It would be easy to simplify Demeter's function to goddess of the grain and harvest. But in reality, Demeter's function to the ancient Greek was way beyond that.
In Dorian or Aeolic dialects, her name was Damater, and she is probably of Asian origin, but that is speculation. Her role as a mother has been well noted, but it is unclear exactly what type of mother she really was. Gaea plays the role of the Earth Mother in the Greek religion, so Demeter wouldn't possibly fill that role, and through time, she has been categorized simply as the grain mother. Of course, grain and corn play large parts in her mysteries, but only symbolically. It is possible that the grain or corn was used as an example of the mystery of death and rebirth. This is also played out in the well-known myth of the rape of her daughter, Persephone.
It is known that Demeter was one of the children of Kronos. And by her brother Zeus, bore Persephone, her daughter. She also had a son, Plutos, who was conceived in a field plowed three times by a father who has been much disputed., although there are tales of her union with Posideon, god of the sea. Plutos represents the wealth of the harvest, or the reward of the harvest.
Persephone, or Kore, has played a central role in the mythos of Demeter. Whether or not Kore/Persephone was raped or taken willingly has been debated over and over again, and we will not go into it here. However, she was taken from a field where she was picking flowers by Hades-Aidoneus, the personification of the Underworld. Demeter flew into a rage and searched the world for her daughter, finally refusing to let the harvest plants grow until Kore/Persephone was returned to her. During her wandering and mourning, she visited Eleusis where her mysteries were founded at her insistance. Her travels were mentioned in detail, always focusing in the torches she carried, her fasting, and her unbound hair. Only Helios saw the abduction, and he told Hecate, who then told Demeter of the unfortunate event. Zeus sent Hermes down to try and talk Demeter into allowing the grain to grow once again, but she would hear nothing of it. Only after a compromise was reached between Demeter, Persephone, and Hades was Kore/Persephone allowed to return to her mother and the grain to grow once again. Who actually fetched Persephone back is a matter of debate as well; some say Hermes, some say Hecate, and others say Demeter herself.
Kore/Persephone represents two aspects, one being the daughter or maiden of Demeter, the other being the mistress of the Underworld. Her name was also spelled Phersephone, and the Attics called her Pherrephatta. Her descent into the underworld and subsequent return is a common theme throughout many religions. While you can look at it as simply the way to explain vegetation, the cycle of Persephone's domicile (a third of each year in the Underworld, the rest with her mother) does not fit with the planting and harvesting cycles of the Mediterranean. Perhaps it is easier to relate to in the sense of the cycle of life. Because Hades represents death, it would follow that Persephone's descent to the Underworld signifies death, and her return a rebirth. Walter Burkert speaks of the myth illustrating a "double existance between the upper world and the underworld; a dimension of death is introduced into life, and a dimension of life is introduced into death."
It would be a mistake to assign Demeter the role of "mourning mother." Demeter's anger and frustration were severe enough for her to ignore the pleas of mankind while she focused on the return of her daughter. One does not get the idea that Demeter was merely sad, but terribly angry, perhaps fulfilling the role of the "terrible mother."
While Demeter is an Olympian goddess, she also retains an aspect of a Chthonic goddess because of her association through her daughter with the underworld. Because many goddesses of creation also particpate in destruction, it would make sense to see Demeter in the same way. For Persephone is not merely her daughter, but a part of herself. In fact, the two are often referred to in ancient times as the Two Goddesses or as the Demeteres. She gives the living the sustinence they need to survive, and the dead belong to her. In fact, the Athenians called the dead Demetreioi.
There are many festivals of Demeter, and they were celebrated in many parts of the ancient world. There seems to be a connection between many of her celebrations and the life of women as well, leading perhaps to a connection with the Roman Great Goddess Bona Dea. The most remarkable festival of women in ancient Greece was the Thesmophoria, which involved women making sacrifices of piglets and offering them to Demeter in an underground chasm. Demeter's festivals were not limited to women, however, for the Katagoge involved a group of men leading Kore during the processional. The Mysteries at Eleusis were the most well known, but little is known of the Mysteria for the initiates were bound to secrecy, and very few of them, if any, ever broke their vows. What transpired during the Mysteries was considered arrheton, or unspoken.
Demeter seems to be a mysterious goddess, connected with what is pure and untouched; or what the Greeks called hagnon. But even in this day it is possible to let this goddess speak to you of her mysteries, for she is as devoted to the living as many of us are devoted to her.
"Summer" ( firstname.lastname@example.org)