Demeter Causes Winter

Demeter, the Goddess of the Harvest, had a daughter named Persephone. One day Persephone was in the field when she pulled at a plant – and was surprised when the whole plant came out, leaving a hole in the ground. Then, suddenly, out of this hole came Hades, the God of the Underworld. Hades took Persephone with him, back down into the ground.
Demeter looked for her daughter, but could not find her. As she grieved, so there was no harvest: the plants began to die, and no new ones were born. As the plants died, so people and animals began to starve. Seeing the world in such a state, Zeus sent Hermes, his messenger, to talk to Hades.
‘I can only let her go back to her world if she has not eaten anything from my world, but she has eaten four pomegranate seeds.’
A deal was therefore struck: Persephone would leave the underworld, back to her mother, but return to Hades each year, staying a month for each of the seeds she had eaten. It is, therefore, during these four months that Demeter, missing her daughter, makes nothing grow.