View of the remains of the temple of Dodona, in Epirus, where there was an oracle of Zeus, who manifested himself through the rustling of the oak leaves, the “high crested oak of the god” (Odyssey, XIV, 328). The sacredness of the site probably went back to the III millennium B.C., making it one of the most ancient cult centers of Greece. Here Zeus could have supplanted an older oracle of an earth goddess. As a matter of fact, at Dodona the god was associated not with Hera, his own wife, but with Dione, an ancient female deity whose name derives from the same root than Zeus’s own name. In the sanctuary officiated both priestesses and priests. The latter are called by Homer Selloi, of whom it is said that “slept on the ground with unwashed feet” (Iliad, XVI, 234-35), suggesting their linkage with the deity of the Earth.

[Source: http://thaumazein-albert.blogspot.it/2011/12/sanctuary-at-dodona-in-epirus.html]