On the nature of things (books 1 - 3)   

And travail and perish equally with those,
And no rein curbs therm from annihilation.
For which will last against the grip and crush
Under the teeth of death? the fire? the moist?
Or else the air? which then? the blood? the bones?
No one, methinks, when every thing will be
At bottom as mortal as whate'er we mark
To perish by force before our gazing eyes.
But my appeal is to the proofs above
That things cannot fall back to naught, nor yet
From naught increase. And now again, since food
Augments and nourishes the human frame,
'Tis thine to know our veins and blood and bones
And thews are formed of particles unlike
To them in kind; or if they say all foods
Are of mixed substance having in themselves
Small bodies of thews, and bones, and also veins
And particles of blood, then every food,
Solid or liquid, must itself be thought
As made and mixed of things unlike in kind-
Of bones, of thews, of ichor and of blood.
Again, if all the bodies which upgrow
From earth, are first within the earth, then earth
Must be compound of alien substances earth.
Which spring and bloom abroad from out the earth.
Transfer the argument, and thou may'st use
The selfsame words: if flame and smoke and ash
Still lurk unseen within the wood, the wood
Must be compound of alien substances
Which spring from out the wood.
Right here remains
A certain slender means to skulk from truth,
Which Anaxagoras takes unto himself,
Who holds that all things lurk commixed with all
While that one only comes to view, of which
The bodies exceed in number all the rest,
And lie more close to hand and at the fore-
A notion banished from true reason far.
For then 'twere meet that kernels of the grains
Should oft, when crunched between the might of stones,
Give forth a sign of blood, or of aught else
Which in our human frame is fed; and that
Rock rubbed on rock should yield a gory ooze.
Likewise the herbs ought oft to give forth drops
Of sweet milk, flavoured like the uddered sheep's;
Indeed we ought to find, when crumbling up
The earthy clods, there herbs, and grains, and leaves,
All sorts dispersed minutely in the soil;
Lastly we ought to find in cloven wood
Ashes and smoke and bits of fire there hid.
But since fact teaches this is not the case,
'Tis thine to know things are not mixed with things
Thuswise; but seeds, common to many things,
Commixed in many ways, must lurk in things.
"But often it happens on skiey hills" thou sayest,
"That neighbouring tops of lofty trees are rubbed
One against other, smote by the blustering south,
Till all ablaze with bursting flower of flame."
Good sooth- yet fire is not ingraft in wood,
But many are the seeds of heat, and when
Rubbing together they together flow,
They start the conflagrations in the forests.
Whereas if flame, already fashioned, lay
Stored up within the forests, then the fires