Very good and pertinent post if we consider that just yesterday 14 Lewis Carroll's death was commemorated. This is the riddle that the Mad Hatter poses to Alice in Chapter VII of Alice in Wonderland, while drinking tea. Alicia says she knows the answer, but a sudden turn in the conversation prevents her from saying it. Lewis Carroll himself acknowledged in a prologue to the book written in 1896 that when he raised it he had not thought about what the solution might be, but the enigma became so famous that he was forced to offer an explanation, which is the one we all know and which is also an enigma because it is a play on words. I prefer to stay and say what Alice said in the play:

Have you found the solution to the riddle? -asked the Hatter, addressing Alice again.
-No. I give up. What's the solution?
-I have no idea," said the Hatter.
-Neither do I," said the March Hare.
Alice sighed in annoyance.
-I think you could find a better way to kill time," she said, "than to propose riddles without a solution."

Excellent publication, @honeydue. Thanks to you for sharing and to @adsactly for publishing.