One day, as Finn and his companions and dogs were returning from the chase to their dun on the Hill of Allen, a beautiful fawn started up on their path, and the chase swept after her, she taking the way which led to their home. Soon all the pursuers were left far behind save only Finn himself and his two hounds Bran and Skolawn. Now these hounds were of strange breed; for Tyren, sister to Murna, the mother of Finn, had been changed into a hound by the enchantment of a woman of the Fairy Folk, who loved Tyren's husband Ullan; and the two hounds of Finn were the children of Tyren, born to her in that shape. Of all hounds in Ireland they were the best, and Finn loved them much, so that it was said he wept but twice in his life, and once was for the death of Bran.
At last, as the chase went on down a valley-side, Finn saw the fawn stop and lie down, while the two hounds began to play round her, and to lick her face and limbs. So he gave commandment that none should hurt her, and she followed them to the Dun of Allen, playing with the hounds as she went.
The same night Finn awoke and saw standing by his bed the fairest woman his eyes had ever beheld.
"I am Saba, O Finn," she said, "and I was the fawn you chased today. Because I would not give my love to the Druid of the Fairy Folk, who is named the Dark, he put that shape upon me by his sorceries, and I have borne it these three years. But a slave of his, pitying me, once revealed to me that if I could win to your great Dun of Allen, O Finn, I should be safe from all enchantments, and my natural shape would come to me again. But I feared to be torn in pieces by your dogs, or wounded by your hunters, till at last I let If be overtaken by you alone and by Bran and Skolawn, who have the nature of man and would do me no hurt." "Have no fear, maiden," said Finn, "the Fianna, are free, and our gucst-friends are free; here is none who shall put compulsion on you here."
So Saba dwelt with Finn, and he made her his wife and so deep was his love for her that neither the battle nor the chase had any delight for him, and for months he never left her side. She also loved him as deeply, and their joy in each other was like that of the Immortals in the Land of Youth. But at last word came to Finn that the warships of the Northmen were in the Bay of Dublin, and he summoned his heroes to the fight. "For," said he to Saba, "the men of Erin give us tribute and hospitality to defend them from the foreigner, and it were shame to take it from them and not to give that to which we, on our side. are pledged." And he called to mind that great saying Goll mac Morna when they were once sore bestead by a mighty host. "A man," said Goll, "lives after his life, but not after his honour."
Seven days was Finn absent, and, he drove the Northmen from the shores of Erin. But on the eighth day he returned, and when he entered his dun he saw trouble in the eyes of his men, and of their fair womenfolk, and Saba was not on the rampart expecting his return. So he bade them tell him what had chanced, and they said:
"While you, our father and lord, went afar off smiting the foreigner, and Saba looking ever down the pass for your return, we saw one day as it were the likeness of you approaching, and Bran and Skolawn at your heels. And we seemed also to hear the notes of the Fian hunting-call blown on the wind. Then Saba hastened to the great gate, and we could not stay her, so eager was she to rush to the phantom. But when she came near she halted and gave a loud and bitter cry, and the shape of you smote her with a hazel wand, and lo, there was no woman there any more, but a deer. Then those hounds chased it, and ever as it strove to reach again the gate of the dun they turned back. We all now seized what arms we could ar d ran out to drive away the enchanter, but when we reached the place there was nothing to be seen, only still we heard the rushing of flying feet and the baying of dogs, and one thought it came from here, and another from there, till at last the uproar died away and all was still What we could do, O Finn, we did; Saba is gone."
Finn then struck his hand on his breast, but spoke no word, and he went to his own chamber. No man saw him for the rest of that day, nor for the day after. Then he came forth, and ordered the matters of the Fianna as of old, but for seven years thereafter he went searching for Saba through every remote glen and dark forest and cavern of Ireland, and he would take no hounds with him save Bran and Skolawn. But at last he renounced all hope of finding her again, and went hunting as of old.
One day as he was following the chase on Ben Bulban, in Sligo, he heard the musical bay of the dogs change of a sudden to a fierce growling and yelping, as though they were in combat with some beast, and running hastily up he and his men beheld, under a great tree, a naked boy with long hair, and around him the hounds struggling to seize him, but Bran and Skolawn fighting, with them and keeping them off. And the lad was tall and shapely, and as the heroes gathered round he gazed undauntedly on them, never heeding the rout of dogs at his feet. The Fians beat off the dogs and brought the lad home with them, and Finn was very silent and continually searched the lad's countenance with his eyes. In time the use of speech came to him, and the story that he told was this:
He had known no father, and no mother save a gentle hind, with whom he lived in a most green and pleasant valley shut in on every side by towering cliffs that could not be scaled or by deep chasms in the earth. In the summer he lived on fruits and suchlike, and in the winter store of provisions was laid for him in a cave. And there came to them sometimes a tall, dark-visaged man, who spoke to his mother, now tenderly, and now in loud menace, but she always shrank away in fear, and the man departed in anger. At last there came a day when the dark man spoke very long with his mother in all tones of entreaty and of tenderness and of rage, but she would still keep aloof and give no sign save of fear and abhorrence. Then at length the dark man drew near and smote her with a hazel wand; and with that he turned and went his way, but she this time followed him, still looking back at her son and piteously complaining. And he, when he strove to follow, found himself unable to move a limb; and crying out with rage and desolation he fell to the earth, and his senses left him.
When he came to himself he was on the mountain-side on Ben Bulban, where he remained some days, searching for that green and hidden valley, which he never found again. And after a while the dogs found him; but of the hind his mother and of the Dark Druid there is no man knows the end.
Finn called his name Oisin (Little Fawn), and he became a warrior of fame, but far more famous for the songs and tales that he made; so that of all things to this day that are told of the Fianna of Erin men are wont to say, "Thus sang the bard Oisin, son of Finn."