Raymond Smullyan. Alice in the country wit (№ 170179)

- But as those who are here in your mind? 'said Alice, who was fed up with all sorts of teachings. - Probably, they are mostly correct ideas, although something may be mistaken?
- In any case! - firmly replied the Duchess. - Behave common people from whence you came. Here those who in his mind are completely accurate in their judgments. All that is true, the common people think is true, everything is false, is false. Alice a little thought.
- I'd like to know - she said - who here is sane and who is mad.