"Go round this trench and pour offerings to all the dead"
For the ancient Greeks, part of showing proper respect to the dead involved visits to and offerings at the grave. These might consist of gifts and libations. One might also want to appease the powers of the underworld, or petition them on a deceased relative’s behalf. In The Odyssey
, Odysseus is instructed to offer the blood of a sacrificial animal to the spirits of the dead. In normal religious sacrifice, the focus lies on burning the meat so that the smoke will rise up to the gods. When honouring the spirits and gods of the Underworld, however, the offering needs to go down, to descend to Hades’ Halls below the earth. It is therefore the blood of the animal that is important. Black or barren animals were particularly appropriate for sacrifice to the chthonic deities.