 is the famous unanswered riddle asked by The Mad Hatter in  "Alice In Wonderland", by Lewis Carroll (qv). Carroll wrote the  riddle as nonsense; it has no answer. This has not stopped people,  despite being repeatedly told that there is not, nor should there  be, any answer, from trying to contrive one. Among the suggestions  are, "because Edgar Allan Poe (qv) wrote on both" and "because the  notes for which they are noted are not noted for being musical  notes" (the second of which is very similar to a solution that  Lewis Carroll (qv) himself wearily suggested when he grew tired of  people asking him about it).