Then he asked Merlin, ‘Tell me how the young lady could pass over the water with dry feet.”

Merlin began to laugh and said, “My lord, it was not as you saw, but I’ll tell you how it is with the lake, for I know it well. The truth is that there is a large and marvelously deep lake. In the middle of this lake there is a rock, where there are beautiful, rich houses and large, marvelous palaces, but they are so entirely enclosed with spells that no one outside can see them, unless he is from that place. Where you saw the young lady walk, there is no water; rather, there is a wooden bridge that no one can see. Those who go there cross on the bridge, for they see it, although others don’t.”

Post-Vulgate Merlin