Demeter was one of the six original Olympian gods, daughter of Rhea and Chronos. When the gods split the kingdoms of Earth amongst them, Demeter chose the harvest as her domain. Her blessing made the Earth rich and fertile, but when she withdrew her blessing, it would become hard and cold, barren. Her moods also affected the weather and sometimes the earth itself.
Demeter had a daughter, who she loved very much, called Persephone. Persephone was a lovely young lady, so beautiful that the nymphs of the forest would spend all day weaving flowers in her hair, and young men would travel from all over just to gaze upon her face. But Demeter didn't want to let her daughter go, and zealously drove the suitors away from her daughter.
One day Persephone was gathering flowers to weave into a crown for her mother when suddenly something caught her eye. The fairest and most lovely flower she had ever seen greeted her eye. She was irresistably drawn towards it, but just as she bent down to pick it, there was a sudden thundering sound and Hades' chariot swooped out of the sky. Hades himself leaned out and grabbed Persephone, retreating with her to his underworld kingdom.
Hades had seen Persephone when he was spying on the world of the mortals and had instantly fell madly in love with her. But his advances were scorned by Demeter, who flatly refused to let him take her as his bride. So, he had planted the flower knowing she would be unable to resist it, and so, when her fingers reached out and brushed the stem, he appeared and took her back to the world deep beneath.
Persephone was horrified at Hades' actions, and had no desire to stay with him. So, when he offered her drinks, or offered a couch to lay on, she declined, knowing to accept either would doom her to stay in the Underworld forever. But Hades' kind words and gentle overtures eventually found a way into her heart, and she found herself growing fond of him. But her longing to be with her mother was just as great.
Demeter, upon discovering the disappearance of her daughter, roamed the Earth searching for her, and while she roamed, her blessing withdrew from the Earth and it became barren and cold. And so she wandered, until the pleas of the mortals drew Zeus' attention, and he called to Demeter, asking her what was the matter, why had she taken her blessing from the Earth?
"My daughter has been stolen from me by Hades," Demeter replied. "And I will not return my blessing until my daughter is returned to me." Zeus frowned, and turned to Hades.
"Have you done this hideous thing brother? And Why?"
"Yes, I have taken Persephone as my wife. But she cannot return to the surface. For, while she was here, a servant offered her a pomegrant, and she ate six of the twelve seeds inside. Therefore, she must stay with me." Hades replied, but Demeter would not accept this.
"Then if my daughter will not be returned to me, my heart will be as barren as this land will become for I will not bless it." Demeter in turn replied. Zeus retreated to his high throne and sat in throught for several days before calling Demeter and Hades to him.
"This is my decision." He rumbled, "And as King of Olympus it will be obeyed. Since Persephone did eat while she was in the Underworld, she must stay there. However, since she only ate half of the twelve seeds, she shall spend half of the year in the Underworld with her husband. But the other half of the year she will spend with her mother on the surface. This is my desicion."
And his desicion stood firm. Persephone spent half the year ruling over the Underworld with her husband, Hades, whom she had grown to love dearly as her own mother. And while she was with Hades, her mother would wander the topside, and wouldn't bless the Earth, and it would be barren and cold. But when Persephone rejoined her mother, Demeter would once again bestow her blessing upon the Earth, and it would warm and the crops would grow and flourish and there would be life.
This myth explains the seasons as well as serves as an example of Zeus' wisdom.
