Oisín (Oisín)

Three hundred years in the land of the young, and the one condition he broke.

Oisín was the son of Fionn mac Cumhaill and a poet of the Fianna. His name means little deer, which belongs to the story of his mother Sadhbh, who was under a spell that made her a deer.

Niamh Chinn Óir, Niamh of the golden hair, came riding over the sea on a white horse and asked him to go with her to Tír na nÓg, the land of the young. He went. They lived there in a country without sickness or age, and he was happy, and after what felt like three years he wanted to see his father and the Fianna again.

Niamh gave him the horse and one condition: whatever happened, he must not let his feet touch the ground of Ireland.

He rode back to find the ground changed. The forts were empty, the Fianna were a story, and three hundred years had gone. In most versions he comes on men struggling to shift a stone, far smaller men than he remembers, and leans down to help them, and the saddle girth breaks. The instant he touches the earth the three centuries land on him at once and he is an old, old man in the dirt.

What happens next is the strangest part. The tradition keeps him alive long enough to meet Saint Patrick, and a whole body of literature, the Agallamh na Seanórach, is the two of them in conversation: the last pagan telling the new faith what has been lost, and Patrick writing it down.