Lucretius's Of the Nature of Things: Atoms and the Void

This post is an introduction to the Roman poet Lucretius’s De rerum natura, which I feel will help prepare the discussion in my next post, which will present the atomism in Galileo’s Two New Sciences.

If we look for the earliest writings on atomism in ancient Greece, we will not find them. Of the writings of Leucippus (480–420 BCE?) and Democritus (460–370 BCE?), only fragments remain, typically quotes recorded in the writings of other authors, such as Aristotle (384-322 BCE). And the writings of Epicurus (341–270 BCE) are mostly lost as well. So the first complete text from the ancient world vaunting atomism is the De rerum natura (Of the Nature of Things¹), a long poem by the Roman Titus Lucretius Carus (99-55 BCE?), which has been translated into English numerous times. I will be quoting below from William Ellery Leonard’s version, first published in 1912.

The poetic approach to the presentation does take some getting used to. In some cases, the flowery language does not help with comprehension. On the other hand, poetry better supports redundancy, and it is possible for Lucretius to repeat the same thing several times, which ultimately helps with the message.

Of course, different translations will give very different impressions. For example, I picked up in the streets of Bogotá a recent Spanish-language translation² of De rerum natura, and I find the language to be much more direct than in Leonard’s English-language translation. At times I have read these two versions simultaneously.

The De rerum natura is composed of six books. In this post, I will focus on the first book, in which he puts forward his understanding of the composition of the Universe. In each quoted passage below, I have highlighted some lines that I consider to be key.

The first book begins with a proem [preface], in which Lucretius states that all of Nature is ultimately made up of atoms, also called primal bodies or primordial germs:

And for the rest, summon to judgments true,
Unbusied ears and singleness of mind
Withdrawn from cares; lest these my gifts, arranged
For thee with eager service, thou disdain
Before thou comprehendest: since for thee
I prove the súpreme law of Gods and sky,
And the primordial germs of things unfold,
Whence Nature all creates, and multiplies
And fosters all, and whither she resolves
Each in the end when each is overthrown.
This ultimate stock we have devised to name
Procreant atoms, matter, seeds of things,
Or primal bodies, as primal to the world. [pp.5-6, my emphasis]

In the next section, entitled “Substance is Eternal”, he insists that no thing, in its creation, ever arises from nothing. We can consider this statement to be a precursor of the law of conservation of mass.

Nothing from nothing ever yet was born. [p.8, my emphasis]

Else would ye mark, without all toil of ours,
Spontaneous generations, fairer forms.
Confess then, naught from nothing can become,
Since all must have their seeds, wherefrom to grow,
Wherefrom to reach the gentle fields of air. [p.10, my emphasis]

In turn, upon its destruction, no thing returns to nothing:

Nothing returns to naught; but all return
At their collapse to primal forms of stuff. [p.11, my emphasis]

It follows that the atoms must be invisible to our eyes:

And now, since I have taught that things cannot
Be born from nothing, nor the same, when born,
To nothing be recalled, doubt not my words,
Because our eyes no primal germs perceive;
For mark those bodies which, though known to be
In this our world, are yet invisible [p.12, my emphasis]

Thus nature ever by unseen bodies works. [p.14, my emphasis]

In the next section, entitled “The Void”, Lucretius insists that the void [vacuum] exists, and that without this void, motion would not be possible. This is a direct rebuttal to Aristotle, who claimed that the void could not exist, as motion therein would be infinitely fast.

But yet creation’s neither crammed nor blocked
About by body: there’s in things a void—
Which to have known will serve thee many a turn,
Nor will not leave thee wandering in doubt,
Forever searching in the sum of all,
And losing faith in these pronouncements mine.
There’s place intangible, a void and room.
For were it not, things could in nowise move;
Since body’s property to block and check
Would work on all and at all times the same.
Thus naught could evermore push forth and go,
Since naught elsewhere would yield a starting place.
But now through oceans, lands, and heights of heaven,
By divers causes and in divers modes,
Before our eyes we mark how much may move,
Which, finding not a void, would fail deprived
Of stir and motion; nay, would then have been
Nowise begot at all, since matter, then,
Had staid at rest, its parts together crammed.
Then too, however solid objects seem,
They yet are formed of matter mixed with void [p.14, my emphasis]

Which but for voids for bodies to go through
'Tis clear could happen in nowise at all. [p.15, my emphasis]

The void is also necessary to provide space for bodies to come apart and for new bodies to come together. Furthermore, when two bodies are separated, first the void is created, then the air rushes in to fill the void.

Lastly, where after impact two broad bodies
Suddenly spring apart, the air must crowd
The whole new void between those bodies formed;
But air, however it stream with hastening gusts,
Can yet not fill the gap at once—for first
It makes for one place, ere diffused through ail.
And then, if haply any think this comes,
When bodies spring apart, because the air
Somehow condenses, wander they from truth:
For then a void is formed, where none before;
And, too, a void is filled which was before.
Nor can air be condensed in such a wise;
Nor, granting it could, without a void, I hold,
It still could not contract upon itself
And draw its parts together into one.
Wherefore, despite demur and counter-speech,
Confess thou must there is a void in things. [p.16, my emphasis]

The title of the next section is self-explanatory: “Nothing exists per se except Atoms and the Void”:

But, now again to weave the tale begun,
All nature, then, as self-sustained, consists
Of twain of things: of bodies and of void
In which they’re set, and where they’re moved around.
For common instinct of our race declares
That body of itself exists: unless
This primal faith, deep-founded, fail us not,
Naught will there be whereunto to appeal
On things occult when seeking aught to prove
By reasonings of mind.  Again, without
That place and room, which we do call the inane,
Nowhere could bodies then be set, nor go
Hither or thither at all—as shown before.
Besides, there’s naught of which thou canst declare
It lives disjoined from body, shut from void—
A kind of third in nature. [p.17, my emphasis]

Again, whate’er exists, as of itself,
Must either act or suffer action on it,
Or else be that wherein things move and be
Naught, saving body, acts, is acted on;
Naught but the inane can furnish room.  And thus,
Beside the inane and bodies, is no third
Nature amid the number of all things—
Remainder none to fall at any time
Under our senses, nor be seized and seen
By any man through reasonings of mind. [pp.17-18, my emphasis]

The last section of our concern, entitled “Character of the Atoms”, explains that there is void between the atoms of complex bodies:

First since we know a twofold nature exists,
Of things, both twain and utterly unlike—
Body, and place in which all things go on—
Then each must be both for and through itself,
And all unmixed: where’er be empty space,
There body’s not; and so where body bides,
There not at all exists the void inane.
Thus primal bodies are solid, without a void.
But since there’s void in all begotten things,
All solid matter must be round the same;
Nor, by true reason canst thou prove aught hides
And holds a void within its body, unless
Thou grant what holds it be a solid. Know,
That which can hold a void of things within
Can be naught else than matter in union knit. [p.20, my emphasis]

In conclusion, Lucretius views that Nature is the interplay of body and void.

Again, were naught of empty and inane,
The world were then a solid; as, without
Some certain bodies to fill the places held,
The world that is were but a vacant void.
And so, infallibly, alternate-wise
Body and void are still distinguishèd,
Since nature knows no wholly full nor void. [pp.20-21, my emphasis]

In the next post, I will endeavor to show that some passages of Galileo’s Two New Sciences recall Lucretius’s De rerum natura.

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1. T. Lucretius Carus. Of the Nature of Things. A Metrical Translation by William Ellery Leonard. Everyman’s Library. London: J. M. Dent & Sons, New York: E. P. Dutton & Co., 1921.

2. Lucrecio. De la naturaleza de las cosas. Translated by Abate Marchena. Ediciones Altaya, 1995. First published by Ediciones Cátedra, 1990.