The cults of Demeter were widespread in Greece, many of them being mystery cults connected with the cultivation and fertilisation of corn. The pig, originally perhaps the embodiment of Demeter or her daughter Persephone, was sacred to Demeter who was often shown carrying or accompanied by a pig. In mythology it is claimed that when Hades carried off Persephone, a swineherd called Eubouleos was with his herd on the spot where the chasm opened up and the swine, too, were engulfed when Hades vanished with Persephone. It is believed that Eubouleos became the first high priest of the Mysteries of Demeter at Eleusis.
The oldest of these Attic rites were the Thesmophoria which were celebrated in the autumn by women alone. The most important sanctuary was at Eleusis. The descent of Persephone into the lower world and, with joy, her return from the dead, was celebrated at this festival at which pigs, cakes and pine branches were thrown into a sacred cavern and their remains retrieved later to be placed on an altar; these were then distributed to the women in the belief that the fertility of the soil and of married women would be assured for the following year.
In the four-day celebrations in Athens before the pilgrimage to Eleusis the mystai-to-be had to bathe in the sea for purification and sacrifice a pig to Demeter.
Marcus Tullius Cicero (143-106 B.C.) wrote in his De Legibus of the Greek mysteries of Eleusis, "Among the many excellent and divine institutions that your Athens has developed ... there is none in my opinion, better than these mysteries, by which we have been brought forth from our rustic and savage mode of existence, cultivated and refined to a state of civilization; and as these rites are called "initiations" so, in truth, we have learned from them the first principles of life and have gained the understanding, not only to live happily, but also to die with better hope".