If the world should blow itself up, the last audible voice would be that of an expert saying it can't be done.
Peter Ustinov

Finish each day and be done with it. You have done what you could; some blunders and absurdities have crept in; forget them as soon as you can. Tomorrow is a new day; you shall begin it serenely and with too high a spirit to be encumbered with your old nonsense.
Ralph Waldo Emerson

He who has imagination without learning has wings and no feet.
Joseph Joubert