On the nature of things (books 1 - 3)   

And what the speed appointed unto them
Wherewith to travel down the vast inane:
Do thou remember to yield thee to my words.
For 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,
Unharmed, 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.
The 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.
But 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,
Or 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
These 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.
Since 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.
And all which, brought together with slight gaps,
In more condensed union bound aback,
Linked by their own all intertangled shapes,-
These form the irrefragable roots of rocks
And the brute bulks of iron, and what else
Is of their kind...
The 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-
Cast 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