a colonnaded building in the Athenian Agora where Zeno taught. We do not hear of any hostility between Epicurus and Zeno, but it is difficult to imagine that they approved of one another’s views. Although Lucretius never mentions the Stoics by name, those scholars who have recently argued that he never has them in mind are almost certainly mistaken. See notes on 1.638; 4.823–857; 5.22, 110–234, 156–173, 200–203.

21. Once (we do not know when) he was shipwrecked when sailing to Lampsacus and barely escaped with his life.  See Plutarch Moralia 1090e and especially Diogenes of Oinoanda fr. 72.  The incident may partly explain his reluctance to travel.

22. Letter to Pythocles may be the compilation of a pupil, but there is no doubt about the authenticity of its content.

23. K. Kleve, “Lucretius in Herculaneum,” Cronache Ercolanesi 19 (1989) 5–27, published sixteen tiny fragments of what he believed to be a papyrus text of On the Nature of Things from the Herculaneum library. In the revised Loeb edition of 1992 (p. liv) I commented that “the fragments are so minute and bear so few certainly identifiable letters that at this stage some scepticism about their proposed authorship seems pardonable and prudent.” At the time of writing I hear that Mario Capasso claims to have proved that the fragments cannot be Lucretian, and that Kleve claims to have identified more pieces of Lucretius. At least until the relevant publications appear I shall continue to suspend judgment.

24. See D. Sedley, Lucretius and the Transformation of Greek Wisdom, especially Chapters 4-5 (pp. 94-165).

25. Possible reasons for this imbalance are considered in the Loeb edition li-lii.

26. The derivation of the word is explained in the note on 4.513.

27. See also Epicurus Letter to Herodotus 79-80, Letter to Pythocles 86-88; Philodemus De Signis; Diogenes of Oinoanda fr. 13.III.

28.  Tennyson’s description of the homes of the gods, in imitation of Lucretius 3.18-22, is quoted in full in my note on that passage.

29.  A. A. Long and D. N. Sedley, The Hellenistic Philosophers I 144–149, argue (and they are not alone in taking this line) that the gods are merely “our own instinctive thought-constructs,” being “the projections of the ethical ideal of human beings.” This theory is to be rejected: Epicurus himself calls god a “living being” and says that “the gods exist, because we have knowledge of them by clear perception” (Letter to Menoeceus 123), and, as Long and Sedley admit, Lucretius, Cicero, and Philodemus, who are the main surviving sources for Epicurean theology, agree that the gods are “a specially privileged extraterrestrial life-form.” It would be extraordinary if all three had misunderstood Epicurus’ teaching on such an important matter.

30.  The reader’s attention is drawn to the translator’s headnotes preceding the translation of each book of the poem.

31.  4.1-25.  The lines are almost identical to 1.926-950.  As well as being poetically brilliant, the passage conveys an important message – a message that Lucretius wanted to reiterate at the beginning of the second half of his poem.

32. For discussion of the finales, see R.D. Brown, Lucretius on Love and Sex 47-60.

33. See especially H. S. Commager Jr., “Lucretius’ interpretation of the Plague,” Harvard Studies in Classical Philology 62 (1957) 105-118.  See also my notes in the Loeb edition 492-493, 578-579.

34. Loeb edition 579.