Meilyr was visiting the annual fair when his eye was caught by a young woman whose charms seemed to him incomparable. To his delight he managed to engage her in conversation and they spent some time together at the fair. He asked her if she would meet him again and she agreed. So they met at the trysting tree and walked together in the forest. Then lied down together on the soft moss on a flat rock above the flowing stream. There Meilyr took her in his arms. At first she warned him that no good would come of it, but he persisted so she allowed him to continue. As they lay together - fulfilled - on the moss she turned in his arms into an old crone of extreme ugliness with warts and hair sprouting from her nose. She left him then but said they might meet again in her own country.
For some time after this Meilyr lost his wits and wandered the land as a deranged vagrant. Eventually he recovered and resumed his former life. But although he seemed to others to be restored to what he had been, he found that he could see things that others could not see and he had the power too see events before they happened. And he saw his lover again, though not as he had seen her before, as she passed through the veil between the worlds and spoke to him so that he found, in repeating her words, that his speech was inspired. So he became a great poet, and a seer, and gained a reputation as a wise man, and a possessor of cunning arts.
All for the love of his lady.
Giraldus Cambrensis told a version of this tale in his twelfth century Journey Through Wales summarized HERE