King Evander explains the origins of an Italian festival

"These solemn rites,
This traditional feast, this altar sacred
To a Power divine do not come to us
From some empty superstition, ignoring
The gods of old. No, my Trojan guest,
Rescued from savage dangers, we observe
This annual rite in memory of our deliverance.
Look first at this rocky overhang,
How the huge boulders are scattered,
How the mountain stands in desolation
And the crags have crumbled in avalanche.
There was once a cave here, its depths
Never fathomed by sunlight, the lair
Of a half-human monster, an ogre named Cacus.
The ground there always smoked with fresh blood,
And nailed to the door hung human heads
Moldering in decay. The monster's father
Was Vulcan; it was his black fires Cacus belched
As he moved his hulking form. Time at last
Answered our prayers in the person
Of a god, the mightiest avenger, Hercules,
Glorying in the slaughter of Geryon
And driving that triform ghoul's huge bulls
In triumph, filling the Tiber's valley with cattle.
Cacus, whose fiendish mind could leave
No crime undared or trick untried,
Rustled four superb bulls from their corral
And as many equally outstanding heifers.
He dragged these cattle by their tails to his cave
So no one could track them back to him
Then he hid the animals in the rocky
No one searching could find any telltale marks
Leading to that cave. Amphitryon's son,
Meanwhile was moving the well-fed herds
Out of their pens rounding them up for the trail.
The cattle lowed as they headed out,
the wood and hills were filled with their bellowing
Until the echoes began to die away.
And then one heifer lowed in response
From the depths of the cave, undoing Cacus.
The wrath of Hercules flared with black bile.
He seized his weapons, his heavy, knotted club,
And ran straight up the slope like the mountain wind.
It was then we first saw Cacus afraid,
Eyes shifting with terror. He flew to his cave
Faster than the East Wind; fear lent wings to his feet.
He shut himself in and broke the chains
That held the giant rock suspended in iron
By his father's craft. The rock dropped down
Blocking the entrance, at just the moment
When Hercules arrived raging mad.
He scanned every approach looking around
And gnashing his teeth. Three times he traversed
The Aventine Mount, three times he tried
The rock-solid entrance, three times he sank down
In the valley, exhausted.
 On the cave's ridge
stood an immense dagger of flint, tall
Sheer rock, a perfect nesting place for vultures.
It leaned left with the ridge's slope toward the river.
The hero pushed from the right, shook it loose,
Wrenched it up from its roots, and abruptly
Heaved it forward. With that heave
Heaven thundered, the banks below split apart,
And the astonished river recoiled in terror.
Cacus' immense lair lay open, revealing
The shadowy depths of the cavern below:

As if Earth itself were split apart
By some unknown power, disclosing the Pit
And the moldy horror loathed by the gods.
The Abyss is laid open, and the pale ghosts
Tremble at the light streaming in from above.

Cacus was caught in the unexpected daylight.
Penned in by rock walls, he howled eerily
As Hercules rained down upon him
Everything he could throw-weapons,
Branches, colossal millstones. Cornered,
Cacus did the only thing he could, belching out
Clouds of smoke (an amazing display)
That enshrouded his subterranean home
In blinding smog shot through with dark flames.
Undeterred, Hercules hurled himself
Into the inferno where the huge cave was choked
With roiling smoke. He found Cacus there
Spewing forth his fiery vapors in vain.
Hercules gripped him in a knotted hold
And squeezed until Cacus' eyes bulged out
And his throat was drained of blood. Then,
With hardly a pause, he tore off the doors,
And the den was laid bare. The stolen oxen
(A theft Cacus had denied) were exposed
To the sky, and the gruesome carcass
Was dragged out by the feet. Men could not get enough
Of looking at those terrible eyes, that face,
The brute's bristled chest and his throat's quenched fires.
From that time on this has been a festival day
Kept by every generation, foremost by Potitius,
Who founded the rite, and the Pinarian house,
Priests of Hercules. The hero himself
Established this altar, which we will always call
Mightiest, and always mightiest shall be.
Come then, young men, wreathe your hair with leaves
In honor of these glorious deeds. Hold out your cups,
Call on the god to share our feast, and pour the wine."