Long ago, on an isle of emerald green, surrounded by a sea of azure blue, there lived a young man named Oisin.
Oisin liked to explore the moors with the Fianna, ancient warrior-hunters.
One day, when Oisin and the Fianna were out hunting, they saw an extraordinary sight. It was a beautiful young woman with long red hair, riding on a spirited white mare. The sun glistened off the maiden's hair, casting a magical golden light.
The mare's movements were so fluid that she appeared to float across the ground. As her rider brought her to a stop before the group, the horse's hooves struck at the field stones impatiently, sending small sparks into the air.
"My name is Niamh," the woman said, in a voice that sounded like the music of a harp. "My father is the king of Tir Na Nog."
Oisin stepped forward from the group of hunters to welcome the rider. As his eyes met Niamh's, they fell in love.
"Come with me to Tir Na Nog," Niamh pleaded to her new found love. After only a moment's hesitation, Oisin swung up behind Niamh onto the white horse.
Together, they crossed the sea to Tir Na Nog.
Having grown up on the Emerald Isle, Oisin would never have believed that a more beautiful land existed. But, as he gazed upon Tir Na Nog, he was stunned by the beauty around him.
In this magical land, Niamh and Oisin built a life together. They spent each day exploring Tir Na Nog with the white mare. Niamh and Oisin's love grew deeper as Niamh shared the beauty of her enchanted homeland.
300 years passed as though it were but a single day. No one in Tir Na Nog ever grew old or fell sick. They lived in endless, youthful moments filled with happiness.
In spite of the beauty of the land and the deep love that Niamh and Oisin shared for each other, a small part of Oisin's soul knew loneliness.
Such feelings were unheard of in Tir Na Nog. But in spite of her efforts, Niamh was unable to ease Oisin's loneliness.
So, when Oisin came to Niamh and told her of his desire to return to Ireland to see his family and the Fianna again, she could not hold him back.
"All right," said Niamh. "Return to Ireland on the back of the white mare. But my dear, your foot must not touch the soil of Ireland!"
Immediately Oisin rode the white horse back across the sea to the land of his birth.
But, as soon as the mare's hooves touched Ireland's soil, Oisin realized how much the land had changed. Oisin's family and friends had long passed away. Their grand castle was over grown with ivy.
Oisin was so caught up in his quest to find his family and his grief at their loss, that he forgot to care for the beautiful white horse. In spite of her hunger and fatigue she continued to respond to her rider.
Finally, with a sad heart, Oisin turned the mare back toward the sea to return to Tir Na Nog.
Approaching the sea, he came upon a group of men working in a field. As the mare reached the group, her fatigue caused her to stumble. Her hoof hit a stone. Oisin bent down to pick up the rock, planning to take it to Tir Na Nog. He was sure that it would ease his sadness to carry a piece of Ireland back with him.
But as his hand grasped the stone, Oisin lost his balance and fell to the ground.
Within moments, Oisin aged 300 years.
Without her rider, the mare reared up and rushed into the ocean, returning to Tir Na Nog and her beloved Niamh.
When the men in the field witnessed this, they were amazed. Not only had they seen a young man age before their eyes, they had also seen a tired old plow horse transformed into a beautiful silver-white mare, who raced into the sea.
The men went to Oisin's aid and carried him to St. Patrick.
When Oisin met St. Patrick, he told Patrick of the his family and the Fianna, who had disappeared from Ireland almost 300 years before. Then he told St. Patrick of Niamh and the magical land of Tir Na Nog.
As Oisin ended his story, a great weariness swept over him and he closed his eyes in eternal slumber.
Even to this day, the fishermen and lighthouse keepers still tell of foggy nights when the moon is full, and they see a shimmering white horse dancing in the waves along the shores of Ireland. Some say that the red-haired maiden who rides the horse still searches for Oisin.