On the nature of things (books 1 - 3)   

They yet assign them motion, and allow
Things soft and loosely textured to exist,
As air, dew, fire, earth, animals, and grains,
Without admixture of void amid their frame.
Next, because, thinking there can be no end
In cutting bodies down to less and less
Nor pause established to their breaking up,
They hold there is no minimum in things;
Albeit we see the boundary point of aught
Is that which to our senses seems its least,
Whereby thou mayst conjecture, that, because
The things thou canst not mark have boundary points,
They surely have their minimums. Then, too,
Since these philosophers ascribe to things
Soft primal germs, which we behold to be
Of birth and body mortal, thus, throughout,
The sum of things must be returned to naught,
And, born from naught, abundance thrive anew-
Thou seest how far each doctrine stands from truth.
And, next, these bodies are among themselves
In many ways poisons and foes to each,
Wherefore their congress will destroy them quite
Or drive asunder as we see in storms
Rains, winds, and lightnings all asunder fly.
Thus too, if all things are create of four,
And all again dissolved into the four,
How can the four be called the primal germs
Of things, more than all things themselves be thought,
By retroversion, primal germs of them?
For ever alternately are both begot,
With interchange of nature and aspect
From immemorial time. But if percase
Thou think'st the frame of fire and earth, the air,
The dew of water can in such wise meet
As not by mingling to resign their nature,
From them for thee no world can be create-
No thing of breath, no stock or stalk of tree:
In the wild congress of this varied heap
Each thing its proper nature will display,
And air will palpably be seen mixed up
With earth together, unquenched heat with water.
But primal germs in bringing things to birth
Must have a latent, unseen quality,
Lest some outstanding alien element
Confuse and minish in the thing create
Its proper being.
But these men begin
From heaven, and from its fires; and first they feign
That fire will turn into the winds of air,
Next, that from air the rain begotten is,
And earth created out of rain, and then
That all, reversely, are returned from earth-
The moisture first, then air thereafter heat-
And that these same ne'er cease in interchange,
To go their ways from heaven to earth, from earth
Unto the stars of the ethereal world-
Which in no wise at all the germs can do.
Since an immutable somewhat still must be,
Lest all things utterly be sped to naught;
For change in anything from out its bounds
Means instant death of that which was before.
Wherefore, since those things, mentioned heretofore,
Suffer a changed state, they must derive
From others ever unconvertible,