“You gave me the key of your heart, my love;
Then why did you make me knock?”
“Oh, that was yesterday, saints above!
And last night I changed the lock!”
–John Boyle O’Reilly (1844-1890) Irish poet, author

“Suddenly she came upon a little three-legged table, all made of solid glass; there was nothing on it but a tiny golden key, and Alice’s first idea was that this might belong to one of the doors of the hall; but alas! either the locks were too large, or the key was too small, but at any rate it would not open any of them.”
–Alice’s Adventures in Wonderland, by Lewis Carroll, 1832-1898

“And running after me, she caught me as I was again trying to force open the door: ‘I won’t allow it; I won’t have my premises spoiled. Go for a locksmith, there’s one about a mile from here. But avast!’ putting her hand in her side pocket, ‘here’s the key that’ll fit, I guess; let’s see.’
And with that she turned it in the lock’ but alas! Queequeg’s supplemental bolt remained unwithdrawn within.”
–Moby Dick or The Whale, by Herman Melville, 1819-1891