In the Celtic calendar, Lammas (or Lughnasadh) represents the first of three harvest festivals, the time when the mythological grain God is sacrificed. The grinding of the grain represents his death, baking it into bread represents rebirth in the womb of the Goddess, and eating the bread brings new life.
The Serpent Goddess is invoked at Lammas because of her role in rebirth and in protection of grain. Serpents used to be kept in households to safeguard the domestic food supply from rodents. Even today, serpents protect grain crops. Snake meat became so popular in restaurants in China at the start of the Year of the Snake in 2001 that the crops were threatened due to the uncontrolled population explosion of mice.
The Greek Goddess of grain, Demeter, was often depicted with her sacred serpent, as in a terra-cotta relief from the 5th century BCE showing Demeter holding wheat and poppy pods, with snakes facing her.
Demeter is best known as the Goddess who brings winter to the Earth when her beloved daughter, Persephone, is in the Underworld with her consort, Hades. The myth of Demeter's search for her kidnapped daughter was reenacted in ritual in the Greek mystery festival known as the Thesmophoria, which was exclusively for women. The actual rites were practiced in great secrecy, but we have a general idea of what may have taken place during the Thesmophoria.
Ritual objects, believed to be a sacrificed piglet and replicas of serpents and phalluses made of flour, were thrown into snake-filled chambers. Poet Robert Graves believed that originally the ritual objects included the severed genitals of the sacrificed king, or of his surrogate. The presence of serpents in the chamber, and the serpent loaves, suggests the theme of renewal during this festival. On the final day of the three-day festival, the women would descend into the chamber and retrieve the ritual objects, clapping to frighten away the snakes. They mixed the rotted sacrifices with grain, and put the mixture on the fields to ensure the fertility of the crops. In ancient Greece, the Thesmophoria was celebrated in the fall. It is appropriate, however, to invoke Demeter as the Goddess of grain at Lammas, the earliest harvest festival.