Votive relief from Eleusis, representing the goddesses Demeter and Persephone surrounding the young Triptolemus (V century B.C.), now in the National Archaeological Museum, Athens. At Eleusis was located a great temple devoted to the two goddesses. Here were celebrated rituals in their honour, which were defined as “mysteries”, because they could be attended only by the initiates (mystai). Triptolemus was the son of the king of Eleusis, Celeus, who received Demeter in his palace when she was wandering at the search of her daughter abducted by Hades, the god of the Underworld. The goddess, as a sign of gratitude, gave to the young boy a chariot driven by winged dragons and a supply of seeds, inviting him to go across the earth teaching to all mankind the arts of agriculture. Triptolemus was thus venerated as the inventor of the cultivation of cereals, and of the plough, and as the founder of civilization, which for the Greeks was based on agriculture. In this way, consolidates the opposition between the urban, “civilized” domain and the domain of the wilderness, associated with the regions more faraway from the settlements and the cultivated fields.

[Source: http://en.wikipedia.org/wiki/Demeter]