The only real mistake is the one from which we learn nothing.
译文：不装聋作哑、不装傻充愣，就当不了别人的公公、婆婆。
释义：内心纷杂不净，难以领悟真理；意志不坚定，难以成就功业。
The less secure a man is, the more likely he is to have extreme prejudice.