So the sheath of Excalibur was lost, and that was a grievous thing for King Arthur in after time, as you may some time read.
Queen Morgana exercises her magic.
Now after Queen Morgana le Fay had thus thrown the sheath of Excalibur into the lake, she went on a little farther to where was a very lonely place with a great many rocks and stones lying about upon the ground. And when she had come to that place she exercised very potent spells of magic that Merlin had taught her. So, by means of those spells, she transformed herself and all of her Court and all of their horses into large round stones of divers sizes.
Then in a little while came King Arthur to that place with his knights and esquires, and he was exceedingly heavy of heart, for he had beheld from a great distance how Queen Morgana le Fay had thrown the sheath of Excalibur into that lake.
Now when the King and his Court had come to that spot the damsel Vivien called out upon him to stop and she said to him, “Lord, dost thou behold all those great round stones?” “Yea,” said the King, “I do see them.” Then Vivien said, “Lo! those stones are Queen Morgana le Fay and the Court who were with her. For this magic that she hath done to change herself and them into stones was a certain thing that Merlin had taught her. Now I myself know that magic, and I also know how to remove that magic at my will. Wherefore, if thou wilt promise to immediately punish that wicked woman for all her treason by depriving her of her life, then will I bring her back unto her true shape again so that thou mayst have her in thy power.”
King Arthur chideth Vivien.
Then King Arthur looked upon Vivien with great displeasure, and he said, “Damsel, thou hast a cruel heart! Thou thyself hast suffered no injury at the hands of Queen Morgana; wherefore, then, wouldst thou have me slay her? Now, but for all thou hast done for me I would be very much affronted with thee. As for her, I forgive her all of this, and I shall forgive her again and again and yet again if she sin against me. For her mother was my mother, and the blood which flows in her veins and in my veins cometh from the same fountain-head, wherefore I will do no evil thing against her. Let us return again whence we came.”
Then Vivien looked upon King Arthur very bitterly, and she laughed with great scorn, and said, “Thou art both a fool and a dotard,” and therewith she vanished from the sight of all.
And after that, because King Arthur had rebuked her for her wickedness in the presence of others, she hated him even more than Morgana le Fay had hated him.
Some time after that, King Arthur heard how Merlin had been beguiled by Vivien, and he sorrowed with great bitterness that Merlin was lost unto the world in that wise.