Hercules and Cacus
At a Glance
- Central figures: Hercules, the son of Jupiter, returning from Iberia with the cattle of Geryon; and Cacus, a fire-breathing giant and son of Vulcan, who haunted a cave on the Aventine Hill.
- Setting: The site of future Rome - the Aventine Hill, the Tiber’s bank, and the cattle pasture near the Palatine - in the age before Romulus, during the reign of the Arcadian exile Evander.
- The turn: Cacus stole part of Hercules’ herd by dragging the cattle backward into his cave so their hoofprints pointed outward, away from his lair.
- The outcome: Hercules discovered the theft, tore open Cacus’s cave, and strangled the monster in its own smoke and darkness, recovering the stolen cattle.
- The legacy: The Ara Maxima - the Great Altar of Hercules in the Forum Boarium - was established at the site by Evander and maintained for centuries as Rome’s oldest cult, where oaths were sworn and tithes offered, and where no dogs were permitted within the sacred precinct.
The cattle were still lowing when Hercules brought them down along the Tiber. He had driven them from Iberia - Geryon’s herd, red-coated and heavy, taken as one of the labors imposed by the king of Tiryns. The route home wound along the western coast of Italy, and when Hercules reached the river crossing near the Palatine, the grass was good and the water clean. He let the herd graze. He slept.
He should not have slept there. Something lived in the Aventine.
The Cave on the Aventine
Cacus, son of Vulcan, had made his home in a cave on the western slope of the Aventine Hill. The cave went deep. The entrance was littered with bones - human bones, animal bones, the skulls of travelers who had stopped at the river and never continued. Cacus was enormous, half-formed, more beast than man, and from his throat he could vomit fire and black smoke that filled his cave like a furnace. The locals - Evander’s Arcadian settlers, the scattered Latin herdsmen - gave the hill a wide margin. No one entered the cave. No one challenged Cacus. They left offerings at the edge of his territory and hoped he would eat their goats instead of their children.
Virgil, in the eighth book of the Aeneid, has Evander describe the scene to Aeneas centuries later: the doors of the cave nailed with rotting heads, the ground dark with gore. Evander had prayed, he said. Everyone had prayed. The gods had not answered - not until Hercules arrived with someone else’s cattle and an appetite for killing monsters.
The Theft
Cacus watched the herd from above. He counted them. He waited until Hercules was deep in sleep, then crept down in the dark and selected the finest animals - four bulls and four heifers, according to Livy. But Cacus was cunning in the way that scavengers are cunning. He did not drive the cattle forward into his cave. He seized them by their tails and dragged them backward, so that their hoofprints in the soft ground along the river pointed away from the Aventine rather than toward it. Anyone tracking the herd would follow the prints in the wrong direction.
He hauled the animals up the slope and into the cave. He rolled a boulder across the entrance - a rock so massive that, Virgil says, ten yoked oxen could not have shifted it. Then Cacus sat in the dark with his stolen cattle and his fire, and waited for Hercules to leave.
The Bellowing
At dawn Hercules woke and counted the herd. Eight animals short. He walked the perimeter. He found tracks leading away from the river, downstream, in the wrong direction. He followed them for a while, found nothing, doubled back. The remaining cattle were restless, calling out, and from somewhere inside the Aventine a sound answered - muffled, subterranean, but unmistakable. One of the stolen cows was bellowing back.
Hercules stopped. He looked at the hill. The sound came again, faint and hollow, from behind stone.
He did not need to read the tracks anymore.
The Stone Torn Open
Hercules climbed the Aventine. He found the boulder. He set his hands against it and pushed, but Cacus had wedged it from within, and the stone held. So Hercules went higher. He found the place where the cave’s roof came closest to the surface - a shelf of rock above the cavern - and he began to tear it apart. He ripped the capstone from the hill. Virgil’s description is precise: the whole ridge shuddered, the riverbanks recoiled, and suddenly the cave lay open to the sky like a crack in the earth.
Cacus was exposed below, blinking in the sudden light, the stolen cattle behind him. He did what he could. He vomited fire and smoke upward into the opening, filling the shaft with black fumes so thick that Hercules could not see his own hands. The cave became a furnace with the lid torn off.
Hercules jumped in anyway.
He landed in the smoke. Cacus hurled fire at him. Hercules seized the giant - Livy says by the throat, Virgil says in a wrestler’s hold, wrapping his arms around the massive torso. Cacus could not breathe his flames with his windpipe crushed. His eyes burst from the pressure. Hercules squeezed until the fire went out and the body went slack, then dropped the corpse on the floor of the ruined cave.
When the smoke cleared, the stolen cattle walked out into the morning over Cacus’s body.
Evander and the Altar
Evander, the Arcadian king who had settled his people on the Palatine, came down to the river to see what had shaken his hill. He found Hercules standing among the recovered herd with soot on his skin and Cacus dead in the open cave above. Evander recognized what he was looking at. He had heard the prophecy from his mother, the seer Carmenta: that a son of Jupiter would come to this place and kill the thing on the Aventine.
Evander built an altar on the spot - the Ara Maxima, the Great Altar, in what would later become the Forum Boarium, Rome’s cattle market. He established rites. He appointed the Potitii and Pinarii, two local families, as hereditary priests of the cult. Hercules himself, according to the tradition, instructed them in the proper forms of sacrifice. The Potitii arrived on time and received the meat and entrails; the Pinarii arrived late and were excluded from the inner portions forever after.
The Ara Maxima stood for centuries. Roman generals tithed a tenth of their spoils there before triumphs. Merchants swore oaths at the altar with their heads uncovered - a Greek custom preserved in this one Roman rite, because Hercules was Greek and the cult remembered it. No women were permitted at the sacrifice. No dogs were allowed within the precinct. The reasons were old enough that even the antiquarians disagreed about them.
The cave on the Aventine eventually collapsed or was built over. The cattle market remained. The altar remained. And when Aeneas arrived at the same riverbank, generations later, Evander told him the whole story - the bones at the cave mouth, the backward hoofprints, the stone torn open - while the smoke of a fresh offering to Hercules rose from the Ara Maxima behind them.