'Then you should say what you mean,' the March Hare went on. 'I do,' Alice hastily replied; 'at least - at least I mean what I say - that's the same thing, you know.' 'Not the same thing a bit!' said the Hatter. 'You might just as well say that "I see what I eat" is the same thing as "I eat what I see"!' 'You might just as well say,' added the March Hare, 'that "I like what I get" is the same thing as "I get what I like"!'
("Alice's Adventures in Wonderland" by Lewis Carroll)
Decir lo que se piensa y pensar lo que se dice no es lo mismo.