Although the title of this tale refers to a glaistig, Maclachlan himself addresses her as a Chailleach, and the confusion between the two beings is common. This is a fascinating tale in some respects, clearly referencing the tradition of Fionn and how he came to possess his powers, as well as the common belief that such powers are gifted to people by the daoine sìth or other kinds of Otherworldly figures like the Cailleach.
The first of the MacLachlans of Ardnamurchan lived in Glenahurich. In his herd of horses he had a fine grey mare, whose first foal he wished to keep. But the Glastig frequenting the rocky sides of a neighbouring ravine or waterfall knew this; and because she hated him as an intruder in the place, she resolved to disappoint him.
As soon as the foal was born, she took it and thrust it into a hole opening over an underground stream, in which it was drowned. On the following day MacLachlan found the foal dead in the hole, but thought that it had fallen in accidentally. Next year the same thing happened, the second foal being found dead in the same hole, and in the same underground stream. His suspicion was now aroused, and so he resolved to watch the mare next summer at foaling time.
When the season arrived, he went one day to the hill to see the mare; but the Glastig was there before him, and was busy pushing the third foal through the hole into the stream underneath. He knew well how to defend himself from fairy influence; and, therefore, he seized the Glastig in his arms, and with a great effort succeeded at last in throwing her down.
“Your death is over you, Carlin,” said he, as he stood over her. ” My ransom is mine own,” she replied. “What ransom wilt thou give me?” said he.
“The vision of the two worlds to thyself and prosperity to thee and to thy descendants after thee.” On these terms he let her go.
Some time after, being in the Braes of Lochaber, he took his rod, and went to the river Spean to fish. With the first cast he hooked a fine fish, which he landed on the river bank. Being hungry, he kindled a fire at the river side, and placed the fish upon it.
Soon afterwards he happened to press with his finger a blister which rose on the upperside of the fish. The heat burnt his finger so badly that he put it into his mouth to cool. No sooner had he done this than he obtained the vision of the two worlds, or, in other words, the second sight. The first part of the Glastig’s promise was then fulfilled, and it is said that the other part was fulfilled afterwards.