Hercule (Heracles) had to bring back Cerberus alive. This three-headed dog was the guardian to the Underworld: the world of the dead from which no human being could return. The hero overpowered the animal with his bare hands and brought it to Eurystheus who, terrified, ordered Hercules to take the monster back to where he found it. This labour was identified through comparison with images on sarcophagi and mosaics which illustrated this theme.