46 pages • 1 hour read
LucretiusOn The Nature Of Things
Nonfiction | Essay Collection | Adult | Published in 1910A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Book IVChapter Summaries & Analyses
Book IV Summary
This book focuses on how the senses—particularly vision—receive information, and the relationship between the senses and the mind. It then segues into a discussion of vital functions, including nourishment and sexual desire.
Lucretius launches quickly into his scientific arguments, explaining that the sense of vision is made possible by images, “forms whose texture is so fine that they cannot be seen individually” (Book IV, line 89; page 102), shed by objects. These images are thin films of particles that emanate from the very surface of everything, eventually making their way to our eyes.
Images, according to Lucretius, flow from every object in a constant stream. That’s why, when you move a mirror in front of something, the mirror is immediately able to pick up its reflection. Furthermore, “...all objects must in a moment of time throw off countless images in countless ways in all directions on every side…” (Book IV, lines 164-165; page 104), which explains why you can move a mirror all the way around an object and it always reflects that side of it back. We are able to gauge distance, Lucretius tells us, because images push a current of air into our eyes, proportional to the distance they’ve traveled. It is so small and quick that we don’t consciously notice it, but that is how the eye detects distance.
Optical illusions are a fault of the mind, not the senses, which are infallible. Our senses (particularly our eyes, in this case) faithfully report precisely what they perceive, but it is up to the mind to interpret the information it has received. Things can therefore appear one way, while we consciously understand that they are in fact another way (for example, tall columns that are straight appear to be warped when we stand near them; we know, however, that they’re still straight). As Lucretius puts it, “The truth is that nothing is more difficult than to separate patent facts from the dubious opinions that our mind at once adds of its own accord” (Book IV, lines 467-468; page 112). We should therefore consider very carefully before interpreting the input from our senses.
Lucretius moves on to examine the rest of the senses, which work in essentially the same way as sight: objects shed particles that react with our sense of smell, taste, and hearing.
The evidence that sound comes from the shedding of particles is proved by the fact that talking for too long causes the body to waste away, and the voice gets scratchy from the particles it is emitting. Like images, sounds are emitted at all times and in every direction, which is why listeners can stand in different spots.
Taste operates the same way, with particles interacting with our palates in different ways to create different tastes. Lucretius explains that the “pores” (Book IV, line 651; page 118) that absorb taste particles are different in all species, which is why food that tastes good to some animals can be poison to us. Smell is similar to taste, in that different species interpret it differently according to their nature.
Lucretius reveals that “countless subtle images of things roam about in countless ways” (Book IV, line 725; page 119); these subtle images can slip past our senses and penetrate straight to our minds. This explains why people think they see ghosts or monsters, and also why we dream.
Lucretius moves on to explain how sleep works. The body and the spirit are bombarded with particles all day long, which cause the spirit to fall into disarray. It retreats deeper into the limbs, which causes fatigue. Food is similarly disruptive, since it’s introducing new particles into the system, and that is why we are sleepy after eating. We often dream about things we’ve been thinking about or working on, because our minds are particularly receptive to those sorts of images. Vivid dreams can cause physical reactions, including wet dreams.
With this, Lucretius segues into a discussion of love and sex. He advises against falling in love, as this generally causes more pain than pleasure for all parties. Casual relationships, without an investment of emotion, are fine because they fulfill the Epicurean tenet of seeking pleasure and avoiding pain. However, sex is ultimately unfulfilling, and should be avoided as much as possible.
Lucretius ends this book with a brief discussion of heredity. Both men and women have semen, he believes, and whichever partner’s seed overpowers the other’s will determine which partner their child will most resemble. Sterility is the result of overly thick or thin semen in either parent, or simple incompatibility of their seeds. “It is not the divine powers that deprive any man of procreative capacity…” (Book IV, line 1232; page 133), and so it is senseless to pray to the gods for help. Lucretius addresses which sexual positions are best for conception, and reminds the reader that wives have sex for conception, not for pleasure; prostitutes take care of the latter. Lucretius concludes with a grudging acknowledgement that sometimes force of habit can create true and lasting love: “For anything that is struck by incessant blows, no matter how lightly, in long lapse of time is overpowered and made to yield” (Book IV, lines 1286-1288; page 134).
Book IV Analysis
Lucretius opens Book IV with a reminder that he chose to present his philosophy through poetry in order to make the learning experience more pleasant. It is a fitting time for this reminder, since the majority of this book centers around science and logical argument, and he only occasionally employs poetic language in the passages regarding the senses. There is some relief when he turns his attention to love, possibly because this is a common topic in poetry, and so there are several tropes that he can employ in this discussion.
Lucretius devotes considerable attention to love, sex, and procreation. This is an opportunity to promote an Epicurean approach to love, one that embraces the pursuit of pleasure and the avoidance of pain. Passionate love, after all, causes pain; relationships are expensive, and can result in jealousy and strife: “These ills are experienced even in love that is steadfast and supremely successful; but when love is frustrated and unrequited, the miseries you can spot with your eyes shut are countless” (Book IV, lines 1141-1143; page 131). However, since sex is pleasurable, and Epicureanism encourages the pursuit of pleasure, casual relationships with no emotional attachment are acceptable. In the end, it is best to avoid even casual sexual relationships if possible, since sex does not provide lasting satisfaction: “...[lovers] seek to attain what they desire, but fail to find an effective antidote to their suffering: in such deep doubt do they pine away with an invisible wound” (Book IV, lines 1149-1121; page 130).
By equating arousal with a wound in this section, Lucretius evokes Greek erotic poetry. He argues, “The body seeks the object that has wounded the mind with love. For, as a general rule, all fall toward their wound: out gushes the blood in the direction from which the blow has been dealt…” (Book IV, lines 1048-1051; page 128). The “wound of love” is a common trope in Greek erotic poetry, with which Lucretius and his audience would certainly have been familiar. Take, for example, this excerpt from “Epigram 47” by the Greek poet Callimachus: “The Muses, O Philippus, reduce the swollen wound of love...Methinks hunger, too, hath this good and this alone in regard to evil: it drives away the disease of love. We have both remedies against thee, remorseless Love!” Such imagery, evoking the pain of unrequited or unsatisfied love, fits perfectly with the Epicurean view of the dangers of passion.
Lucretius employs another favorite trope of Greek and especially Roman love poetry, the paraclausithyron. This is a lament next to a door, expressed by a lover who is shut out of his mistress’ house. Lucretius references this device when he says, “[The mistress’] lover, so long as he is shut out, often tearfully buries her threshold under a mound of flowers and garlands...and plants lovesick kisses on the door” (Book IV, lines 1178-1180; page 132). This is a favorite trope of Lucretius’ contemporary, the Roman poet Catullus, who even addresses one entire poem (“Carmen67”) to the closed door of his lover’s house. Like the “wound of love” device above, paraclausithyron reminds the reader of Lucretius’ central argument regarding passion: that it causes more pain than pleasure.
This book suffers from a common problem that faces ancient texts: gaps in the manuscript, called lacunae. While occasional lacunae crop up elsewhere in the work, Book IV has several major gaps that seem to encompass entire arguments (especially at line 216, but see also 79, 126, 144, and 289). Before the invention of the printing press, it was difficult to mass-produce copies of any text, so many of the ancient works that have survived to this day come from only one or two manuscripts copied by hand centuries ago. We must do our best to interpret what we have, and to make educated guesses about what is missing.
