Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

     And so in first place, then,
With thunder are shaken the blue deeps of heaven,
Because the ethereal clouds, scudding aloft,
Together clash, what time 'gainst one another
The winds are battling. For never a sound there comes
From out the serene regions of the sky;
But wheresoever in a host more dense
The clouds foregather, thence more often comes
A crash with mighty rumbling. And, again,
Clouds cannot be of so condensed a frame
As stones and timbers, nor again so fine
As mists and flying smoke; for then perforce
They'd either fall, borne down by their brute weight,
Like stones, or, like the smoke, they'd powerless be
To keep their mass, or to retain within
Frore snows and storms of hail. And they give forth
O'er skiey levels of the spreading world
A sound on high, as linen-awning, stretched
O'er mighty theatres, gives forth at times
A cracking roar, when much 'tis beaten about
Betwixt the poles and cross-beams. Sometimes, too,
Asunder rent by wanton gusts, it raves
And imitates the tearing sound of sheets
Of paper- even this kind of noise thou mayst
In thunder hear- or sound as when winds whirl
With lashings and do buffet about in air
A hanging cloth and flying paper-sheets.
For sometimes, too, it chances that the clouds
Cannot together crash head-on, but rather
Move side-wise and with motions contrary
Graze each the other's body without speed,
From whence that dry sound grateth on our ears,
So long drawn-out, until the clouds have passed
From out their close positions.