On What Happens on Thursdays, by Lewis Carroll
''He said he would come in,' the White Queen went on, `because he was looking for a hippopotamus. Now, as it happened, there wasn't such a thing in the house, that morning.'
Is there generally?' Alice asked in an astonished tone.
Well, only on Thursdays,' said the Queen."
— Lewis Carroll (Through the Looking-Glass and What Alice Found There)