Lucretius, De Rerum Natura
William Ellery Leonard, Ed.

     And when that wind
Hath splintered that cloud, then down there cleaves forthwith
Yon fiery coil of flame which still we call,
Even with our fathers' word, a thunderbolt.
The same thing haps toward every other side
Whither that force hath swept. It happens, too,
That sometimes force of wind, though hurtled forth
Without all fire, yet in its voyage through space
Igniteth, whilst it comes along, along,-
Losing some larger bodies which cannot
Pass, like the others, through the bulks of air,-
And, scraping together out of air itself
Some smaller bodies, carries them along,
And these, commingling, by their flight make fire:
Much in the manner as oft a leaden ball
Grows hot upon its aery course, the while
It loseth many bodies of stark cold
And taketh into itself along the air
New particles of fire. It happens, too,
That force of blow itself arouses fire,
When force of wind, a-cold and hurtled forth
Without all fire, hath strook somewhere amain-
No marvel, because, when with terrific stroke
'Thas smitten, the elements of fiery-stuff
Can stream together from out the very wind
And, simultaneously, from out that thing
Which then and there receives the stroke: as flies
The fire when with the steel we hack the stone;
Nor yet, because the force of steel's a-cold,
Rush the less speedily together there
Under the stroke its seeds of radiance hot.
And therefore, thuswise must an object too
Be kindled by a thunderbolt, if haply
'Thas been adapt and suited to the flames.
Yet force of wind must not be rashly deemed
As altogether and entirely cold-
That force which is discharged from on high
With such stupendous power; but if 'tis not
Upon its course already kindled with fire,
It yet arriveth warmed and mixed with heat.