"Of course not," said the Mock Turtle: "why, if a fish came to me, and told me he was going to a journey, I should say 'With what porpoise?'"
"Don't you mean 'purpose'?" said Alice.
"I mean what I say," the Mock Turtle replied in an offended tone. ...
"I mean what I say" 是一个伪命题，提醒我们在说话时从听者的角度考虑我们所说的话，并对他人的不理解心怀谅解。