Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

     Right here
I am compelled a question to expound,
Forestalling something certain folk suppose,
Lest it avail to lead thee off from truth:
Waters (they say) before the shining breed
Of the swift scaly creatures somehow give,
And straightway open sudden liquid paths,
Because the fishes leave behind them room
To which at once the yielding billows stream.
Thus things among themselves can yet be moved,
And change their place, however full the Sum-
Received opinion, wholly false forsooth.
For where can scaly creatures forward dart,
Save where the waters give them room? Again,
Where can the billows yield a way, so long
As ever the fish are powerless to go?
Thus either all bodies of motion are deprived,
Or things contain admixture of a void
Where each thing gets its start in moving on.
     Lastly, where after impact two broad bodies
Suddenly spring apart, the air must crowd
The whole new void between those bodies formed;
But air, however it stream with hastening gusts,
Can yet not fill the gap at once- for first
It makes for one place, ere diffused through all.
And then, if haply any think this comes,
When bodies spring apart, because the air
Somehow condenses, wander they from truth:
For then a void is formed, where none before;
And, too, a void is filled which was before.
Nor can air be condensed in such a wise;
Nor, granting it could, without a void, I hold,
It still could not contract upon itself
And draw its parts together into one.
Wherefore, despite demur and counter-speech,
Confess thou must there is a void in things.
     And still I might by many an argument
Here scrape together credence for my words.
But for the keen eye these mere footprints serve,
Whereby thou mayest know the rest thyself.
As dogs full oft with noses on the ground,
Find out the silent lairs, though hid in brush,
Of beasts, the mountain-rangers, when but once
They scent the certain footsteps of the way,
Thus thou thyself in themes like these alone
Can hunt from thought to thought, and keenly wind
Along even onward to the secret places
And drag out truth. But, if thou loiter loth
Or veer, however little, from the point,
This I can promise, Memmius, for a fact:
Such copious drafts my singing tongue shall pour
From the large well-springs of my plenished breast
That much I dread slow age will steal and coil
Along our members, and unloose the gates
Of life within us, ere for thee my verse
Hath put within thine ears the stores of proofs
At hand for one soever question broached.