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 come 
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. 
And, again, 
In following wise all things seem oft to quake 
At shock of heavy thunder, and mightiest walls 
Of the wide reaches of the upper world 
There on the instant to have sprung apart, 
Riven asunder, what time a gathered blast 
Of the fierce hurricane hath all at once 
Twisted its way into a mass of clouds, 
And, there enclosed, ever more and more 
Compelleth by its spinning whirl the cloud 
To grow all hollow with a thickened crust 
Surrounding; for thereafter, when the force 
And the keen onset of the wind have weakened 
That crust, lo, then the cloud, to-split in twain, 
Gives forth a hideous crash with bang and boom. 
No marvel this; since oft a bladder small, 
Filled up with air, will, when of sudden burst, 
Give forth a like large sound. 
There's reason, too, 
Why clouds make sounds, as through them blow the winds: 
We see, borne down the sky, oft shapes of clouds 
Rough-edged or branched many forky ways; 
And 'tis the same, as when the sudden flaws 
Of northwest wind through the dense forest blow, 
Making the leaves to sough and limbs to crash. 
It happens too at times that roused force 
Of the fierce hurricane to-rends the cloud, 
Breaking right through it by a front assault; 
For what a blast of wind may do up there 
Is manifest from facts when here on earth 
A blast more gentle yet uptwists tall trees 
And sucks them madly from their deepest roots. 
Besides, among the clouds are waves, and these 
Give, as they roughly break, a rumbling roar; 
As when along deep streams or the great sea 
Breaks the loud surf. It happens, too, whenever 
Out from one cloud into another falls 
The fiery energy of thunderbolt, 
That straightaway the cloud, if full of wet, 
Extinguishes the fire with mighty noise; 
As iron, white from the hot furnaces, 
Sizzles, when speedily we've plunged its glow 
Down the cold water. Further, if a cloud 
More dry receive the fire, 'twill suddenly 
Kindle to flame and burn with monstrous sound, 
As if a flame with whirl of winds should range 
Along the laurel-tressed mountains far, 
Upburning with its vast assault those trees; 
Nor is there aught that in the crackling flame 
Consumes with sound more terrible to man 
Than Delphic laurel of Apollo lord. 
Oft, too, the multitudinous crash of ice 
And down-pour of swift hail gives forth a sound 
Among the mighty clouds on high; for when 
The wind hath packed them close, each mountain mass 
Of rain-cloud, there congealed utterly 
And mixed with hail-stones, breaks and booms... 

Likewise, it lightens, when the clouds have struck, 
By their collision, forth the seeds of fire: 
As if a stone should smite a stone or steel, 
For light then too leaps forth and fire then scatters 
The shining sparks. But with our ears we get 
The thunder after eyes behold the flash, 
Because forever things arrive the ears 
More tardily than the eyes- as thou mayst see 
From this example too: when markest thou 
Some man far yonder felling a great tree 
With double-edged ax, it comes to pass 
Thine eye beholds the swinging stroke before 
The blow gives forth a sound athrough thine ears: 
Thus also we behold the flashing ere 
We hear the thunder, w