Lough Foyle means the borrowed lake, for in old times there were
two weird sisters dwelling beyond the Shannon, who were skilled in
necromancy. And the elder sister said to the younger—
“Give me the loan of your silver lake, for I have none; and I promise
to restore it to you next Monday.”
So the younger, being good-natured, rolled up the lake in a sheet and
despatched it over hills and dales to her sister. But when the time
came for return, the elder sister, being deceitful and cunning, made
answer to the messenger sent for it—
“Truly, I said Monday, but I meant the Day of Judgment. So I shall keep
the lake till then.”
And the lake therefore remains in her country to this day, while the
great hollow whence it was taken can still be seen in Connaught, bare
and barren, waiting for the waters that never will return.