On the Nature of Things by Lucretius — Book II, The motion of the atoms

Now come: I will untangle for thy steps
Now by what motions the begetting bodies
Of the world-stuff beget the varied world,
And then forever resolve it when begot,
And by what force they are constrained to this,
And what the speed appointed unto them
Wherewith to travel down the vast inane:
Do thou remember to yield thee to my words.
⁶⁷For truly matter coheres not, crowds not tight,
Since we behold each thing to wane away,
And we observe how all flows on and off,
As 'twere, with age-old time, and from our eyes
How eld withdraws each object at the end,
Albeit the sum is seen to bide the same,
⁷²Unharmed, because these motes that leave each thing
Diminish what they part from, but endow
With increase those to which in turn they come,
Constraining these to wither in old age,
And those to flower at the prime (and yet
Biding not long among them). Thus the sum
Forever is replenished, and we live
As mortals by eternal give and take.
⁷⁷The nations wax, the nations wane away;
In a brief space the generations pass,
And like to runners hand the lamp of life
One unto other.

⁸⁰But if thou believe
That the primordial germs of things can stop,
And in their stopping give new motions birth,
Afar thou wanderest from the road of truth.
For since they wander through the void inane,
All the primordial germs of things must needs
Be borne along, either by weight their own,
⁸⁵Or haply by another's blow without.
For, when, in their incessancy so oft
They meet and clash, it comes to pass amain
They leap asunder, face to face: not strange-
Being most hard, and solid in their weights,
And naught opposing motion, from behind.
And that more clearly thou perceive how all
⁹⁰These mites of matter are darted round about,
Recall to mind how nowhere in the sum
Of All exists a bottom,- nowhere is
A realm of rest for primal bodies; since
(As amply shown and proved by reason sure)
Space has no bound nor measure, and extends
Unmetered forth in all directions round.
⁹⁵Since this stands certain, thus 'tis out of doubt
No rest is rendered to the primal bodies
Along the unfathomable inane; but rather,
Inveterately plied by motions mixed,
Some, at their jamming, bound aback and leave
Huge gaps between, and some from off the blow
Are hurried about with spaces small between.
¹⁰⁰And all which, brought together with slight gaps,
In more condensed union bound aback,
Linked by their own all inter-tangled shapes,-
These form the irrefragable roots of rocks
And the brute bulks of iron, and what else
Is of their kind...
¹⁰⁵The rest leap far asunder, far recoil,
Leaving huge gaps between: and these supply
For us thin air and splendour-lights of the sun.
And many besides wander the mighty void-
¹¹⁰Cast back from unions of existing things,
Nowhere accepted in the universe,
And nowise linked in motions to the rest.
And of this fact (as I record it here)
An image, a type goes on before our eyes
Present each moment; for behold whenever
The sun's light and the rays, let in, pour down
¹¹⁵Across dark halls of houses: thou wilt see
The many mites in many a manner mixed
Amid a void in the very light of the rays,
And battling on, as in eternal strife,
And in battalions contending without halt,
¹²⁰In meetings, partings, harried up and down.
From this thou mayest conjecture of what sort
The ceaseless tossing of primordial seeds
Amid the mightier void- at least so far
As small affair can for a vaster serve,
And by example put thee on the spoor
Of knowledge. For this reason too 'tis fit
¹²⁵Thou turn thy mind the more unto these bodies
Which here are witnessed tumbling in the light:
Namely, because such tumblings are a sign
That motions also of the primal stuff
Secret and viewless lurk beneath, behind.
For thou wilt mark here many a speck, impelled
By viewless blows, to change its little course,
¹³⁰And beaten backwards to return again,
Hither and thither in all directions round.
Lo, all their shifting movement is of old,
From the primeval atoms; for the same
Primordial seeds of things first move of self,
And then those bodies built of unions small
¹³⁵And nearest, as it were, unto the powers
Of the primeval atoms, are stirred up
By impulse of those atoms' unseen blows,
And these thereafter goad the next in size:
Thus motion ascends from the primevals on,
And stage by stage emerges to our sense,
Until those objects also move which we
¹⁴⁰Can mark in sunbeams, though it not appears
What blows do urge them.

¹⁴²Now what the speed to matter's atoms given
Thou mayest in few, my Memmius, learn from this:
When first the dawn is sprinkling with new light
The lands, and all the breed of birds abroad
Flit round the trackless forests, with liquid notes
Filling the regions along the mellow air,
We see 'tis forthwith manifest to man
¹⁴⁷How suddenly the risen sun is wont
At such an hour to overspread and clothe
The whole with its own splendour; but the sun's
Warm exhalations and this serene light
Travel not down an empty void; and thus
They are compelled more slowly to advance,
¹⁵²Whilst, as it were, they cleave the waves of air;
Nor one by one travel these particles
Of the warm exhalations, but are all
Entangled and enmassed, whereby at once
Each is restrained by each, and from without
Checked, till compelled more slowly to advance.
¹⁵⁷But the primordial atoms with their old
Simple solidity, when forth they travel
Along the empty void, all undelayed
By aught outside them there, and they, each one
Being one unit from nature of its parts,
Are borne to that one place on which they strive
Still to lay hold, must then, beyond a doubt,
¹⁶²Outstrip in speed, and be more swiftly borne
Than light of sun, and over regions rush,
Of space much vaster, in the self-same time
The sun's effulgence widens round the sky.
. . . . . .
Nor to pursue the atoms one by one,
To see the law whereby each thing goes on.
¹⁶⁷But some men, ignorant of matter, think,
Opposing this, that not without the gods,
In such adjustment to our human ways,
Can nature change the seasons of the years,
And bring to birth the grains and all of else
¹⁷²To which divine Delight, the guide of life,
Persuades mortality and leads it on,
That, through her artful blandishments of love,
It propagate the generations still,
Lest humankind should perish. When they feign
That gods have stablished all things but for man,
They seem in all ways mightily to lapse
From reason's truth: for ev'n if ne'er I knew
¹⁷⁷What seeds primordial are, yet would I dare
This to affirm, ev'n from deep judgment based
Upon the ways and conduct of the skies-
This to maintain by many a fact besides-
That in no wise the nature of the world
For us was builded by a power divine-
So great the faults it stands encumbered with:
¹⁸²The which, my Memmius, later on, for thee
We will clear up. Now as to what remains
Concerning motions we'll unfold our thought.

¹⁸⁴Now is the place, meseems, in these affairs
To prove for thee this too: nothing corporeal
Of its own force can e'er be upward borne,
Or upward go- nor let the bodies of flames
Deceive thee here: for they engendered are
With urge to upwards, taking thus increase,
¹⁸⁹Whereby grow upwards shining grains and trees,
Though all the weight within them downward bears.
Nor, when the fires will leap from under round
The roofs of houses, and swift flame laps up
Timber and beam, 'tis then to be supposed
They act of own accord, no force beneath
¹⁹⁴To urge them up. 'Tis thus that blood, discharged
From out our bodies, spurts its jets aloft
And spatters gore. And hast thou never marked
With what a force the water will disgorge
Timber and beam? The deeper, straight and down,
We push them in, and, many though we be,
The more we press with main and toil, the more
¹⁹⁹The water vomits up and flings them back,
That, more than half their length, they there emerge,
Rebounding. Yet we never doubt, meseems,
That all the weight within them downward bears
Through empty void. Well, in like manner, flames
Ought also to be able, when pressed out,
²⁰⁴Through winds of air to rise aloft, even though
The weight within them strive to draw them down.
Hast thou not seen, sweeping so far and high,
The meteors, midnight flambeaus of the sky,
How after them they draw long trails of flame
Wherever Nature gives a thoroughfare?
²⁰⁹How stars and constellations drop to earth,
Seest not? Nay, too, the sun from peak of heaven
Sheds round to every quarter its large heat,
And sows the new-ploughed intervales with light:
Thus also sun's heat downward tends to earth.
Athwart the rain thou seest the lightning fly;
²¹⁴Now here, now there, bursting from out the clouds,
The fires dash zig-zag- and that flaming power
Falls likewise down to earth.