On the nature of things (books 4 - 6)   

They circle their perennial courses round,
Timing their motions for increase of crops
And living creatures, or lest we should think
They roll along by any plan of gods.
For even those men who have learned full well
That godheads lead a long life free of care,
If yet meanwhile they wonder by what plan
Things can go on (and chiefly yon high things
Observed o'erhead on the ethereal coasts),
Again are hurried back unto the fears
Of old religion and adopt again
Harsh masters, deemed almighty- wretched men,
Unwitting what can be and what cannot,
And by what law to each its scope prescribed,
Its boundary stone that clings so deep in Time.

But for the rest, lest we delay thee here
Longer by empty promises- behold,
Before all else, the seas, the lands, the sky:
O Memmius, their threefold nature, lo,
Their bodies three, three aspects so unlike,
Three frames so vast, a single day shall give
Unto annihilation! Then shall crash
That massive form and fabric of the world
Sustained so many aeons! Nor do I
Fail to perceive how strange and marvellous
This fact must strike the intellect of man,-
Annihilation of the sky and earth
That is to be,- and with what toil of words
'Tis mine to prove the same; as happens oft
When once ye offer to man's listening ears
Something before unheard of, but may not
Subject it to the view of eyes for him
Nor put it into hand- the sight and touch,
Whereby the opened highways of belief
Lead most directly into human breast
And regions of intelligence. But yet
I will speak out. The fact itself, perchance,
Will force belief in these my words, and thou
Mayst see, in little time, tremendously
With risen commotions of the lands all things
Quaking to pieces- which afar from us
May she, the steersman Nature, guide: and may
Reason, O rather than the fact itself,
Persuade us that all things can be o'erthrown
And sink with awful-sounding breakage down!

But ere on this I take a step to utter
Oracles holier and soundlier based
Than ever the Pythian pronounced for men
From out the tripod and the Delphian laurel,
I will unfold for thee with learned words
Many a consolation, lest perchance,
Still bridled by religion, thou suppose
Lands, sun, and sky, sea, constellations, moon,
Must dure forever, as of frame divine-
And so conclude that it is just that those,
(After the manner of the Giants), should all
Pay the huge penalties for monstrous crime,
Who by their reasonings do overshake
The ramparts of the universe and wish
There to put out the splendid sun of heaven,
Branding with mortal talk immortal things-
Though these same things are even so far removed