On the nature of things (books 1 - 3)   

Now seeks the nature of the vast Beyond
There on the other side, that boundless sum
Which lies without the ramparts of the world,
Toward which the spirit longs to peer afar,
Toward which indeed the swift elan of thought
Flies unencumbered forth.
Firstly, we find,
Off to all regions round, on either side,
Above, beneath, throughout the universe
End is there none- as I have taught, as too
The very thing of itself declares aloud,
And as from nature of the unbottomed deep
Shines clearly forth. Nor can we once suppose
In any way 'tis likely, (seeing that space
To all sides stretches infinite and free,
And seeds, innumerable in number, in sum
Bottomless, there in many a manner fly,
Bestirred in everlasting motion there),
That only this one earth and sky of ours
Hath been create and that those bodies of stuff,
So many, perform no work outside the same;
Seeing, moreover, this world too hath been
By Nature fashioned, even as seeds of things
By innate motion chanced to clash and cling-
After they'd been in many a manner driven
Together at random, without design, in vain-
And at last those seeds together dwelt,
Which, when together of a sudden thrown,
Should alway furnish the commencements fit
Of mighty things- the earth, the sea, the sky,
And race of living creatures. Thus, I say,
Again, again, 'tmust be confessed there are
Such congregations of matter otherwhere,
Like this our world which vasty ether holds
In huge embrace.
Besides, when matter abundant
Is ready there, when space on hand, nor object
Nor any cause retards, no marvel 'tis
That things are carried on and made complete,
Perforce. And now, if store of seeds there is
So great that not whole life-times of the living
Can count the tale...
And if their force and nature abide the same,
Able to throw the seeds of things together
Into their places, even as here are thrown
The seeds together in this world of ours,
'Tmust be confessed in other realms there are
Still other worlds, still other breeds of men,
And other generations of the wild.
Hence too it happens in the sum there is
No one thing single of its kind in birth,
And single and sole in growth, but rather it is
One member of some generated race,
Among full many others of like kind.
First, cast thy mind abroad upon the living:
Thou'lt find the race of mountain-ranging wild
Even thus to be, and thus the scions of men
To be begot, and lastly the mute flocks
Of scaled fish, and winged frames of birds.
Wherefore confess we must on grounds the same
That earth, sun, moon, and ocean, and all else,
Exist not sole and single- rather in number
Exceeding number. Since that deeply set
Old boundary stone of life remains for them