Demeter and Persephone - Ancient Greek myth

Demeter loved her little daughter, Persephone. They played together in the fields almost every day. As Persephone smiled up at her mother, Demeter's heart swelled with happiness, and the crops grew high and healthy. Flowers tumbled everywhere. As time passed, Persephone grew into a lovely goddess. That's when the trouble started.
Hades, the king of the underworld, was a gloomy fellow. He normally hung out in the Underworld.
One day, Hades felt restless. He decided to take his three-headed dog out for a chariot ride. Cerberus, his dog, usually stood guard at the gate to Underworld. But Hades gave his pup a break now and then. He scooped up Cerberus, and left a couple of spirits in charge instead.

Hades flew his chariot up to earth. Cerberus leaped out of the chariot and ran around, sniffing flowers with all three of his heads. The dog ran up to a lovely young woman, the goddess Persephone. Some people might have been startled if a three-headed dog came tearing up. But Persephone only laughed and scratched his heads.

Hades loved that old dog. He watched his dog playing happily with Persephone. He heard Persephone's delighted laugh. Hades fell deeply in love. Before anyone could stop him, he grabbed his niece, his dog, and his chariot and dove deep into the darkest depths of the Underworld.

Hades locked Persephone in a beautifully decorated room in the Hall of Hades. He brought her all kinds of delicious food. Persephone refused to eat. She had heard if you ate anything in Hades, you could never leave. She had every intention of leaving as soon as she could figure out how to do so.
Over a week went by. Finally, in desperate hunger, Persephone ate six pomegranate seeds. She promptly burst into tears.

She was not the only one crying. Demeter, her mother, missed her daughter terribly. She did not care if the crops died. She did not care about anything except finding her daughter. No one knows who told Zeus about it, but it was clear this could not go on. Zeus sent his son Hermes to work a deal with Hades.

This was the deal Hermes worked out: If Persephone would marry Hades, she would live as queen of the Underworld for six months each winter. In the spring, Persephone would return to earth and live there for six months. No one especially liked the deal, but everyone finally agreed.

Every spring, Demeter makes sure flowers are blooming and crops are growing and the fields are green with welcome. Every fall, when Persephone returns to the underworld, Demeter ignores the crops and flowers and lets them die. Each spring, Demeter brings everything to life again, ready to welcome her daughter's return.

To the ancient Greeks, that was the reason for seasons - winter, spring, summer, fall.