"And then, soon after, the Lady of the Lake [Nimue] and Merlin departed; and by the way as they went Merlin showed her many wonders, and came into Cornwall.
…And so, upon a time, it happened that Merlin showed to her a rock where there was a great wonder, and wrought by enchantment, which went under a stone. So, by her subtle craft and working, she made Merlin to go under the stone to let her wit of the marvels there; but she wrought so there for him, that he came out never, for all the craft that he could do: and so she departed, and left Merlin."
The Noble and Joyous History of King Arthur: the Book of Morgan le Fay Sir Thomas Malory
* Dulac returned to this theme for The American Weekly in March 1940 (see Colin White)