Once upon a time, there was no such thing as winter. This distressed skiing enthusiasts but pleased everyone else since snowplows hadn’t been invented yet.
Meanwhile Demeter, the goddess of the harvest, wandered around the earth wearing flimsy gauze dresses and making the crops grow. Somewhere along the line, she and Zeus had a daughter named Persephone.
Persephone was lovely and Hades, the god of the underworld noticed. Hades invited Persephone to leave the lovely topsoil and dwell (and by “dwell” I mean dwell) with him in the underworld.
Persephone said thanks but no thanks. You remember that gods don’t like being told no, right? Hades lifted an eyebrow and said, “No?”
Persephone raised both eyebrows and repeated herself. Hades frowned, picked Persephone up, threw her over his shoulder, and took her back to the underworld.
Persephone was not happy. Demeter (her mother) was even less happy. Demeter raged, she ranted, and then she went into a full-fledged funk.
Have you ever seen a goddess funk? Not pretty. And when Demeter funked, the whole world funked with her. Plants turned brown, crops withered, and people went hungry.
Now Zeus was pretty good at ignoring things he didn’t care about, but with the whole world hungry sacrifices to the gods weren’t being made and that got his attention.
Zeus went to talk sense into Hades (and by “sense” I mean tried to talk him into giving Persephone back). Hades refused. They argued. Finally, they consulted the rule book.
According to the Rules, if a person eats while in the underworld, they are stuck there forever (keep that in mind during your travels).
They quickly scoured the various meals Persephone had refused to eat—and discovered that she had eaten exactly 6 pomegranate seeds. (Hey—sometimes a girl has to snack.)
Zeus therefore decreed (being the chief number one honcho god he got to do the decreeing) that Persephone would be returned to her mother for 6 months of the year, but for the other six (one for each aril) she would have to return to Hades and the underworld.
Therefore, for six months of the year the earth is warm and happy. Plants bloom and crops are bountiful while Demeter is happy having her daughter at home. The other six months, Persephone returns to the underworld and Demeter returns to her snit. The earth is cold and barren. You might think Demeter would have gotten over it by now, but you’d be wrong.