A smile is nature's best antidote for discouragement. It brings rest to the weary, sunshine to those who are frowning, and hope to those who are hopeless and defeated. A smile is so valuable that it can't be bought, begged, borrowed, or taken away against your will. You have to be willing to give a smile away before it can do anyone else any good. So if someone is too tired or grumpy to flash you a smile, let him have one of yours anyway. Nobody needs a smile as much as the person who has none to give.
Dale CarnegieCriticism of others is futile and if you indulge in it often you should be warned that it can be fatal to your career.
Dale CarnegieLet's find and remedy all our weaknesses before our enemies get a chance to say a word. That is what Charles Darwin did. ...When Darwin completed the manuscript of his immortal book "The Origin Of Species" he realized that the publication of his revolutionary concept of creation would rock the intellectual and religious worlds. So he became his own critic and spent another 15 years checking his data, challenging his reasoning, and criticizing his conclusions.
Dale Carnegie