A long time ago in the 13th century, in the parish of Myddvai, in Carmarthenshire, there lived a widow and her only son. The widow owned a large number of sheep and cattle. Each day, her son would take some of the cattle to graze on the Black Mountain, near a small lake called Llyn-y-Van-Bach.
One day, in great wonder, the young man saw the most beautiful girl sitting on the calm surface of the lake, combing her long flowing hair. She was looking down at the water as if it were a mirror when, suddenly, feeling the young man’s gaze, she looked up.
The young man was entranced. He stretched out his hand, in which he held the barley bread and cheese he had brought from home, as if in offering. The lady, glided nearer to him, but gently refused the food. He tried to touch her, but she backed away, saying,
"Hard baked is thy bread; It is not easy to catch me."
Immediately she dived under the water and disappeared, leaving the youth to return home still thinking about the beautiful young lady who had enchanted him. His mother advised him to return with some unbaked dough. She thought there must be some spell connected with the hard baked bread which stopped the lady accepting him.
Next morning, before the sun was up, the young man was at the lake, hoping again to see the enchanting vision but there was only a stiff breeze causing ripples on the surface of the lake. A dark cloud hung over the summit of the Van.
Hours passed, the wind dropped and the day became calm. Lost in thought, the young man had failed to see that some of the cattle had moved towards the steep slope on the far side of the lake.
As he was hurrying to rescue them, the lady appeared, looking even more beautiful than before. He held out to her the unbaked bread; but she again refused, saying:
"Unbaked is thy bread! I will not have thee."
But, before she disappeared under the water, a smile played on her lips which cheered the young man.
The next day, he left home very early and, on his mother's advice, he carried some slightly baked bread. He waited impatiently for her to appear, failing to notice the rain and sunshine that came and went or the cattle wandering near the steep slope, so intent was he on seeing the enchanting young lady. He waited in vain.
The sun was setting, as he cast one last, sad look over the waters before departing home. To his astonishment, there was the maiden walking on the lake surface and, with her, several cows.
She approached the land and he rushed to meet her. A smile encouraged him to seize her hand, and she accepted the slightly baked bread he offered.
She agreed to become his wife, on one condition: that, should she ever receive from him three blows, without a cause, she would leave him forever.
Feeling more confident, now they were engaged, he let go of her hand for a moment, where upon she darted away and dived into the lake.
His grief was so great that he was about to jump in after her, when he saw three beautiful ladies and a noble looking man emerge from the lake.
The man had silver-streaked black hair but, otherwise, all the strength of youth. He told the young man he would agree to the marriage, providing the young man could distinguish which of the three ladies was the one he loved.
This was no easy task, as they were identical in every way. However, the young man noticed that one of them thrust her foot a little forward. The movement, although slight, did not escape his notice. He also saw that her sandal was tied in a slightly different way. Now he had no doubt, because he had thought before how strangely her shoe was fastened. He boldly took hold of her hand.
"You have chosen rightly," said the Father, "be kind and faithful to her and I will give her, as a dowry, as many sheep, cattle, goats, and horses, as she can count without drawing in her breath. But remember, if at any time you strike her three times without a cause, she shall return to me, with her dowry."
The marriage settlement was agreed.
The young lady counted very quickly, until her breath was exhausted. Instantly, the full number of horses, goats and cattle came out of the lake.
The young couple married, and went to live at a farm called Esgair Llaethdy, near Myddvai. Here they lived happily, prospered and had three beautiful sons.
Then, one day, while they were getting ready to attend a christening, her husband asked her to fetch one of the horses from the field.
"I will," said she, "if you will bring me my gloves which I left in our house."
He went for the gloves, then, finding she had not yet gone for the horse, he playfully slapped her shoulder with one of them, saying, "Dos, dos, go, go."
She reminded him of the terms on which she had agreed to marry him. She warned him to be more careful in the future, as he had now given her one causeless blow.
Sometime later, they attended a wedding and the guests were greatly enjoying themselves when the wife started sobbing.
Her husband, embarrassed, tapped her on the shoulder and enquired the cause of her weeping.
"For these people trouble lies ahead," she said, "and for you, unless you take care, for you have the second time struck me without cause."
The years went on, and their children grew up into very clever young men. Living in comfort and joy, the husband almost forgot that only one causeless blow would destroy his happiness. Because she loved her husband dearly, the lady warned him to be careful lest he accidently gave her a last blow, which would separate them forever.
One day they were at a funeral together. The place was full of mourning and grief but his wife appeared happy and laughing.
This so shocked her husband that he nudged her, saying, "Hush! Hush! Don't laugh."
She said that she laughed because, when people die, they leave their troubles behind.
Then her laughter died away and, with the saddest look, she rose up and left the house, saying, "The last blow has been struck, our marriage contract is broken. Farewell!"
She called her cattle and other stock together, not forgetting the oxen ploughing the field. They followed the Lady across Myddvai Mountain and disappeared beneath the waters of the lake from where they had come.
But a mother's bond is strong and one day she appeared to her sons in a cwm or valley. She promised to meet them whenever her counsel or aid was required. Taking aside her first born Rhiwallon, she told him he was to be a healer to mankind, curing all manner of diseases. Then she gave to each of them a bag, which held the key to the cure of many diseases.
True to her word, she met with her sons when they needed her help and pointed out to them the medicinal qualities of many plants and herbs. So great was their knowledge, that Rhiwallon and his sons, Cadwgan, Gruffydd, and Einion became the chief physicians of their age. In the year 1230, they wrote down their knowledge in a book, known as the 'Red Book of Hergest'.
The book can be found in the Welsh School Library, in Gray's Inn Lane. The Cwm where Rhiwallon met his mother is now called Cwm Meddygon or Physicians' Combe. And if you still have doubts about what you have heard, travel to the lake and you will see, in several places, a furrow in the ground. It is the furrow made by the oxen's plough, as they returned to the lake. And there it remains to this day, as a testimony of the truth of this tale.