Cited: "It is not a little confusing to find, when you sit down to write of a picture town of France, that you must write at the same time of a little town in England, yet such is the necessity imposed by a curious geographical coincidence.
It has been said Nature never repeats herself, and that all her masterpieces are unique. Nevertheless, she has very nearly reproduced on the northern shore of the English Channel the wonderful Mont St. Michel that, upon the southern coast, stands as a monument marking the beginning of the boundary line between Brittany and Normandy, two of the most charming provinces of France.
The French Mont St. Michel is an isolated cone of rock, three hundred feet in height, that rises from the sea a half-mile or so from shore. Of almost the same circumference and of practically the same general appearance, the English St. Michael's Mount lifts itself half a mile off the Cornwall coast to a height but little less. The ancient legends of the land that now is France tell us that early in the Eighth Century St. Michael appeared in a vision to the Bishop of the Diocese embracing the Mount, and commanded that on that Mount he build a church, of which Michael should be the patron saint. The old-time folklore of Cornwall has precisely the same tradition, coming from a somewhat earlier period, concerning the St. Michael's Mount. On the summit of each rose a Gothic church in honor of this Saint. Later, a castle appeared on one and fortifications on the other. On each humble fishers built their villages, protected on the English rock by the castle, on the other by the walls. Around both sweep the Channel tides."
More about the Island twins of Mount St. Michael in Cornwall and Mont St. Michel in Normandy