Posted from the book “Wonder Tales from Scottish Myth and Legend" by Donald Alexander Mackenzie - Illustrations by John Duncan - Frederick A Stokes Co., New York -  - (Obtain this full work and many more backups by clicking here!)
Thomas Learmonth (c. 1220 – c. 1298; also spelled Learmount, Learmont, or Learmounth), better known as Thomas the Rhymer or True Thomas, was a 13th century Scottish laird and reputed prophet from Earlston (then called "Erceldoune"). He is also the protagonist of the ballad "Thomas the Rhymer" (Child Ballad number 37). He is also the probable source of the legend of Tam Lin.
The Story of Thomas the Rhymer
At the beginning of each summer, when the milk-white hawthorn is in bloom, anointing the air with its sweet odour, and miles and miles of golden whin adorn the glens and hill-slopes, the fairies come forth in grand procession, headed by the Fairy Queen. They are mounted on little white horses, and when on a night of clear soft moonlight the people hear the clatter of many hoofs, the jingling of bridles, and the sound of laughter and sweet music coming sweetly down the wind, they whisper one to another: "’Tis the Fairy Folks' Raid", or "Here come the Riders of the Shee".
The Fairy Queen, who rides in front, is gowned in grass-green silk, and wears over her shoulders a mantle of green velvet adorned with silver spangles. She is of great beauty. Her eyes are like wood violets, her teeth like pearls, her brow and neck are swan-white, and her cheeks bloom like ripe apples. Her long clustering hair of rich auburn gold which falls over her shoulders and
down her back, is bound round about with a snood that glints with star-like gems, and there is one great flashing jewel above her brow. On each lock of her horse's mane hang sweet-toned silver bells that tinkle merrily as she rides on.
The riders who follow her in couples are likewise clad in green, and wear little red caps bright as the flaming poppies in waving fields of yellow barley. Their horses' manes are hung with silver whistles upon which the soft winds play. Some fairies twang harps of gold, some make sweet music on oaten pipes, and some sing with birdlike voices in the moonlight. When song and music cease, they chat and laugh merrily as they ride on their way. Over hills and down glens they go, but no hoof-mark is left by their horses. So lightly do the little white creatures trot that not a grass blade is broken by their tread, nor is the honey-dew spilled from blue harebells and yellow buttercups. Sometimes the fairies ride over tree-tops or through the air on eddies of western wind. The Riders of the Shee always come from the west.
When the Summer Fairy Raid is coming, the people hang branches of rowan over their doors and round their rooms, and when the Winter Raid is coming they hang up holly and mistletoe as protection from attack; for sometimes the fairies steal pretty children while they lie fast asleep, and carry them off to Fairyland, and sometimes they lure away pipers and bards, and women who have sweet singing voices.
Once there was a great bard who was called Thomas the Rhymer. He lived at Ercildoune (Earlston), in Berwickshire, during the thirteenth century. It is told that he vanished for seven years, and that when he reappeared he had the gift of prophecy. Because he was able to foretell events, he was given the name of True Thomas.
All through Scotland, from the Cheviot Hills to the Pentland Firth, the story of Thomas the Rhymer has long been known.
During his seven years' absence from home be is said to have dwelt in fairyland. One evening, so runs the tale, he was walking alone on the banks of Leader Water when he saw riding towards him the Fairy Queen on her milk-white steed, the silver bells tinkling on its mane, and the silver bridle jingling sweet and clear. He was amazed at her beauty, and thinking she was the Queen of Heaven, bared his head and knelt before her as she dismounted, saying: "All hail, mighty Queen of Heaven! I have never before seen your equal."
Said the green-clad lady: "Ah! Thomas, you have named me wrongly. I am the Queen of Fairyland, and have come to visit you."
"What seek you with me?" Thomas asked.
Said the Fairy Queen: "You must hasten at once to Fairyland, and serve me there for seven years."
Then she laid a spell upon him, and he had to obey her will. She mounted her milk-white steed and Thomas mounted behind her, and they rode off together. They crossed the Leader Water, and the horse went swifter than the wind over hill and dale until a great wide desert was reached. No house nor human being could be seen anywhere. East and west, north and south, the level desert stretched as far as eye could see. They rode on and on until at length the Fairy Queen spoke, and said: "Dismount, O Thomas, and I shall show you three wonders."
Thomas dismounted and the Fairy Queen dismounted also. Said she: "Look, yonder is a narrow road full of thorns and briers. That is the path to Heaven. Yonder is a broad highway which runs across a lily lea. That is the path of wickedness. Yonder is another road. It twines round the hill-side towards the west. That is the way to Fairyland, and you and I must ride thither."
Again she mounted her milk-white steed and Thomas mounted behind. They rode on and on, crossing many rivers. Nor sun or moon could be seen nor any stars, and in the silence and thick
darkness they heard the deep voice of the roaring sea.
At length a light appeared in front of them, which grew larger and brighter as they rode on. Then Thomas saw a beautiful country. The horse halted and he found himself in the midst of a green garden. When they had dismounted, the Fairy Queen plucked an apple and gave it to, Thomas, saying: "This is your reward for coming with me. After you have eaten of it you will have power to speak truly of coming events, and men will know you as 'True Thomas'."
Thomas ate the apple and then followed the queen to her palace. He was given clothing of green silk and shoes of green velvet, and he dwelt among the fairies for seven years. The time passed so quickly that the seven years seemed no longer than seven hours.
After his return to Ercildoune, where he lived in a castle, Thomas made many songs and ballads and pronounced in rhyme many prophecies. He travelled up and down the country, and wherever he went he foretold events, some of which took place while yet he lived among men, but others did not happen until long years afterwards. There are still some prophecies which are as yet unfulfilled.
It is said that when Thomas was an old man the Fairy Queen returned for him. One day, as he stood chatting with knights and ladies, she rode from the river-side and called: "True Thomas, your time has come."
Thomas cried to his friends: "Farewell, all of you, I shall return no more." Then he mounted the milk-white steed behind the Fairy Queen, and galloped across the ford. Several knights leapt into their saddles and followed the Rider of the Shee, but when they reached the opposite bank of the river they could see naught of Thomas and the Fairy Queen.
It is said that Thomas still dwells in Fairyland, and that he goes about among the Riders of the Shee when they come forth at the beginning of each summer. Those who have seen him ride past tell that he looks very old, and that his hair and long beard are white as driven snow. At other times he goes about invisible, except when he attends a market to buy horses for a fairy army which is to take part in a great battle. He drives the horses to Fairyland and keeps them there. When he has collected a sufficient number, it is told, he will return again to wage war against the invaders of his country, whom he will defeat on the banks of the Clyde.
Thomas wanders far and wide through Scotland. He has been seen, folks have told, riding out of a fairy dwelling below Eildon Hills, from another fairy dwelling below Dumbuck Hill, near Dumbarton, and from a third fairy dwelling below the boat-shaped mound of Tom-na-hurich at Inverness.
Once a man who climbed Dumbuck Hill came to an open door and entered through it. In a dim chamber he saw a little old man resting on his elbow, who spoke to him and said: "Has the time come?"
The man was stricken with fear and fled away. When he pressed through the doorway, the door shut behind him, and turf closed over it.