I like to tell this story to young people on a hike to Arethusa Falls, withholding the name of the wood-nymph-turned-fountain until the very end.
Demeter was the goddess of the soil, and of growth and produce and agriculture. Her Roman name, Ceres, is where we get our word "cereal," because she was also the goddess of an important part of this nutritious breakfast.
Demeter had a beautiful daughter named Persephone, whose father was Nereus, the god of the ocean. Persephone loved to run and play in the fields and forests. One day she was picking flowers with her sisters, the Nereids, when suddenly they were attacked by Hades, the god of the underworld. Hades, enamored of Persephone, took her captive to become his queen.
When Demeter went looking for her daughter, Persephone was nowhere to be seen, and nobody would tell Demeter where she was. Most did not know, and the Nereids were afraid to tell, for fear of angering Hades. (Demeter would later turn the Nereids into Sirens, as punishment for their silence.)
Demeter became convinced that the earth had swallowed her daughter, and she cursed the soil. The ground became hard as stone, the trees ceased to bear fruit and lost their leaves, and the fields did not yield their crops. The rain fell as frozen snow, and the earth lay dying. Still, Demeter searched over the whole world for her lost daughter, until she came back to Sicily, where she had started.
There, a fountain braved the wrath of Hades to tell Demeter where Persephone was. She told her story.
This fountain had been a wood nymph, devoted to Artemis, and like Artemis, devoted to hunting and sworn to chastity. She would never marry, nor have anything to do with any man. One day, hot and tired from the hunt, she decided to take a bath in the River Alpheus. As she played and swam, she became aware of a presence coming up from the depths of the river. She ran back into the forest, but the god of the river chased after her, declaring his love for her.
The wood nymph outran Alpheus for a time, but she soon grew tired. As Alpheus was about to catch up with her, the wood nymph called out to her patron, Artemis, to save her. Artemis, pleased to aid one of her devotees, turned the wood nymph into a fountain.
Not to be denied, the river god Alpheus began moving the course of his river to mingle his waters with the waters of this fountain, and so to have her. Again, the wood-nymph-turned-fountain cried out to Artemis, and the goddess opened up a huge cavern in the earth. The fountain flowed into the cavern, passed through the underworld, and returned to the surface in Sicily.
But as she passed through the realm of Hades, she saw Persephone seated on his throne as queen of the underworld. She looked sad, but no longer distressed about having been taken captive. And so, this wood-nymph-turned-fountain was able to tell Demeter what had become of her daughter.
Demeter pleaded with Zeus to order Hades to release her daughter back into the world of light. Zeus agreed, but only on condition that Persephone had not eaten any food while she had been in the realm of Hades. Unfortunately, Hades knew that anyone who had taken the food of the netherworld would be forbidden to return to the earth, so he had given Persephone a pomegranate, and she ate four of its seeds.
Eventually, a compromise was reached. Persephone would be permitted to stay in the surface world with her mother for eight months of each year, but would return to be queen of the underworld for four months of the year, one for each seed she had eaten.
That is why, for eight months of each year, the earth is fertile and yields its fruits and crops, but for four months of the year, the ground is hard as stone, the rain falls as frozen snow, and no green thing grows.
And what was the name of this wood-nymph-turned-fountain who told Demeter what had happened to Persephone? Arethusa!
Epilogue 1. Arethusa Falls, in Crawford Notch State Park in New Hampshire's White Mountains, is not directly named for the fountain Arethusa in Sicily. It is named for a genus of orchid which once lived in the area but is now locally extinct. The humidity-loving orchid was named for the fountain in Sicily.
Epilogue 2. Think I don't know my mythology? The story as presented here is pretty close to Bullfinch's version, though I have used the Greek names while Bullfinch prefers the Roman names. "Demeter and Persephone" just sounds better to me than "Ceres and Proserpine." And nearly every other aspect of this story has some different twist in some other source. Most notably, many versions have the River Alpheus (modern name Alfeios) flowing under the sea and emerging in Sicily as the fountain Arethusa, so that Alpheus got his way after all.