In his last of his 12 works Hercules or Heracles had to bring Cerberus the 3-headed hound of the underworld. In order to be able to do so he had himself initiated in the mysteries of Eleusis. This cult was based on the myths of the abduction of Persephone by Hades to the underworld. Hercules learned secrets so he was able to defeat the hound of hell.
