Editor’s note: This is the eighth in a series of essays on Lucretius, an early philosopher who provides a link to “lost classics” through his epic poem “On the Nature of Things.”
Some recent interpreters of Lucretius have made much of what they perceive to be a paradox in his poem. They believe that it undermines his theory and makes it, if not untrue, at least doubtful, for a paradox is a seeming contradiction. They note that Lucretius claims that all our knowledge depends upon sensory experience, yet the things he takes to be ultimately real, atoms and infinite space, are, they suppose, notoriously unseen.
This is the paradox: experience grounding its theories upon the supposed reality of things that one can never hope to experience, or to experience directly. The ultimate things of his theory of nature are products of hypothesis and inference, and they could never have been more to him than mere ideas, not the robust ideas of Plato, but transient things occupying episodes of thought, which are themselves transient.
Besides, although only a fool or a philosopher, or a foolish philosopher, would deny the existence of bodies, because we are every waking moment of every day in touch with them, most immediately our own, as well as the floor or the earth beneath, or table supporting our elbow, this imposing presence can be misleading and cause us to draw false conclusions about the nature of things.
The English philosopher John Locke, celebrated as the founder of modern empiricism, believed that all the content of thinking, and therefore of knowing, derives from experience; our ideas of physical things, from sensory experience. Prominent among these was idea of solidity, which he believed was an essential property of all bodies. He claimed that our idea of solidity was too simple, too fundamental to be defined verbally. It had to be experienced in a way such as this: Take an object, hard or soft, a stone or a sponge or anything near at hand, and place it between your hands and squeeze. No matter how hard you press, your hands will never meet, unless the object be squeezed out. That feeling, of an unconquerable resistance, is what the word “solidity” means.
He regarded this phenomenon as constant proof that all natural things are corpuscular, that nature consists of solid bodies all the way down to the ground of being, to atoms, which, following Lucretius, he supposed existed in a state of solid singleness, eternally indivisible. From this evidence, he inferred some primary physical axioms, that no two bodies could occupy the same place at the same time, and no two bodies could have the same beginning, for to have the same beginning would mean to be in exactly the same place.
Yet we have since learned, by means not available to either Lucretius or Locke, that atoms are divisible, not solid, and some subatomic particles, namely bosons, can be in the same place at the same time and that they pass through one another with ease.
Nonetheless, visible solid bodies are still solid to the touch, and they can’t be in the same place at the same time. What is needed is to find one’s way from what the senses observe to the unseen processes that explain them. It becomes necessary, if our knowledge of the nature of things is to enlarge, to comprehend the forces and the operations of things at levels of reality not immediately imperceptible to us.
And Lucretius’ poem offers clues about how to do this. In the fourth book, he makes us aware the world is not a statuary of gross unmoving bodies, but a dynamic collection of things in constant motion, not self-contained but sending out or casting off their substance. He observes that reality consists of bodies that are constantly, sometimes imperceptibly, throwing off bodies, “wood throws off smoke, and fire heat,” cicadas and snakes shed their outer skin, and calves their caul. And most physical things are constantly giving off films, sweet fragrances or vile odors, effluvia that strike the several senses in various ways.
Lucretius was especially fascinated with visual images. If we sit in a large theater under a loose, richly colored canvas awning, the things beneath them are bathed and dyed in rich fluttering hues, yellow, red or purple, depending on the color of the awning, which is infused with light, translucent.
Then there are the images of things seen in mirrors, or in water. He asked how it is that we can see an object reflected in a mirror in perfect detail, although reversed, and in the flat surface of a mirror we see not only the face of an object, and perspective? He marvels that “a puddle of water, no more than one finger deep, lying between the stones upon a paved street” can mirror the heavens, “so that you seem to look down upon the clouds of heaven as though it were buried deep within the earth.” And more, how is it that things reverse themselves in mirrors, and other curious effects follow, when a mirror is convex or concave?
We cannot deny that we see these strange things, or that we really smell, taste and sometimes touch the dynamic flow of things or currents of energy running through the body. All sense perceptions are true, for they cannot be altered at will or refuted by argument.
Take, for example, a common mirage. Almost everyone reading these lines will have experienced driving down a highway on a hot dry summer day, seeing what appears to be water on the road ahead. Or parallel lines of columns that seem to meet in the distance, or the sun rising out of the sea, or setting just behind a nearby mountain, or, as we approach a city from a distance, its square towers seem round, as though their sharp corners were smoothed out on a lathe.
We go astray by rushing to the conclusion that the senses deceive us, and that, therefore, they are unreliable, that we must fly to some other source and standard of reality and truth, or take refuge in Platonism. Democritus is quoted as having said, “In reality, we know nothing, for truth is in the depths.” What he meant was that the paradoxes of everyday perception: Square towers appearing round, a shallow puddle revealing the vast expanse of the heavens as though it were in the earth’s deep, and suchlike, are evidences or signs of the operations of nature, which are not immediately evident to the senses, but, to the properly curious, they can be searched out, and by analogy, hypothesis, and experiment made known.
For this, he has been hailed as the founder of natural philosophy, of the empirical search for explanations, which is also a search for reality, which holds the deepest truth of all.