On the Nature of Things

Overview

A physics textbook in hexameters, written by a Roman about whom almost nothing is known, surviving because one manuscript was found in a German monastery in 1417 by a papal secretary looking for old books. Six books, each opening with a passage of high poetry and then settling into argument, proof and worked example. The structure is deliberate: Lucretius says he is dripping honey on the rim of a cup of bitter medicine, and he means it as a description of his method.

The doctrine is not his own. It is the system of Epicurus, who died in 270 BCE and whose own writings survive mostly in fragments and three letters. Lucretius treats him as a liberator rather than a teacher, and the prefaces to Books 3 and 5 praise him in language usually reserved for gods. What Lucretius adds is the poetry, the Roman examples, and an urgency that suggests he thought his readers were in real trouble.

Expect the argument to repeat. Lucretius piles up parallel proofs, sometimes six or seven for one point, on the theory that a reader who resists one will be caught by another. Expect the similes to do real work too. Motes in a sunbeam, sheep on a distant hillside, a child spinning until the pillars seem to move: these are not decoration but evidence about scale, perception and inference.

The argument

Book 1 establishes the foundations. Nothing comes from nothing, and nothing perishes into nothing, both established by observation. Bodies exist, since the senses report them, and empty space exists, since otherwise nothing could move. All bodies are either compounds or the indivisible particles from which compounds are made. The universe is infinite in extent and in the number of its atoms, because a boundary requires something outside it to bound it. The book closes by attacking rival accounts, especially Heraclitus on fire and Anaxagoras on infinite mixture.

Book 2 sets the atoms in motion. They fall, collide, rebound and lock, and their shapes are limited in kind but unlimited in number, which explains why there are many species of things but not infinitely many. Here comes the swerve, the poem’s most contested idea: an unpredictable minimal deviation, without which the atomic rain would fall forever in parallel and nothing would exist, and which Lucretius also uses to explain why animals can initiate their own movements. The book ends by insisting there are countless other worlds, and that this one is already past its best and will come apart.

Book 3 turns to the mind. Soul and spirit are made of very fine, fast, round atoms distributed through the body, which is why they act instantly and why a body loses so little weight at death. Twenty-odd arguments follow for the soul’s mortality: it grows and ages with the body, it is disturbed by drink and disease, it can be numbed in a limb. If mind and body are born together they die together. The consequence is the poem’s central consolation. Death is not an experience that goes badly. It is the absence of any experiencer, and fearing it is a confusion, like pitying yourself for not having been alive before the Punic wars.

Book 4 explains perception by thin films of atoms that peel off surfaces and strike the eye, and uses the same machinery for dreams, mirrors, echoes and hallucination. It ends with a long, unsentimental section on sexual desire, which it treats as an appetite whose object cannot satisfy it.

Book 5 is a natural history without providence. The world assembled itself out of a chaotic mass, the earth produced living things and most early kinds failed, human beings began without language, law or fire, and civilisation arrived by degrees: shelter, then speech by convention, then metals, then kings, then property, then war, then religion.

Book 6 handles the frightening phenomena, thunder, lightning, waterspouts, earthquakes, volcanoes, magnetism and epidemic disease, on the principle that anything explained stops being an omen. The last four hundred lines describe the plague at Athens, and the poem stops there without a conclusion.

How to read it

Read the prefaces to each book first, all six of them, in one sitting. They give you the poem’s emotional shape before the physics buries it.

Then read Book 1 carefully, since every later argument depends on it, and read Book 3 twice. Book 3 is the reason most people are assigned this poem. If you are short of time, skim the optical mechanics in Book 4 and the meteorology in Book 6, but read the end of Book 5 and the plague at the end of Book 6.

Keep two questions running. First, how much of the physics is argued from observation and how much from what the system requires. Second, whether the consolation actually consoles. Lucretius offers it repeatedly and in slightly different forms, which may be a sign of thoroughness or of dissatisfaction.

Do not believe the old story that Lucretius went mad from a love potion and killed himself. It comes from a hostile note by Jerome four centuries later and there is no independent evidence for it.

Questions it raises

• Does the swerve really give us freedom, or only randomness that happens to be located inside us?
• If the gods take no interest in the world, why does the poem open by praying to Venus?
• Is death being nothing to us an argument, or a redescription that leaves the fear untouched?
• Lucretius says the senses can never be refuted. How can he then be so confident about particles no sense can detect?
• Book 5 tells a story of progress that ends in war and luxury. Is human history an improvement in this poem?
• Why would a poem written to remove fear end with four hundred lines of plague?